References:

Microchip dsPic 30F Programming reference guide

PIC microcontroller Development Board

(Completed on 2006-10-28)

The ultimate PIC Microcontroller development board. After years of programming PIC microcontroller, I have finally design my super development board to program PIC microcontroller firmware. The automatic programming mode select and the 40 bits LED light bar display have ease my programming process and increase debugging speed by 10 times. I can easily do troubleshooting because of the 40 bits LED display. The LED allows display for 5 bytes of variables using only 3 bits of any output port. I used to allocate PORTD to display one byte of the memory. Debugging used to be slow and tedious. This board also features automatic select to programming mode when the board is powered down. This means that there is no need to do manual switching. The ICSP interface allows the firmware to be loaded to the microcontroller without inserting/removing IC chip.

Features

-Development for 18, 28, 40 pins DIP PIC microcontroller

-Serial Communication RS232, with Tx/Rx transmission activities indicator.

-Changeable microcontroller Crystal Clock

-ICSP programming pins

-Automatic switch to programming mode when board power is turned off.

-Proper labels and easy to view LED bar display, buffered from all the ports. Output pins from all the ports.

-Serial to parallel data latching to extend more output bits from 3 output pins. Output pins with easy to view LED bar display.

-Adjustable dc-dc power supply using LM2576-ADJ IC to cater for 5V and 3.3V power supply system.

-Features 74HC series logic family and Max232 IC for operating on 3.3V power supply. (see logic family selection guide)

-Fuse protection.

Click on the image for Circuit Schematic

For more information for extending microcontroller I/O (input/output) ports using “serial to parrallel” or “parallel to serial” circuit, you can refer to More Circuit Schematic.

The development board uses the following logic IC:

74HC595, serial to parallel with output latched

74HC244, octal logic buffer

MAX232, RS232 to TTL tranceiver

LM2576-adj, DC-DC voltage regulator

For more information on how to select logic family, see “Logic Selection Guide” from Texas Instrument.

Introduction: AUP, CBT-C, CB3T/Q, SSTU, VME, AUC, SSTV, GTLP, Little Logic, AVC, TVC, ALVT, CBTLV, ALVC, CBT, LVC, LV

Mature: AHC/AHCT, LVT-A, ABT, FCT, AC/ACT, HC/HCT, BCT, CD4000

Obsolescence: 74ALS, 74F, 74AS, 74LS, 74S, 74xx (oldest)

(Completed in the year 2005)

My first own build programmer system. Spent quite a lot of time designing and fabricating the plastic box chassis. It works, but I never really work much with it after I brought myself a commercial version.

(Completed in the year 2002-05-xx)

This is a interface board for fitting various model of PIC microcontroller to the programmer. The programming pins numer is different for every PIC microcontroller model. This interface board eliminate the need to build a new programmer board for different PIC microcontroller model.

(Completed in the year 2002-05-xx)

This board is design to be function as a multi purpose PIC microcontroller development board. I have build specially to trial run the microcontroller firmware I wrote. Bi-directional digital buffer are used, to protect the microcontroller from external device during interfacing. After working with microcontroller for some time, I find that this buffer interface is not necessary. Microcontroller I/O ports do not damage easily. When interfacing microcontroller with high powered or unknown devices, opto-coupler can be used instead. Opto-coupler provides maximum isolation as well as protection between the microcontroller and other devices.

Attached to the main PCB is a smaller PCB board. It consist of a MAX232 converting computer RS232 to microcontroller TTL serial signal. This small board also include a charge pump circuit that generate 12V from a 5V source for the purpose of programming the PIC microcontroller. This programmer design “Toolkit TK3 PIC programmer” was taken reference from my favourite hobby magazine “Everyday Practical Electronics“.

Development Board schematic & PCB layout

Programmer Board schematic & PCB layout

(Completed in the year 2002-05-xx)

Input switches and Output LED test board interface. It is very useful when doing microcontroller project, because it can help to indicate if the firmware is running correctly inside the microcontroller. A must have kit when doing digital project.

table updated in 26 May 2007

16
29
39

17
29
40

8
19
27

10

8
19
27

EEPROM
Code Protection
Warning!!!-> very very little memory, 4K only. Not enough for comfortable protocol processing. Please take note.

(Don’t use this in future. Use alternative PIC16F1825)

Compatiable to PIC24F04KA200, with more memory.
Face problem dealing with UART on its revision A0.

(Don’t use this in future. Having problem using the I/O pins as input (RA4, RB4, RA2, RA3), no access to AD1PCFG to enable digital input. Use alternative PIC16F1825)

16
29
39

PIC10F206 Microcontroller Schematic

source code:
2011-11-30 mini RGB microcontroller (c).zip
2011-11-30 mini RGB microcontroller (asm).zip

2009-10-08

Getting my “hello world” firmware loaded into my new hardware design pose the most difficult part of the process. Time consuming doing debugging, and it can takes from half a day to two. The most difficult part, to spent those precious engineering time in debugging. Debugging what I thought I should be good in since I have done so many microcontroller project. Till this day, I still have the problem every time I start microcontroller project after a few months break. The reason I have this guide written. To provide myself possible solution, that can help me, if I encounter the same issue again.

Setting up the environment for project using MPLAB v8.70

1) Create a project folder. Open the MPLAB IDE software.

2) Open a new Project. Project>New… and enter in a name for the project.

3) Select the microcontroller that is use in the project. Configure>Select Device… and select the microcontroller for your project.

4) Check the configuration mode ‘Release’. Project>Build Configuration>Release

5) Select the correct toolsuite for your project. Project>Select Language Toolsuite… for typical C lanaguage implementation, choose “MPLAB” C30 C Complier (pic-30-gcc.exe) v3.24

6) Add in the search path for your microcontroller’s header file. Project>Build Options…>Project>Directories>Include Search Path, choose add to add in the directory that contains the microcontroller’s header files. For my example, the header is located in the directory “C:\Program Files (x86)\Microchip\MPLAB C30\support\dsPIC33F\h”

7) Add in or create all the *.c & *.h files, to start your programming.

I do not have much problem doing the compilation of my C programs. The frustration comes during the loading of my hex codes into my newly design prototype circuit. Most of the time is due to human error, because my prototype board are mainly hand soldered, pin by pin.

On the left is the typical error message I encounter. I am scare of them to be frank. I see them almost every time.

Initializing PICkit 2 version 0.0.3.63
Found PICkit 2 – Operating System Version 2.32.0
Target power not detected – Powering from PICkit 2 ( 3.30V)
PKWarn0003: Unexpected device ID:  Please verify that a PIC24FJ32GA004 is correctly installed in the application.  (Expected ID = 0x44D0000, ID Read = 0x0)
PICkit 2 Ready

As you can see in the error on the right. PICkit is expecting the microcontroller with device ID 0x44D0000. The read by PICkit detects a ID of 0x0. In fact this same error is identical as if the PICkit programmer is not inserted to the ICSP programming pins at all.

This is a hard evident that the microcontroller is not wired properly or evenly not wired at all.

Programming Target (10/8/2009  4:37:06 PM)
PKWarn0003: Unexpected device ID:  Please verify that a PIC24FJ32GA004 is correctly installed in the application.  (Expected ID = 0x44D0000, ID Read = 0x0)
Erasing Target
Programming Program Memory (0x0 – 0x23FF)
   PE Error: Using ICSP
Verifying Program Memory (0x0 – 0x23FF)
   PE Error: Using ICSP
PK2Error0027:  Failed verify (Address = 0x0 – Expected Value 0x40200 – Value Read 0x0)
PICkit 2 Ready

1) The first thing to check if your hardware. It is most of the time the source of the problem. Check if the ICSP programming pins are wired correctly

ICSP pin out

Pin 1: !MCLR

Pin 2: Vdd (3.3V or 5V, depends on the device)

Pin 3: Vss (ground)

Pin 4: PGD (data line)

Pin 5: PGC (clocking line)

Pin 6: unused

Attached on the left is the basic schematic of the microcontroller PIC24FJ32GA004 if your wiring is exactly the same as what is shown, PICkit2 should be able to load the hex file into your controller without any problem.

An advise to you, don’t assume that your wiring is correct. Check 2 or more times to ensure. This is often one of my major mistake make. The schematic is typically correct, but because of the confident doing many similar project, the checking is often the lacking part.

For PIC24FJ series controller, there is a pin Vcap & DISVREG. Make sure that there is the capacitor there. !MCLR pin to be pull up to Vdd using a resistor about 10kohm.

The following pins are to be connected to PIC24FJ32GA004, in order for the ICSP programmer to download the *.hex files onto the microcontroller. Improper connection will definitely generate programming error messages.

Pins connection

Pin 18 connect to !MCLR
Pin 17, 28, 40 connect to Vdd (3.3V)
Pin 6, 16, 29, 39 connect to Vss (Gnd)
Pin 21 connect to PGD
Pin 22 connect to PGC
Pin 7 connect to as Vcap

Front

Back

TQFP-44 Prototype board or adaptor

This sub-board adaptor helps to convert small smd components to 2.54mm pitch for mounting onto pcb. The larger 2.54mm pitch will be easier to work with when doing prototyping. The board is available from PIC-CONTROL part no. PIC-200

http://www.pic-control.com/product/index.htm

2) Check if the header file declare in the source code is correct
#define    __PIC24FJ32GA004__
#include “p24fxxxx.h”

This actually informs the PICkit programmer what type of device it is going to encounter. This is also why the error message indicates the expected ID of 0x44D0000, which is the device ID for PIC24FJ32GA004 microcontroller.

Some example of other device ID for PIC24FJ series microcontroller.

Microcontroller          Device ID

PIC24FJ16GA002     0x00444

PIC24FJ32GA002     0x00445

PIC24FJ48GA002     0x004466

PIC24FJ64GA002     0x00447

PIC24FJ16GA004     0x0044C

PIC24FJ32GA004     0x0044D

PIC24FJ48GA004     0x0044E

PIC24FJ64GA004     0x0044F

You might double check if the microcontroller device is selected correctly under the menu “Configure”. It is probably not necessary as the device select is base on what is written with your source code.

Check out the following notes when designing ICSP on your microchip microcontroller.
Click to enlarge.

Programming Target (10/9/2009  10:30:46 AM)
PIC24FJ32GA004 found (Rev 0x3003)
Erasing Target
Programming Program Memory (0x0 – 0x23FF)
  (Using Programming Executive)
Verifying Program Memory (0x0 – 0x23FF)
  (Using Programming Executive)
Programming Configuration Memory
Verifying Configuration Memory
PICkit 2 Ready

Error encountered while loading codes onto the chip:

“You are trying to change protected boot and secure memory. In order to do this you must select the “Boot, Secure and General Segments” option on the debug tool Secure Segment properties page. Failed to program device”

To program a chip that is code protected, need to set PICkit3 into a special mode.

go to project property>Conf:[default]>PICkit 3>Option categories>Secure Segment>Segments to be Programmed>Boot, Secure and General Segments

Try re-program the chip again. The new code should be able to over-write the old codes on the chip.

Alternative old solution method:
Solution: Goto Programmer > Settings > Secure Segment. Then do a “Earse Flash Device”

#define FIRMWARE_DATED __DATE__

//microcontroller dsPIC33FJ128GP804
#include “p33fxxxx.h”

#define CRYSTAL_MHZ 8
//#define CRYSTAL_MHZ 20

#define XBEE_BAUDRATE _115200bps

#define NUM_OF_LOADCELL 4
#if NUM_OF_LOADCELL == 4
   #define XXX
#elif NUM_OF_LOADCELL == 3
   #define XXX
#elif NUM_OF_LOADCELL == 2
   #define XXX
#elif NUM_OF_LOADCELL == 1
   #define XXX
#else
   #define XXX
#endif

//Features Check
#ifdef __HAS_EEDATA__
   #define XXX
#endif
   #define XXX
#ifdef __HAS_DSP__
   #define XXX
#endif
#ifdef __HAS_5VOLTS__
   #define XXX
#endif
#ifdef __HAS_CODEGUARD__
   #define XXX
#endif
#ifdef __HAS_DSP__
   #define XXX
#endif

#warning Testing only      //print warning message during compile time
#error “No Size 4”      //print error messageduring compile time

//Useful symbols which can be use to load the file name, code line and date of the code compilation
//__FILE__, __LINE__, __DATE__, __TIME__, __FUNCTION__ or __func__

macro definitions (preprocessor #defines)
structure, union, and enumeration declarations
typedef declarations
external function declarations
global variable declarations

For XC8

void __interrupt(high_priority) Interrupt_ISR()

For XC16

void __attribute__((__interrupt__, __shadow__, __auto_psv__)) _DefaultInterrupt(void)

void __attribute__((__interrupt__,auto_psv,__shadow__)) _U1RXInterrupt(void)
void __attribute__((__interrupt__,auto_psv,__shadow__)) _U1TXInterrupt(void)
void __attribute__((__interrupt__,auto_psv,__shadow__)) _U2RXInterrupt(void)
void __attribute__((__interrupt__,auto_psv,__shadow__)) _U2TXInterrupt(void)

void __attribute__((__interrupt__, __shadow__, __auto_psv__)) _IC1Interrupt() //input capture interrupt
void __attribute__((__interrupt__, __shadow__, __auto_psv__)) _IC2Interrupt() //input capture interrupt
void __attribute__((__interrupt__, __shadow__, __auto_psv__)) _CNInterrupt() //input change interrupt
void __attribute__((__interrupt__, __shadow__, __auto_psv__)) _INT0Interrupt() //external interrupt
void __attribute__((__interrupt__, __shadow__, __auto_psv__)) _INT1Interrupt() //external interrupt
void __attribute__((__interrupt__, __shadow__, __auto_psv__)) _INT2Interrupt() //external interrupt
void __attribute__((__interrupt__, __shadow__, __auto_psv__)) _INT3Interrupt() //external interrupt
void __attribute__((__interrupt__, __shadow__, __auto_psv__)) _INT4Interrupt() //external interrupt

void __attribute__((__interrupt__, __shadow__, __auto_psv__)) _T1Interrupt(void) //timer 1 interrupt
void __attribute__((__interrupt__, __shadow__, __auto_psv__)) _T2Interrupt(void) //timer 2 interrupt
void __attribute__((__interrupt__, __shadow__, __auto_psv__)) _T3Interrupt(void) //timer 3 interrupt
void __attribute__((__interrupt__, __shadow__, __auto_psv__)) _T4Interrupt(void) //timer 4 interrupt
void __attribute__((__interrupt__, __shadow__, __auto_psv__)) _T5Interrupt(void) //timer 5 interrupt
void __attribute__((__interrupt__, __shadow__, __auto_psv__)) _T6Interrupt(void) //timer 6 interrupt
void __attribute__((__interrupt__, __shadow__, __auto_psv__)) _T7Interrupt(void) //timer 7 interrupt
void __attribute__((__interrupt__, __shadow__, __auto_psv__)) _T8Interrupt(void) //timer 8 interrupt
void __attribute__((__interrupt__, __shadow__, __auto_psv__)) _T9Interrupt(void) //timer 9 interrupt

void __attribute__((__interrupt__, __shadow__, __auto_psv__)) _SPI1Interrupt(void);

Data type structure. Useful in creating access for data bits, byte or word. This helps saves memory space and data handling codes.

//Settings for individual channel

#define NUMOFCHANNEL 8
#define LED_CH_DATASIZE 8

typedef union
{
unsigned int words[LED_CH_DATASIZE]; //array arranged from low byte to high byte
unsigned char bytes[LED_CH_DATASIZE*2]; //array arranged from low byte to high byte
struct
{
//LSB
unsigned currentlimit:12; //set the absolute Led current rating. If value is 0, it means that current is allowed to shot to the max.
unsigned posEdge:1; //0-positive, 1-negative edge or level trigger
unsigned mode:3; //operating mode
unsigned pulsewidthlimit:16; //max pulse width permitted. (for pulsing mode use)
unsigned retriggerperiod:16; //periodic auto trigger of the pulse. (for pulsing mode use)
unsigned current:12; //current
unsigned stepNum:4; //number of steps before reset
unsigned pulsedelay:16; //the delay before pulse on the LED after a trigger. (for pulsing mode use)
unsigned pulsewidth:16; //pulse width of the pulse. (for pulsing mode use)
unsigned current_null:12; //calibrated current value.
unsigned unused:4; //unused
unsigned unused2:16; //unused
//MSB
};
}LED_CHANNELPROPERTIES;
LED_CHANNELPROPERTIES ledCh[NUMOFCHANNEL];        //creating a variable “ledCh” base on the data type structure LED_CHANNELPROPERTIES.

//Accessing data on the Data structure
ledCh[ch].mode = 0b001;        //accessing the bits (a group of 3 bits) under the variable member “mode”, without affecting the rest of the data in the structure.
ledCh[ch].posEdge = 0b0;        //accessing the bit under the variable member “posEdge”, without affecting the rest of the data in the structure.
ledCh[ch].words[0] = 0x0000;
ledCh[ch].bytes[0] = 0x00;

———————————————————–

//another example of a data type structure

typedef union
{
unsigned int words[NUMOFWORD_PERSTEP_PERCH];        //array arranged from low byte to high byte
unsigned char bytes[NUMOFWORD_PERSTEP_PERCH*2];        //array arranged from low byte to high byte
struct
{
//LSB
unsigned current:12;
unsigned enable:1; //on/off. 0-not in use, 1-in use
unsigned unused:3;
unsigned pulsedelay:16;
unsigned pulsewidth:16;
//MSB
};
}INTRIGGER_CHANNELPROPERTIES;
INTRIGGER_CHANNELPROPERTIES inTrigCh[NUMOFCHANNEL][MAX_NUMOFSTEPS][NUMOFCHANNEL]; //inTrigCh[input trigger channel][step no.][output LED channel]

//accessing the data structure
inTrigCh[inputCh][stepNum][outputCh].enable = 0b1;        //accessing the enable bit, without affecting the rest of the data in the structure.

———————————————————–

typedef union
{
//reset variables for dsPIC33FJ128GP804
unsigned int resetStates;
struct
{
unsigned POR :1; //Power-on Reset Flag bit
unsigned BOR :1; //Brown-out Reset Flag bit
unsigned IDLE :1; //Wake-up From Idle Flag bit
unsigned SLEEP :1; //Wake From Sleep Flag bit
unsigned WDTO :1; //Watchdog Timer Time-out Flag bit
unsigned SWDTEN :1; //Software Enable/Disable of WDT bit
unsigned SWR :1; //Software RESET (Instruction) Flag bit
unsigned EXTR :1; //External Reset (MCLR) Pin bit
unsigned LVDL :4; //Low Voltage Detection Limit bits
unsigned LVDEN :1; //Low Voltage Detect Power Enable bit
unsigned BGST :1; //Bandgap Stable bit
unsigned IOPUWR :1; //Illegal Opcode or Uninitialized W Access Reset Flag bit
unsigned TRAPR :1; //Trap Reset Flag bit
};
}RESET;
volatile RESET reset; //storage for configuration flags status

———————————————————–

typedef union
{
unsigned long reading[4]; //decimal reading value
unsigned char bytes[4][4]; //storage for data

// readingXXX.reading[0] = 0x00000123;
// readingXXX.reading[1] = 0x00004567;
// readingXXX.reading[2] = 0x000089AB;
// readingXXX.reading[3] = 0x0000CDEF;

//print seq 00 00 01 23 00 00 45 67 00 00 89 AB 00 00 CD EF
// uart1TX(readingXXX.bytes[0][3]);
// uart1TX(readingXXX.bytes[0][2]);
// uart1TX(readingXXX.bytes[0][1]);
// uart1TX(readingXXX.bytes[0][0]);
// uart1TX(readingXXX.bytes[1][3]);
// uart1TX(readingXXX.bytes[1][2]);
// uart1TX(readingXXX.bytes[1][1]);
// uart1TX(readingXXX.bytes[1][0]);
// uart1TX(readingXXX.bytes[2][3]);
// uart1TX(readingXXX.bytes[2][2]);
// uart1TX(readingXXX.bytes[2][1]);
// uart1TX(readingXXX.bytes[2][0]);
// uart1TX(readingXXX.bytes[3][3]);
// uart1TX(readingXXX.bytes[3][2]);
// uart1TX(readingXXX.bytes[3][1]);
// uart1TX(readingXXX.bytes[3][0]);

}DATAREADING;
DATAREADING reading;

———————————————————–

//Complex data union, data struct example

typedef enum
{
    CONFIG0=0,
    CONFIG1=1,
    CONFIG2=2,
    CONFIG3=3,
    CONFIG4=4,
    CONFIG5=5,
    MASK=6,
    RUN=7,
    Dianostic=8
}A4963_REGISTER;

typedef struct
{
    unsigned CL:1;
    unsigned CH:1;
    unsigned BL:1;
    unsigned BH:1;
    unsigned AL:1;
    unsigned AH:1;
    unsigned :1;
    unsigned VS:1;
    unsigned :1;
    unsigned LOS:1;
    unsigned OT:1;
    unsigned TW:1;
    unsigned WR:1;
    unsigned REG_ADDR:3;
}REG_DIAGNOSTIC;

typedef union
{
    //array arranged from low byte to high byte
    unsigned int words[9];       
    struct
    {
        //LSB
        struct
        {
            unsigned DT:6;
            unsigned BT:4;
            unsigned RM:2;
            unsigned WR:1;
            unsigned REG_ADDR:3;
        }config0;
        struct
        {
            unsigned VT:5;
            unsigned VDQ:1;
            unsigned VIL:4;
            unsigned IPI:1;
            unsigned PFD:1;
            unsigned WR:1;
            unsigned REG_ADDR:3;
        }config1;
        struct
        {
            unsigned PW:5;
            unsigned DGC:1;
            unsigned SH:2;
            unsigned CP:4;
            unsigned WR:1;
            unsigned REG_ADDR:3;
        }config2;
        struct
        {
            unsigned HT:4;
            unsigned HD:4;
            unsigned CI:4;
            unsigned WR:1;
            unsigned REG_ADDR:3;
        }config3;
        struct
        {
            unsigned SS:4;
            unsigned SD:4;
            unsigned SP:4;
            unsigned WR:1;
            unsigned REG_ADDR:3;
        }config4;
        struct
        {
            unsigned PA:4;
            unsigned SMX:3;
            unsigned SPO:1;
            unsigned SI:4;
            unsigned WR:1;
            unsigned REG_ADDR:3;
        }config5;
        REG_DIAGNOSTIC mask;
        struct
        {
            unsigned RUN:1;
            unsigned DIR:1;
            unsigned BRK:1;
            unsigned RSC:1;
            unsigned DI:5;
            unsigned ESF:1;
            unsigned CM:2;
            unsigned WR:1;
            unsigned REG_ADDR:3;
        }run;
        REG_DIAGNOSTIC diagnostic;
        //MSB
    };
}A4963_DATA;
volatile A4963_DATA a4963_data; //storage for configuration flags status

a4963_data.config0.DT = 0;
a4963_data.config1.VT = 0;
a4963_data.config2.PW = 0;
a4963_data.config3.HT = 0;
a4963_data.config4.SS = 0;
a4963_data.config5.PA = 0;
a4963_data.mask.CL = 0;
a4963_data.run.RUN = 0;
a4963_data.diagnostic.CL = 0;

———————————————————–

Example1 of how to use enum. (see better example2)

Create a header file for Enum “Enum.h”, and place the following enum defintion,

enum BOOLEAN
{
    FALSE=0,
    TRUE=1
};

————————————————————–

For each of the *.c file that you want to use the enum BOOLEAN, include the header file “Enum.h”.

1) declare a enum variable
enum BOOLEAN flag = FALSE;

2) declare a function
enum BOOLEAN isDone()
{
    return(flag);
}

————————————————————–

For header *.h file that you want to use the enum BOOLEAN,

extern enum BOOLEAN;
enum BOOLEAN isDone();

####################################################################################

Example2 of how to use enum. (betterexample)

typedef enum
{
    FALSE=0,
    TRUE=1
}BOOLEAN;

————————————————————–

For each of the *.c file that you want to use the enum BOOLEAN, include the header file “Enum.h”.

1) declare a enum variable
BOOLEAN flag = FALSE;

2) declare a function
BOOLEAN isDone()
{
    return(flag);
}

————————————————————–

For header *.h file that you want to use the enum BOOLEAN,

(have problem here with enum. Prototype declare in the header cannot have the enum as data type.)

enum PORTIN
{
CH1=0,
CH2=1,
CH3=2,
CH4=3,
CH5=4,
CH6=5,
CH7=6,
CH8=7,
IN1=0,
IN2=1,
IN3=2,
IN4=3,
IN5=4,
IN6=5,
IN7=6,
IN8=7
};

enum LED_MODE
{
CONTINUOUS=1,
SWITCH=2,
PULSE=3,
};

enum EDGE
{
POS_EDGE=0,
NEG_EDGE=1
};

//define enum type “EDGE”
typedef enum
{
POS_EDGE=0,
NEG_EDGE=1
}EDGE;

//declare a variable “myEdgeVar” of type EDGE
EDGE myEdgeVar = POS_EDGE;

void initOscillator()
{
// Configure Oscillator to operate the device at 40Mhz
// Fosc= ((Fin/N1)*M)/N2, Fcy=Fosc/2
// N1=4, M=32, N2=2, Crystal = 20MHz
// Fosc= ((20M/4)*32)/2
// Fosc = 80Mhz for 20MHz input clock
// Fcy = Fosc / 2 = 40 MIPS

#ifdef dsPIC33FJ256GP506A
#ifdef FOSC_80MHZ
PLLFBDbits.PLLDIV = 30; // M=32
CLKDIVbits.PLLPRE = 0b00010; // N1=4
#endif
CLKDIVbits.PLLPOST = 0b00; // N2=2
OSCTUNbits.TUN = 0; // Tune FRC oscillator, if FRC is used
RCONbits.SWDTEN=0; // Disable Watch Dog Timer
while(OSCCONbits.LOCK!=1) {}; // Wait for PLL to lock
/*
#elif dsPIC33FJ128GP804
#ifdef FOSC_80MHZ
PLLFBDbits.PLLDIV = 38; // M=40
CLKDIVbits.PLLPRE = 0b00000; // N2=2
#endif
#ifdef FOSC_40MHZ
//Config for 40MHz temporary instead
PLLFBDbits.PLLDIV = 38; // M=40
CLKDIVbits.PLLPRE = 0b00010; // N2=4
#endif

CLKDIVbits.PLLPOST = 0b00; // N1=2
OSCTUNbits.TUN = 0; // Tune FRC oscillator, if FRC is used
RCONbits.SWDTEN=0; // Disable Watch Dog Timer
while(OSCCONbits.LOCK!=1) {}; // Wait for PLL to lock
*/
#endif

//PLL module, Fosc = Fin*(M/(N1*N2))
//= Fin * ((PLLDIV+2)/((PLLPRE+2)*2*(PLLPOST+1)))
//= 8Mhz * ((38+2)/((0+2)*2*(0+1)))
//= 8Mhz * (40/(2*2*1))
//Fosc = 80Mhz

//PLLPRE==2, PLLPOST==0, PLLDIV==78
//= 8Mhz * ((78+2)/((2+2)*2*(0+1)))
//= 8Mhz * (80/(4*2*1))
//Fosc = 80Mhz

//PLLDIV==37
//= 8Mhz * ((37+2)/((0+2)*2*(0+1)))
//= 8Mhz * (39/(2*2*1))
//Fosc = 78Mhz

}

//*************************************************
// IoPinMapping
//*************************************************
//local defination—————–
//define inputPin Function=RPxx pin number
//Input Peripheral pin
#define inputPIN_INT1 RPINR0bits.INT1R
#define inputPIN_INT2 RPINR1bits.INT2R
#define inputPIN_T2CK RPINR3bits.T2CKR
#define inputPIN_T3CK RPINR3bits.T3CKR
#define inputPIN_T4CK RPINR4bits.T4CKR
#define inputPIN_T5CK RPINR4bits.T5CKR
#define inputPIN_IC1 RPINR7bits.IC1R
#define inputPIN_IC2 RPINR7bits.IC2R
#define inputPIN_IC3 RPINR8bits.IC3R
#define inputPIN_IC4 RPINR8bits.IC4R
#define inputPIN_IC5 RPINR9bits.IC5R
#define inputPIN_IC7 RPINR10bits.IC7R
#define inputPIN_IC8 RPINR10bits.IC8R
#define inputPIN_OCFA RPINR11bits.OCFAR
#define inputPIN_OCFB RPINR11bits.OCFBR
#define inputPIN_U1RX RPINR18bits.U1RXR
#define inputPIN_U1CTS RPINR18bits.U1CTSR
#define inputPIN_U2RX RPINR19bits.U2RXR
#define inputPIN_U2CTS RPINR19bits.U2CTSR
#define inputPIN_SDI1 RPINR20bits.SDI1R
#define inputPIN_SCK1IN RPINR20bits.SCK1R
#define inputPIN_SS1IN RPINR21bits.SS1R
#define inputPIN_SDI2 RPINR22bits.SDI2R
#define inputPIN_SCK2IN RPINR22bits.SCK2R
#define inputPIN_SS2IN RPINR23bits.SS2R

//define RPxx pin number=outputPin Function
//RP pins
#define RP00 RPOR0bits.RP0R
#define RP01 RPOR0bits.RP1R
#define RP02 RPOR1bits.RP2R
#define RP03 RPOR1bits.RP3R
#define RP04 RPOR2bits.RP4R
#define RP05 RPOR2bits.RP5R
#define RP06 RPOR3bits.RP6R
#define RP07 RPOR3bits.RP7R
#define RP08 RPOR4bits.RP8R
#define RP09 RPOR4bits.RP9R
#define RP10 RPOR5bits.RP10R
#define RP11 RPOR5bits.RP11R
#define RP12 RPOR6bits.RP12R
#define RP13 RPOR6bits.RP13R
#define RP14 RPOR7bits.RP14R
#define RP15 RPOR7bits.RP15R
#define RP16 RPOR8bits.RP16R
#define RP17 RPOR8bits.RP17R
#define RP18 RPOR9bits.RP18R
#define RP19 RPOR9bits.RP19R
#define RP20 RPOR10bits.RP20R
#define RP21 RPOR10bits.RP21R
#define RP22 RPOR11bits.RP22R
#define RP23 RPOR11bits.RP23R
#define RP24 RPOR12bits.RP24R
#define RP25 RPOR12bits.RP25R

//Output Peripheral pin
#define outputPin_NULL 0
#define outputPin_C1OUT 1
#define outputPin_C2OUT 2
#define outputPin_U1TX 3
#define outputPin_U1RTS 4
#define outputPin_U2TX 5
#define outputPin_U2RTS 6
#define outputPin_SDO1 7
#define outputPin_SCK1OUT 8
#define outputPin_SS1OUT 9
#define outputPin_SDO2 10
#define outputPin_SCK2OUT 11
#define outputPin_SS2OUT 12
#define outputPin_OC1 18
#define outputPin_OC2 19
#define outputPin_OC3 20
#define outputPin_OC4 21
#define outputPin_OC5 22

/*
void ioPinMapping()
{
//__builtin_write_OSCCONL(OSCCON & 0xbf);
// Unlock Registers – MUST be in asm due to strict timing reqs
asm volatile( “MOV #OSCCON, w1 \n”
“MOV #0x46, w2 \n”
“MOV #0x57, w3 \n”
“MOV.b w2, [w1] \n”
“MOV.b w3, [w1] \n”
“BCLR OSCCON, #6 “);

#ifdef ETHERNET_COMMUNICATION
//map UART1 pins
inputPIN_U1RX=16; //link input U1RX =Pin no.
RP02=outputPin_U1TX; //link output Pin RP17= U1TX
AD1PCFGLbits.PCFG6=1; //ADC config, disable ADC on the pin for input. Input will be digital input instead of the default analog. Output is digital by default, therefore no ADc config on RX pin
AD1PCFGLbits.PCFG4=1; //ADC config, disable ADC on the pin for input. Input will be digital input instead of the default analog. Output is digital by default, therefore no ADc config on TX pin
#endif
#ifdef RS232_COMMUNICATION
//map UART1 pins
inputPIN_U1RX=18; //link input U1RX =Pin no.
RP17=outputPin_U1TX; //link output Pin RP17= U1TX
AD1PCFGLbits.PCFG8=1; //ADC config, disable ADC on the pin for input. Input will be digital input instead of the default analog. Output is digital by default, therefore no ADc config on RX pin
AD1PCFGLbits.PCFG7=1; //ADC config, disable ADC on the pin for input. Input will be digital input instead of the default analog. Output is digital by default, therefore no ADc config on TX pin
#endif

//map UART2 pins
// inputPIN_U2RX=18; //link input U1RX =Pin no.
// RP17=outputPin_U2TX; //link output Pin RP17= U1TX
// AD1PCFGLbits.PCFG8=1; //ADC config, disable ADC on the pin for input. Input will be digital input instead of the default analog. Output is digital by default, therefore no ADc config on RX pin
// AD1PCFGLbits.PCFG7=1; //ADC config, disable ADC on the pin for input. Input will be digital input instead of the default analog. Output is digital by default, therefore no ADc config on TX pin

//map SPI1 pins
inputPIN_SDI1=9; //link input SPI1 data IN =Pin no.
RP22=outputPin_SDO1; //link output Pin = SPI1 data OUT
RP08=outputPin_SCK1OUT; //link output Pin = SPI1 clock output
//RP08=outputPin_SS1OUT; //link output Pin = SPI1 slave select output

//config for input capture
inputPIN_INT1=1; //use input capture as an input1
inputPIN_INT2=21; //use input capture as an input2
inputPIN_IC1=19; //use input capture as an input3
inputPIN_IC2=20; //use input capture as an input4  

//__builtin_write_OSCCONL(OSCCON | 0x40);
// Lock Registers – MUST be in asm due to strict timing reqs
asm volatile( “MOV #OSCCON, w1 \n”
“MOV #0x46, w2 \n”
“MOV #0x57, w3 \n”
“MOV.b w2, [w1] \n”
“MOV.b w3, [w1] \n”
“BCLR OSCCON, #6 “);
}
*/

First, the I/O pins are tied to the PORT registers, as you’d probably guess. However, on reset, all port pins are set to inputs. If you want to use a port pin as an output, you’ll need to change the corresponding direction bit from a 1 (the default) to a 0. So to prepare PORTB pin 0 for output you might write:

	bsf status,rp0  ; rp0=1 - select bank 1
        bcf trisb,0     ; port b direction bit 0 = 0
        bcf status,rp0  ; rp0=0 - select bank 0

It is good practice to reset the bank to 0 as soon as you are done accessing another bank. So then if you wanted to set the output to 1 you might write:

        bsf portb,0  

The other quirky behavior is the interaction between INDF and FSR. INDF isn’t like an ordinary register. Instead, it mirrors another register indicated by the address in FSR. For example, location 0x6 is the PORTB register. Suppose you write:

        movlw 6     ; W=6
        movwf fsr   ; FSR=W

Now the INDF register is really an alias for PORTB. So you might write:

        bsf indf,0  ; set bit 0

 This instruction doesn’t really set bit 0 of INDF, it sets bit 0 of PORTB. Since FSR is an 8-bit register, it can contain a complete address from bank 0 or bank 1 (just treat bank 1 addresses as ranging from 0x80-0xFF). To access bank 3 and and bank 4 using FSR/INDF, you have to set the IRP bit in the STATUS register. RP0 and RP1 don’t apply to INDF access!

Op Amps for Everyone, by Bruce Carter and Ron Mancini from Texas Instruments.

op amps for everyone (Texas Instrument).pdf

op amps for everyone third edition 2009 (Texas Instrument).pdf

Op-amp application notes from National Semiconductor,

An applications guide for op-amps.pdf

Single rail op-amp design from Texas Instruments

single power supply design.pdf

Various precision op-amp rectifier design.

http://sound.westhost.com/appnotes/an001.htm

Type of Op-amp circuit

1) Non-Inverting amplifier
2) Inverting amplifier
3) Unity Buffer amplifier (Voltage follower)
4) Differetial amplifier
5) Suming amplifier
6) Instrumentation ampilfier
7) Oscillator
8) Comparator
9) Threshold detector
10) Zero Level detector
11) Schmitt trigger
12) Integration
13) Differentiation
14) Rectifier
15) Logarithmic output
16) Exponential output

1) Non-Inverting amplifier Vout = (1+ R2/R1) Vin – high input impedance – low output impedance – higher bandwidth – minimum gain of 1
A resistor R1||R2 = (R1 x R2) / (R1 + R2) is inserted just before the +ve terminal will keep the input current better balanced.
The added voltage divider has introduced a voltage offset to the output signal Vout.
2) Inverting amplifier Vout = -(Rf/Rin) Vin – gain can be less than 1   When analysing the op-amp as an amplifier (ideal op-amp), the +ve and -ve is to be having the same voltage potential.
A resistor Rin||Rf = (Rin x Rf) / (Rin + Rf) is inserted just before the +ve terminal will keep the input current better balanced.
The added voltage divider has introduced a voltage offset to the output signal Vout.
The voltage divider provides a voltage level which the amplification will be based from. Signal with the same voltage level will not be shift in position, while the rest of the voltage level will be amplified.
3) Unity Buffer amplifier (Voltage follower) Vout = Vin – high input impedance – low output impedance
4) Differetial amplifier. – Poor input impedance
Voltage follower added in the front of the input to improve the input impedance. This is also similar to an instrumental op-amp.
Instrumentation amplifier.

Op-amp Selection

(cheap precision op-amp)

Precision usually means a low input offset voltage, which is quite important for voltage comparator, or amplifying small differential input signal.
Input offset <0.5mV will be consider as precision op-amp.
Input offset guide from Analog Device “MT-037, Tutorial Op-amp Input offset voltage.pdf”

Capacitor for Signal Filtering

The following article is a simplied understanding of signal filtering. Basic knowledge of signal filtering is still required before reading this section.

The simplest signal low pass filter (LPF) is presented on the right consist of a resistor and capacitor. It is commonly known as RC filter.

This RC layout is applied to circuit with low impedance input, high impedance output. The resistor will be required to complete the filter function. Signal oscillation may occured is the resistor is omitted.

One example would be LPF filtering at the output of the op-amp amplifier circuitry, where filtering is applied to the varying input signal/voltage.

The cutoff frequency of this RC filter
fc = 1/(2πRC)

R will need to be significantly small compare to the load. If the load impedence is high (infinity), then the value of R becomes not very important. If the load impedence is finite, R should be smaller than 1/10 of the load.

Click here for the calculator for the LC filter. frequency and time domain results are on the fly.
– http://sim.okawa-denshi.jp/en/CRtool.php (generate freq/time domain graph on the fly)
– http://www.2pif.com/high-low-pass-filter.php (simple calculator)

RC filter, the simplest low pass filter.

Another way of looking at the same RC filter.

Ideal analysis of the circuit
The signal in the DC or lower frequency signal can be fully transfered to the high impedence (open circuit) output, while the high frequency signal will be absorbed on the resistor (R) components.

What the high frequency signal will see:
AC signal see resistor as a load, capacitor as a short circuit, while inductor as an open circuit. High frequency signal is able to see the capacitor (C) component as a short circuit. The voltage potential of Vout is seen to be the same as the ground reference. This means that the AC signal will be completely absorbed by the resistor R component. High frequency component will not be available at Vout. They are filtered by the RC filter.

What the low frequency signal will see:
DC signal see resistor as a load, capacitor as an open circuit, while inductor as a short circuit. Low frequency signal is unable to see the capacitor (C) component well. The point Vout is seen to have a very high impedance load. This means that the DC signal will be completely transfer to the open circuit output load at Vout. The R component will be seen as small as compare to the open circuit output load. Using the voltage divider concept, most of the low frequency signal will fall on the output Vout. The low frequency signal managed to pass through the RC filter.

Please note that the above explaination is a simplfied analysis of a filter. Ideal analysis helps us to understand the circuit topology (function) at a glance without the need for detail computation. In reality, the open/short circuit represent the degree of attenuation faced by the signal. The degree of signal attenuation is dependant on the frequency of the signal and the capacitor’s capacitance.

This is another low pass filter consist of only a capacitor. This type of filter will work for current source input. Vin = Vout.

One example would be the capacitors that are found on typical dc power supply filtering at its input or output. Decoupling capacitors (100nF) that are normally found near the power input of an IC is also another example.

Capacitances required to attenuate or suppress signal of certain frequency. Please note that this formula and the table presented on the right is an approximation for filtering noise from a DC signal.

Xc = 1 / (2π f C)

C = 1 / (2π f Xc )

where Xc is the reactance of the capacitor. Xc of 1.0 for the capacitor (open circuit) is possible with lower fequency signal or lower capacitance. To attenuate the AC signal of a particular frequency, Xc has to be low with the correct capacitance implemented.

Example:

To attenuate a 50Hz signal by 10 times.

C = 1 / (2π x 50Hz x 1/10) = 31,830uF

This means that to attenuate the 50Hz component by 10 times requires about 33,000uF capacitor connected from the signal to the ground line. This capacitor will filter any frequncy >50Hz on the line.

The table on the right is a simplified guide, which recommend the capacitance to use as a low pass filter for attenuating a particular frequency.

Max frequency for capacitor (taken from “Op Amps for Everyone”)

Active filter with op-amp

For flat frequency response, use Butterworth filter

For a sharp cutoff frequency, use Chebyshev filter

For linear phase, use Bessel filter.

I didn’t realised that transistor switching speed can be so important until I had encountered a problem using it for SPI communication. The data communication gets corrupted. Go through all the codes, and eventually found that the transistor switching speed was slow. The current batch of transistor is different from my previous batch; and I always thought that all BC817 npn transistor is the same. I am wrong, it is not. The problem might have been due to my design as well, unable to discharge the base signal in time, to turn off the transistor.

Ch1(yellow) shows the signal input through a 1kohm resistor to the base of the npn transistor. Ch2(blue) is the output at the transitor’s collector terminal, with a pull up resistor of 560ohm. The is

The following present the various BC817 transistor’s switching digital speed.

Switching speed of my original transistor.

delay of about 0.7us.

using npn BC846

delay of about 2us.

using npn BC817

delay of about 2.5us.

BC817-16LT1G

delay 2us

MMBT4401LT1G

delay 4.5us

MMBTA05LT1G

delay 0.25us

Effect of the signal switching without a 10kΩ resistor across the Vbe terminal of a npn transistor BC817.

There is a slight improvement in delay, but not very noticable.

Effect of the signal switching without a 10kΩ resistor across the Vbe terminal of a npn transistor BC817.

More than 100% improvement shortening the delay, of the inverted signal by about 1us.

PCB is the abbreviation for Printed Circuit Board. Some may refer it as PWB which stands for Printed Wiring Board. The board consist of copper tracks connection printed on the surface of a non-conducting material. Your designed circuit connection will be contained within this board. This method of fabrication is an efficient method for reproducing a circuit. The circuit quality can be more consistent and the reproduction can be faster. This makes it suitable for manufacturing large quantities of electronic circuits.

Are you thinking of building your own PCB board at home? Do you have an electronics project in mind? Then you have come to the right site. This is a step-by-step guide to building your own PCB boards, complete with photos and video illustrations.

Home DIY PCB board finished product

1. PCB board design
2. Printing Artwork
3. Exposure
4. Developing
5. Etching
6. Cuting and Drilling
7. Tinning and Masking
8. Other method of PCB making

The following project will introduce you to the basic steps in fabricating a circuit board at home. For low quantity fabrication, this method can save you some time and help you stay within your budget.

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For a simple prototype circuits, I would recommend point-to-point wire solder. While this process is tedious and takes time, your project cycle will be shorter than making a PCB which is more or less permanent. Individual wire connection are soldered directly onto the component leads or pins. The wiring makes modification quick and easy.

This photo is an example of a point-to-point wire wrap circuit. The leads are soldered into place. The colored wiring helps keep things organized, but the back side of the project still looks like “spaghetti”. Constructing a board in this manner requires proper planning of your component positioning for minimum wiring work. You may be constantly flipping the board over from front to back to double-check the connections. It can be quite fast if you are used to visionlizing the components from the back side.

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Come, join in, as we walk through the process of PCB fabrication. We will proceed step-by-step. It’s as easy as ABC and you will soon be the proud owner of your own custom printed circuit board.

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At this time, you might be aware of an alternative. It is possible to have your designs produced by professional companies that specialize in PCB board fabrication.

Professional PCB board fabrication

PCB fabricating machine is more efficiency for mass production. For professional looking PCB board, you may outsource the task to a PCB design house or manufacturer. Well established PCB manufacturer normally ask for higher fabrication volume. There are manufacturer that can do PCB fabrication in lower volume for your prototype. Some accept a few pieces, and even provide you with software for drawing your PCB design. Lead-time is typically a week or 2, while some manufacturer may offer express PCB fabrication service. If you are looking into high volume professional PCB board, China can offer a more competitive price. More reference to these manufacturer and PCB fabricating machines is available on this website.

Various professional PCB manufacturer.

San Francisco Circuits

“prototype pcb – The PCBs from Seeed Studio Fusion is short delivery time, competitive price and high quality.”

In order to have your PCB boards professionally fabricated, the factory will need your design in a format called a “gerber” file. These gerber files are a list of mechanical instructions for fabricating the PCB. See the DIY steps in the section that follows to learn how to generate your own gerber files. The factory will usually charge a setup fee for each fabrication job. The cost per piece is usually low.

Most of the time you may only have the circuit designed on a piece of paper. You can also engage a professional to draft and generate the manufacturing gerber files. Be sure that your circuit is a working design and you have the connection drawn correctly before submitting to them for drafting. I don’t think they verify your design. You also need to prepare the component datasheets or sample, so that they can draw out the component’s soldering pad or footprint that your circuit is using. If the footprint is wrong, you will not be able to solder your component onto the board probably. Any requirement, example- the placement of the component, you should also indicate them clearly.

The design should also indicate the type of connector you want to use. I usually forgot to draw out the connector component. You can seek for their recommendation on those connector or other components that may not be critical to your design.

The computer drafted schematic and pcb layout will be sent for your final verification. Once you acknowledge the design, they will then generate the gerber files for your pcb fabrication submission.

Various Schematic Capture & PCB Layout Vendor

            http://www.shinmark.com

Of course, if you do not have the complete circuit designed, you will have to engage a circuit designer to design a circuit for you. Designing services can be quite expensive.

If you want to fabricate the professional looking green board for a smaller quantity, you can try PIC-CONTROL. The gerber files are submitted to them for pcb fabrication at a reasonable price. However the delivery lead time is slower. About 2 times longer as compare to the typical manufacturer who can deliver the fabricated board in 1-2 weeks times.

They also do electronic circuit design, custom made controller kit, drafting, programming, engineering and reverse engineering stuff, mainly in the area of electronics.

A computer aided design for the schematic capture and pcb gerber file is usually a major cost. I usually DIY, drafting out the design on my own. It save me quite a lot by generating my own gerber files. I can understand why the charge for the design drafting is usually high. There is quite a lot of work in drafting out the design file. It is a time consuming task.

1.   PCB board design

Material and Equipment

• electronics schematic design

• computer

• Protel DXP or PCB design software

software for

drawing PCB board.

Protel DXP software enviroment.

component layout & traces diagram.

new Protel DXP version (2005).

1.1 PCB design introduction

Before any PCB fabrication can be done, we need to design PCB electrical pads for component placing and trace for component connectivity. It can be draw by hand but if your design is very complex, the PCB software will be very helpful. The software have ready to use components footprint, and modification can be easy done, saving you a lot of time and effort as compare to manual drawing.

There are various brand of software for designing and drawing PCB, and most of them can generate gerber file (*.gbr) which is a common file format used for PCB fabrication in the local industries.

Professional PCB software such as CADSTAR and PROTEL can easy cost above thousand of dollars. Simple and basic PCB software such as Eagle or Easy-PC is slightly lower in cost, in the range of about $500 to $1200. They are cheaper in cost, but features can be limited. Limitation can be in the form of limited board size, number of board layer or the number of component’s pin allowed in the design. Professional PCB software has a lot more sophisticated features to make the PCB design process more efficient. Software trials are available from most of these PCB vendors, for user to evaluate.

Various electronics schematic & PCB design tools.

Easy-PC from Number One Systems

CADSTAR from Zuken	Eagle from Cadsoft

Alternative you can engage professional help for the PCB design work, to relieve yourself from the extensive software training. With the experience and expertise from a PCB design specialist like Quantum CAD, you can be sure that your project can be in time and well taken care of. Demanding layout design for analog or any high frequency circuitry, would seems like a breeze in your development work.

In this fabrication trial, Protel DXP is used to aid schematic design and PCB layout. It is quite user friendly and technical support is strong in terms of user group and tutorial documentation.

Gerber file is not used in this home fabrication, instead a pictorial format save in *.pdf file. *.gbr gerber file is normally use in local fabrication house. The component layout and traces generated are save onto the *.pdf file.

The PCB artwork is now in *.pdf format and is ready for printing.

For more information on Protel DXP, you may refer to the following website, http://www.altium.com/

A good electronics design is not stop at the schematics. You may have a very good circuit schematic but it can still create problems for you if the components & traces are not place properly. This is especially important for analog circuits. Understand how to place components and route the power/signal pcb trace is also very important. Understanding radio frequency and high frequency theory will help a lot. I have a delicate page specially for PCB trace.

I have also started a website to document some common surface mount component footprint for references.

More PCB footprint references here. Footprint

Here is a reference on PCB design guideline that I got it from a website. Quite a useful information to guide you into design a proper PCB board.

Board Design Guidelines 2003 Rev-A.pdf

Also another good reference from Texas Instruments about PCB layout recommendation is available in the section Analog Electronics.

op amps for everyone (Texas Instrument).pdf

The following are some of the advance topics that you may like to research further into, if you are interested to find out more about PCB design. http://www.ipc.org

– IPC Designer and Advanced Designer Certification,

– IPC-T-50 Terms and Definitions for Interconnecting
and Packing Electronics Circuits,

– IPC 2222, Sectional Design Standard for Rigid Organic
Printed Boards

– IPC 2221, Generic Standard on Printed Board Design

– IPC-D-325 A, Documentation Requirements for Printed
Boards, Assemblies and Support Drawings

Layout

– Characteristics of Grid Systems

– Purpose of Tooling Holes

– Feature Formed in Copper

– Through-Hole Land & Tolerance Requirements

– Design Differences for SMT vs. Through-Hole

– Interrelated Considerations for Design

– Printed Boards & Assemblies Viewing Principles

Electrical considerations

– Schematics/Logic Transformation for Component Arrangement

– Schematic and Logic Symbols

– Functional Electrical Characteristics

Materials

– Copper Clad Laminates

Component requirements

– DIP & SIP Components

– Clinched & Unclinched Leads

– Point-to-Point Wires

– Axial & Radial Lead Mounting Differences

– DIP & Chip Carrier Sockets

– Edge-Board Connectors

– Characteristics of a bus bar

– Jumper Wires

– Purpose of Stiffeners

– Purpose of eyelets

– Differences between Automatic & Manual Placement

– Non-standard Parts Information

Assembly requirements

– Differences Between Manual & Pick-and-Place SMT Placement

– Considerations for Component Mounting

– Legend & Polarity Markings

Board fabrication

– Board & Assembly Panelization

– Hole Types & their tolerances

– Coating & Markings Used on Printed Boards

Physical board characteristics

– Thermal Management for Assemblies

– Thermal Management for Boards

Documentation

– Tolerancing Methods

– Datum Features & Location Principles

– True Positioning Dimension Techniques

– Conductive Pattern Location to Datum References

– Plated-Through-Hole Dimensions & Grid Location

– Tooling Hole Location Documentation

– Datum Symbols and Hole Description

– Documenting Fastening Hardware

– Minimum Drawing Requirements

– Master Drawing Hole & Conductor Description

– Minimum Requirements for Master Drawing

– Artwork Acceptance Criteria Inspection and test

– Testing & Techniques & Procedures

Reliability

– Reliability Terms & Design Issues

High Speed Design

RF Design

Design for EMC

Singapore Customized, custom made Electronics Circuits & Kits

2.   Printing Artwork

Material and Equipment

• PCB artwork

• paper

• printer

• transparency

• laser printer or photo copier

material for the making of the transparency film.

a closer view of a printed PCB pad and traces photocopied onto a transparency.

2.1 Artwork introduction

The PCB layout can be printed from a normal home printer onto a white piece of paper. The printing will be photocopied to a transparency. The transparency will be use for photo-resist PCB board exposure in the next stage.

A laser printer is prefer for sharper trace, especially if the traces are very close to each other. The laser printer can also print directly to transparency.

The transparency is cut to PCB size 15x10cm. Five PCB artwork are squeeze and arranged to maximize board usage.

There is also another popular DIY call the tone transfer method. Basically, it is using a laser printer to print your art work on a piece of paper. The toner print out is then iron onto a piece of copper plated board. This forms the etch resist layer on top of the board which can be send to the etching process.

The following link provide further information on this method. http://www.fullnet.com/~tomg/gooteepc.htm

The advantage of tone transfer is that it is simple, fast and does not require special positive acting presensitized (photo sensitive) PCB board.

The following step presents the traditional photo exposure method. The etch resistance layer can be formed on the photo sensitive board after the exposure.

3.   Exposure

Material and Equipment

• ultra violet lamp

• a box

• Positive Acting Presensitized PCB board

• transparency with PCB artwork printed

• scotch tape

ultra-violet lamp (left) to expose the photo-resist coated Kinsten PCB board (right).

3.1 Exposure introduction

A typical Ultra Violet UV lamp for exposure on a Positive Acting Presensitized Kinsten PCB board.

   Where to buy them locally???

The ultra violet UV lamp is available in most lightings shop. I brought it at a electrical shop along kelantan lane (near Sim Lim Tower). The Kinsten PCB board, I brought in from Bell System, #03-12, Sim Lim Tower. It is also available in another shop Sunlight.

peeling off the protective film from the PCB board.

3.2 Preparing PCB board for exposure

Tear off the white/black protective film on the photo-resist board. Place the transparency artwork on top of the PCB board. Secure the artwork position with scotch tape.

laying film on PCB.avi (3.2MB)

Alternative you can buy a bare copper board and spray on the photo resist chemical which will be similar to the ready product photo-resist board that I have brought.

3.3 Exposure setup

If you have a piece of glass, place it on top, to make a good contact between the artwork and the PCB board. Close proximity should be maintain to make sure that trace are not expose to the UV light. I actually make this box out of a shoes box to prevent over UV exposure to the PCB board.

PCB setup in the exposure box.avi (1.5MB)

ultra-violet exposure

3.4 PCB exposure

Turn on and expose the PCB board for 90 seconds for ultra violet lamp, or 6-10 minutes for normal fluorescent lamp.

The above reference is base on the guideline of the lamp of about 5cm distance away from the artwork PCB. If the distance is far from the typical one, the exposure time should increase proportionally.

exposure to ultra violet light.avi (0.9MB)

There following introduce you to the various PCB substrate that you might consider before fabricating your PCB board. For typical applications, FR2 or FR4 board will be more than sufficient for your project. For delicated projects, you may consider the reference for the type of PCB material suitable for your appliation.

Various type of PCB materials

CEM-1 (Composite Epoxy Material):

CEM-1 specification

FR-1 Paper/phenolic (Flame Resistance-1): Room temperature punchable, poor moisture resistance

FR-1 specification

FR-2 Paper/phenolic (Flame Resistance-2): low cost pcb material usually found in high volume consumer products. Suitable for single sided PCB consumer equipment, good moisture resistance.

94VO material

FR-3 Paper/epoxy (Flame Resistance-3): Good of mechanical and electrical properties.

FR-4 Fibreglass (Flame Resistance-4, Glass cloth/epoxy): Excellent mechanical and electrical properties. Fibreglass pcb material offers a strong substrate than FR-2. The specification for a typical FR-4 board would be of thinkness 1.6mm, 1oz copper track, green solder mask, white silkscreen, double sided, etc…

FR-4 specification

tg135-tg170 material

FR-5 Fibreglass (Flame Resistance-5, Glass cloth/epoxy): High strength at elevated temperatures, self-extinguishing.

G10 Fibreglass (Glass cloth/epoxy): High insulation resistance, highest bond strength of glass laminates, high humidity resistance.

G11 Fibreglass (Glass cloth/epoxy): High flexural strength retention at high temperatures, extreme resistance to solvents.

Flexible PCB: thin and flexible pcb, typically design with movable component.

Ceramic/Metal/Aluminium substrates/base: provides better heat dissipation. Often used component that dissipate a lot of heat. Example: high power LED component, power transistors, etc…

Radio Frequency, Rogers PCB: low dielectric plastics suitable for high frequency applications.

Other PCB laminate materials name,
– CEM-3
– CEM-5
– BT-Epoxy
– Cyanate Ester
– Polyimide
– PTFE, Polytetrafluoroethylene (Teflon)

References:

http://www.trianglecircuits.com/substrates.html

4.   Developing

Material and Equipment

• Sodium Hydroxide or Developer solution

• distill or plain water

• gloove

• glass, plastic, wooden rod or old chopstick

• container slightly bigger than the PCB board

• exposed PCB board

• container with water for washing

Sodium Hydroxide NaOH, and a pair of Gloves.

4.1 Developer introduction

Sodium Hydroxide is used as a developer. Correct proportion is necessary as too much will destroy the photo-resist coating instantly, while too little will have no effect in developing the PCB.

Commercial developer solution (pre-mixed with distill water) might work better since mixture is in the correct ratio for PCB developing.

Silicate Based Product make a better developer as less likely to be over-developed. Higher concentration will increase the developing speed.

I have seen on other website that the chemical NaOH is used as the drain pipe cleaner.

   Where to buy them locally???

You can buy alternately pcb developing solution from Bell System, #03-12, Sim Lim Tower. Or visit the local chemical store in Singapore

 Visit Dickson Chemicals,

the local chemical store in Singapore

Dickson Chemicals

www.dicksonchemical.com.sg

Tel: 6280 0468

Fax: 6281 1082

30 Shaw Road #05-05,

Singapore 367957

mixing solution, NaOH chemical with water.

4.2 Developer mixture

I have used a old ice-cream container to mix the solvent. The solvent composite for making the developer consist ratio of about

1unit of Sodium Hydroxide is to

20 unit of Water.

The solution must be of uniform concentration. Stir the mixture until NaOH is fully dissolved in the water. If the chemical is not fully dissolved, the region with concentrated NaOH can destroy the photo-resist coating instantly.

Use a glass rod when working with chemical if possible. Glass material is less reactive with most chemical.

mixing NaOH developer solution.avi (3.4MB)

When mixing NaOH to water, heat will be produce. Stir the water solution constantly while adding in NaOH slowly.

PCB developing. washing away photo-resist coating that are expose to the ultra-violet in the earlier stage.

4.3 Developing PCB board

Developing PCB board by dipping into the chemical solution. For this setup, I am also using ice-container.

During the developing process, the chemical board should be agitate constantly until the board is developed.

developing PCB board.avi (3.6MB)

The board is fully developed when the PCB traces appear green in color. This green layer is the photo resist layer which protect the copper surface underneath during the etching process. The region to be etched away later will be expose and is brown in color. The brown color is the actual color of the copper. There is no photo-resist coating to protect the surface.

Rinse the developed PCB board with running water after developing.

picture of a developed PCB board.

4.4 Over and under developed board

The left portion of the board is developed fairly. Notice that there are still some unwanted fade green coating on the copper surface. The board has been soaking in the developer solution for quite some time but the green photo-resist coating is still not remove. This is probably due to inadequate UV exposure time. The UV exposure for this board is exactly 60 seconds. The UV exposure should be 90 seconds instead. It is better to over exposed during the UV lighting process.

There is no attempt to dip the board for a longer period or using stronger solution to remove the fade green coating. It may just cause the dark green pattern to be washed away as well.

The photo-resist layer on the right portion of the board is being washed away. The board is dipped into the solution, without dissolving the NaOH chemical completely. The strong concentration of the chemical have wash away the coating instantly. This example serve as a reminder to stir and dissolve the mixture well before any attempt to develop the PCB board.

mending the circuit trace that are over developed.

This is the marker use in the demonstration. A fine tip oil base black marker from “ZEBRA NAME PEN” made in Japan.

4.5 Repairing over developed board

Sometimes, thin traces on the board may be over-developed. The required trace is not protected by the photo-resist coating after soaking for too long in the developer. The trace has to be protected or it will be etch away in the etching process. These broken or missing circuit trace pattern can be corrected and repaired by drawing over the copper surface with a Etch resist marker. The marker ink will cover up the copper region and acts as etch resistance during the etching process.

There are commercial etch resist marker available, however a general purpose oil base marker will be just as good for use as a etch resist coating. It is a commonly available permanent marker, meant for general use.

   Where to buy them locally???

I am fortunate to test out my zebra name pen marker can actually work as an etch resist shield. You can easy get this type of marker in our local stationary shop. For example, Popular Book shop. If you are looking for a professional etch resist marker, you can buy them from Farnell. They should have it. The tray is actually also a old ice-cream box.

 Visit Dickson Chemicals,

the local chemical store in Singapore

Dickson Chemicals

www.dicksonchemical.com.sg

Tel: 6280 0468

Fax: 6281 1082

30 Shaw Road #05-05,

Singapore 367957

over developed PCB board, with all traces wiped away. The NaOH mixture is too strong. The photo-resist layer got wipe out instantly.

4.6 Over developed board

The photos show the results of a over developed board. Too much chemical was mix in the solution, resulting in a very strong developer solution. The green photo-resist coating on the board was wiped away instantly. The clear and sharp printed pattern appear immediately when the board is dipped into the solution. When the board is lifted up, the whole photo-resist layer is being wash down from the surface of the solution. Leaving away nothing but bare copper on the board surface.

When PCB trace appear instanly when it is dip into the developer, it can indicate that the solution is too strong. Start off with low NaOH concentration, and increase a bit at a time. Experiment and obtain the correct mixture for the developer. Remember to dissolve the chemical fully when adding more chemical, before dipping the board into the solution.

5.   Etching

Material and Equipment

• Ferric Chloride powder

• distill or plain water

• gloove

• glass, plastic, wooden rod or old chopstick

• long container for the etchant

• a boarder container for boiling hot water below

• 3 litre of boiling water

• drilling machine

• plastic string

• developed PCB board

• container with water for washing

• detergent

Ferric Chloride FeCl3,

SENO 3200 (hexahydrate type)

Translated Instruction from German Language found on SENO 3200 iron iii-Chloride.

Long-proven etching agent for printed circuits, copper and high-grade steel, which already corrodes at ambient temperature and is almost for an unlimited period storable also in used condition. In the temperature range of 20-40 it is characterised by a good etching rate and a small under etching. With increase temperature increases both. Copper admission on the average 40-50g/Litre, etching rate 40-3µ/min

Caution: Injurious to health when swallowing. Far of children and food store. Rinse off immediately during contact with the eyes thoroughly with much water and physician consult. Marks with difficulty removable.

Content: 230g per pack for 0.5 to 1 Litre of etchant.

mixing FeCl3 with water

5.1 Etching introduction

Ferric Chloride is use to etch away copper surface on the PCB board. It is a very toxin chemical and is harmful to the environment. Please handle and dispose the chemical waste with care. It is dark yellowish in color and can stain your clothing.

Remember to wear protective gloves while handling FeCl3. Chemical is toxin and will cause skin irritation Wash skin with running water immediately when in contact with skin.

Stronger FeCl3 solution enables etching process to be faster.

When design PCB board, it may be a good idea to fill up with regions of copper. This is to minimise the area of copper surface to be etched away. With less copper to etched, it will also means that the solution can be effectively use to etch more PCB board.

   Where to buy them locally???

You can buy Ferric Chloride from Bell System, #03-12, Sim Lim Tower. Please do take care of our environment when disposing this chemical. The etching tray is again an old ice-cream box.

 Visit Dickson Chemicals,

the local chemical store in Singapore

Dickson Chemicals

www.dicksonchemical.com.sg

Tel: 6280 0468

Fax: 6281 1082

30 Shaw Road #05-05,

Singapore 367957

5.2 Etchant mixture

The solvent composite for making the etchant consist of

about 1 unit of Ferric Chloride FeCl3 is to

3 unit of water.

or about 1 unit of Ammonium Persulphate is to

5 unit of water.

Stir the mixture until FeCl3 is fully dissolved with the water.

mixing FeCl3 etching solution.avi (3.4MB)

warming up the FeCl3 solution

5.3 Warming up etchant

Warm up the FeCl3 solution on a tray (blue) filled with hot water. Temperature range from about 50°C to 60°C will be suitable to speed up etching process.

warming up the etchant solution.avi (3.6MB)

secure PCB board with string

or use scotch tape to secure string to the PCB board.

5.4 Board preparation for etching

Drill a small hole on the PCB board so that a string can be secure to the board. The string is use to position or pull out the PCB in the toxin solution.

or

A scotch tape can be used to secure the string to the PCB board.

PCB board etching until the unwanted copper is remove completely by the chemical.

5.5 Etching PCB

Immerse the PCB board slowly into the FeCl3 solution. Agitate the PCB by tilting the container to and fro gently, until the unwanted copper layer are properly etched away, leaving only the required region on the PCB. The process may take 15 – 60 minutes to complete. Process duration will depends on the concentration, temperature of the etchant solution.

 A video clip is available to help you visualise the process.

etching process 1.avi (2.8MB)

etching process 2.avi (2.7MB)

etching process 3.avi (2.9MB)

Etching method also plays a part in the etching speed. If you leave the board without any agitation, the process may takes hours. There are other method of agitation, for example by using bubble or spraying onto the copper surface. A good agitation equipment helps to speed up the process to merely a few minutes.

The etching effectiveness will be reduce if the solution is re-used for a number of times. Strong FeCl3 concentration and high temperature can increase the etching speed.

testing of different ways to resist copper from being etched by the chemical.

5.6 Testing various etch resist material

The photos simulate a developed PCB board masked with some scotch tape, masking tape, and text using oil based marker. The board is over-developed and is used for testing various etch resist materials.

The experiment shows that adhesive tapes and oil base marker can be implemented to perform as a mask to resist from the etchant.

Notes:

For commercial PCB fabrication it is important to leave a minimum spacing between the copper track depending on the PCB copper thickness. This is needed so that it have enough space for the etching to take place.

http://www.pcbuniverse.com/pcbu-tech-tips.php?a=4

Cu Weight         Min Recommended Space between copper features

1oz                     3.5mil (0.089mm)

2oz                     8.0mil (0.203mm)

3oz                     10mil (0.254mm)

4oz                     14mil (0.355mm)

washing PCB with detergent after etching.

5.7 Washing board condemned with FeCl3

Prepare a container of detergent solution to wash the PCB board condemned with chemical FeCl3. Detergent contain Sodium Carbonate or Sodium Hydroxide, which can neutralize FeCl3.

removing away the photo-resist green coating.

photo-resist coating removed, however the black marker writing is still on the board

contact cleaner is apply to tissue paper wiping away the marking.

washing chemical content on the board with running water.

PCB etching completed

5.8 Removing photo-resist coating and other stain

Photo-resist mask or marking of the traces can be removed using the NaOH developer. It is the same developer used during the developing process. Stronger solution can be use this time round as the etching is already completed. The protective coating is no more in use.

A cloth soak with the solution can be use to wipe on the PCB board surface to remove the coating.

For the marker stain, it can be remove using commercial available contact cleaner, alcohol, or thinner solution.

Rinse with water, clean and dry the PCB board.

wiping marker ink away from the copper.avi (2.8MB)

soaking FeCl3 in detergent before attempting to dispose this chemical waste.

5.9 Disposing toxin chemical

Ferric Chloride FeCl3 is a toxin chemical. Please consult your local authority for proper dispose of chemical waste product.

As recommended, detergent (or other baking soda) can be mixed to the FeCl3 solution. The mixture solution can easily produce bubble foam which can grow 10 times in volume. Lay waste paper under the container to prevent toxin overflowing out of the container onto the floor. Leave it to dry before disposing the waste.

Sodium carbonate (washing soda) or sodium hydroxide can be added to neutralize Ferric Chloride before proper disposal.

For information on the disposal of Ferric Chloride. Follow this link,

http://www.mgchemicals.com/techsupport/ferric_faq.html

one month after neutralizing FeCl3

semi-dry residue at the wall of the container.

6.   Cutting and Drilling

Material and Equipment

• dot punch or sharp tool

• drilling machine or hand drill

• 1mm, 1.5mm drill bits

• coping saw

• hand files

• penknife

• steel ruler

• bench clamp or support

Complete fabrication of smaller individual PCB board

6.1 Introduction to cutting and drilling

The etching is completed. The original artwork is arrange to maximise the use of the PCB board. 5 small PCB can be fabricated on the 15cm x 10cm board. 3 of the PCB pattern is not formed properly during the developing process, therefore only 2 PCB board can be extracted.

Hole is necessary to mount component (example: resistor, capacitor, inductor, board mount switch, DIP integrated circuit IC etc). Before drilling, a dot punch is used to mark the hole position. This serves as a shallow guide for the drill bit to align easily while drilling. Any other sharp pointed tool can be use to do the marking.

The drill is fitted with a 1mm drill bit. A typical hole size large enough for most components. A 1mm drill bit is thin and can break easily. Hold the drill steady and drill in straight slowly. The hole will be drilled with little force applied.

After the drilling is completed, the board outline is then marked with a steel ruler and a pen knife. Coping saw is used to cut the board out. The board will leave sharp bur edges after sawing the board. Use the hand file to de-bur the sharp edge.

The PCB board making is completed and is ready for use.

drilling holes for components.avi (2.8MB)

There is a market trend of shifting all electronics to surface mount type. Components are more compact and therefore reduces the overall size. Eventually it contributes to the reduce in cost in almost every aspect of the project. Cost reduce in component, PCB board, transportation, etc… . Although it is fairly difficult to solder, the convenience of making PCB board without the hazard of drilling holes make it very attractive to the home PCB fabrication. Soldering surface mount device (SMD) component is possible and requires some practices.

Talking about soldering SMD component, there is this interesting question I have once raised. Have you ever notice the perfect soldering in the industrial PCB? It took me quite an imaginary journey searching for machine to do a perfect soldered PCB board. In the PCB manufacturing industrial, they are using a grey solder paste/cream instead of the solder wire roll. Similar to a toothpaste it is actually a lot of tiny solid solder balls mixed with flux. The paste is spread onto the PCB soldering pad, where the leads or SMD component will be later place on. The paste should  keep cool when not in use; no refrigiration needed, with an expiry period of about a year.

The whole PCB board is then taken on a conveyer belt ride through the hot oven to melt the solder paste and flowing solder will occur. After melting the paste on the PCB, it is then cool, and the solder harden which results in a perfect soldered PCB board. This re-melting process is know as reflow.

Reflow soldering is very fast, a method suitable for mass production. Unlike using a soldering iron, there is no need to aim on the soldering pad, typical heating through gases. SMD component will align automatic themselves during the reflow. You may be interested in getting a reflow station, or reflow machine for high volume production. For a cheaper reflow solution at home, you can click down to this highly recommended website,

 http://www.sparkfun.com/tutorial/ReflowToaster/reflow-hotplate.htm. They have demonstrated how surface mount component are soldered to PCB using industrial standard. It is a very interesting and educational website. Hope that you will enjoy.

The wave soldering process, is another method used for mass soldering of the circuit. Quite interesting.

http://www.ami.ac.uk/courses/topics/0225_wave/index.html

More article on Wave and reflow soldering.

http://www.ibselectronics.com/pdf/pa/walsin/smt_notes.pdf

www.zianet.com/erg/SMT_Soldering.html

mounting of surface mount component.pdf

Reference for smd equipment for soldering production.

– smt equip,emt reference.pdf

– http://www.faze.co.za/Products.html

7.   Tinning and Masking

Material and Equipment

• solder flux

• soldering iron (flat tip is available)

• soldering stand with wetted sponge

• solder sucker

tinned PCB board.

finish PCB product

DTMF decoder circuit using MT8870DE

LM2576 dc-dc converter circuit

7.1 Tinning the copper surface

Copper will oxidize when expose to oxygen environment. Oxidization should be avoided as soldering is difficult on oxidization surface.

A thin layer of solder is coated on the copper surface to prevent oxidization. Apply solder to the copper surface with hot soldering iron and spread the liquified solder across the surface. Covering the copper surface with solder helps protect the copper from oxidization.

tinning PCB copper area.avi (3.0MB)

There are various type of commercial surface finish options for PCB board.

– HASL -Hot Air Solder Leveled (Low$)

– Immersion Tin (RoHS, Low$)

– Lead Free HASL -Hot Air Solder Leveled (RoHS, Mid$)

– ENIG -Electrodless Nickel Immersion Gold (RoHS, Mid$)

– Electroplated Gold (RoHS, Mid$)

– Immersion Silver (RoHS, Mid$)

Reference link:

http://www.nciproto.com/info/Surface_finish.htm

7.2 Masking PCB board

Masking can be applied to non-soldering area to protect the board from potential short circuit, oxidization and overflow of solder during soldering. The soldering would also be easier and nicer

It is not really necessary in home PCB fabrication, however if you want to give your board the professional touch, there is masking spray available in the market to lacquer the PCB board.

Click here for a short clip on “Apply a solder-resist mask to PCB“.

7.   Other Method of PCB making

<This is an OLD ARTICLE>

Laser printing, iron transfer artwork

Use Etch-resist pen

PCB patter transfer film

Milling PCB

Using etching machines for mass production.

bubble etching equipment

bubble Tank accessories for PCB board fabrication.

container to hold the Etching chemical.

A flat plastic container is used for developing the photo-resist PCB. Glass rod should be used to stir and mixed the chemical in distill water, because glass material does not have chemical reaction with most chemical.

air pump to sort of stir the liquid to quicken the etching process.

long stone rod to disperse air bubble

water tank or fish tank heater to warm up the water during etching process.

photo-resist PCB board 15cm x 10cm from Kinsten

Old Article:

Written by Lim Siong Boon, dated 03 Dec 2005.

The fabrication process was a failure. Photos was taken on the fabrication process. Unfortunately the photos were lost in the borrowed digital camera. Damn it, the pictures are lost for no reason. Should have retrieve the photos immediately after the photo taking.

The first fabrication was done in a friend’s company, selling and dealing with chemical stuff. He is Chee Keong, my good friend from Singapore Polytechnic. He is my very supportive of my project, and invited me to his company on a fine Saturday evening (Sep 2005) for my board fabrication. The place is great because he have all the chemical, tools and facilities I need to fabricate the PCB.

Sodium Hydroxide NaOH was used to developing the photo-resist board, and Sodium Persulphate was used to etch away the metal. Ferric Chloride is a more common chemical used for etching the board, it is a very toxin chemical and disposal needs careful attention. The chemical is a controlled item in Singapore and requires license to use the chemical. It is this reason that I insist to try something safer, like sodium persulphate. However after the trial, sodium persulphate doesn’t seems to perform. I have not yet figure out the reason, but would like to try out Ferric Chloride for my next trial. It is a dangerous chemical, so some knowledge research or revision is recommended before any attempt to use the chemical.

There are other alternative chemical used in PCB fabrication after some research on the internet.

Bubble etching concept

Trying to heat up the solution with the heater. It is slow and very troublesome. The air pump has to be glue to the bottom as it will tends to float and is unable to keep still. Cleaning is very troublesome because a lot of equipment is required for the etching.

After trying for 2 times, a simpler idea pops out of my mind. Shortcuts are for lazy people like me.

New IDEA

A new and simple etching setup that pops up on my mind.

Hair Dryer will provide the heat and agitation to speed up the etching process.

The flat lying plastic tray will provide minimum amount of chemical to be mixed for etching the PCB board, through means less wastage.

In the end, I ended up using an even easier method by placing the container of etchant solution on a tray of boiling water.

It works and have less minimum setup. Etching quality is just as nice.

Bill Of Materials, estimate to be S$60.00

1. Introduction to Reverse Engineering of electronic circuit board

Reverse engineering circuit board is definitely not a simply one day training lesson. It is not as simple as knowing it all simply from a search engine on the internet. It is a process which harness the years of experience accumulated in electronic design and studying of how other engineers design their circuits. While as tough as I may have describe, it does not means that there is no way to learn this skill.

There are many reason why we need to reverse engineer a circuit board. One reason that I enjoy doing, is to learn something from the board. In the early days of my engineering career, as a fresh graduate who have background about electronics but practically don’t even dare to design a circuit for commercial use. There was just not enough confident in myself to design something for the industries to use. It was also a time when I started to become curious of how a circuit works. As a fresh new hardware engineer in a R&D department, basically I start create circuit solution by copying. Copying design that I find from books, from electronic kits purchase from stores, from internet where many people uploaded for their projects. I was also fortunate to have a colleague who had had retired and was working for this small company that I was working in, who makes me felt like he is nagging, trying his very best to share his knowledge about electronics with me. Standing there listening to him teaching from the very basic, starting from the name of a component. Topic like, how to classify the type of switch SPST DPST DPDT,can seems boring. It can be quite an annoying thing, when he speaks about simple things (which I thought they were). The truth is those simple thing that I thought they were, are actually fundamentally important, I had realized. Over time I started to earn some insight which I didn’t really catch then during my polytechnic and university school days. The topic “Switch” that I wrote in another webpage is one of the simplest and most important topic that I think all electronic hardware engineer needs to know by hard.

Reverse engineering can be like looking at a piece of blank at first. The more newbie you are, the more you do not know where to start understanding the circuit. In this section, I will briefly go through the process of how a circuit board can be reverse engineered in a sequential process.

Circuits can looks like an art where almost every circuit seems so different. The truth is that many circuits are very similar in nature. There is a pattern that you can find in every circuit. Recognizing these pattern is important. The more pattern you know, the faster you are about to decode the circuit. Electronic is physics and physic is the same across the world we are now living in. People use the same knowledge, copy the same knowledge, ends up with circuits that are quite standardize across the design that we can find. First important concept that we can start with, is to know that there is a standard circuits in many of the design. Just like a rubber stamp, people tends not to reinvent the wheel. We design a circuit that works, and keep on using that same circuit pattern. Whenever we trace out the component connection, we will try to match these patterns that we are able to recognizing. As you might have realized by now, the prerequisite to master the skill of reverse engineering, is the skill of designing electronic circuits. Like wise the opposite is also true. Both reverse engineering and circuit design are skills that need to progress hand in hand.

Why Reverse Engineering?
– to learn how things work.
– to do something new or unique.
– test hardware’s specification, security and weaknesses.
– better control of the system.
– identify design failure, weak components due to current, voltage or heat.
– identify how product can be improved.

reference:
https://media.blackhat.com/bh-dc-11/Grand/BlackHat_DC_2011_Grand-Workshop.pdf
or BlackHat_DC_2011_Grand-Workshop.pdf

Removing Epoxy Encapsulation.
– hot air soften epoxy
– Chemical, MG Chemicals’ 8310 Conformal Coating Stripper (www.mgchemicals.com)

2. Recognizing Components

The most basic thing you need to recognize is the electronic components that you see on the circuit board. As a new engineer, you may find yourself floated with odd components that you have not seen before. Many newbie may recognize those component symbol that we read from the schematic, but may not be able to recognize them in the actual physical form in a real physical circuit.
The resistor component alone can comes with many sizes, shapes, and color. It is important to recognize them, and understand their differences in characteristic. In school, we usually take resistor as only a ohm value, and don’t bother about the precision of the resistor,  tolerance, and even wattage is often ignored. In a practical circuit design, there are reason why some resistor are bigger or why some are more precision. First thing first, ensure you can recognize each and every component on the circuit. Knowing their names and how they are classified can helps you speed up the time needed to identify them. It is also a reason why through out my other webpages, I try to use photo, and put down the possible names that can be use to identify the components. Identify as much components as you can. Resistor, Capacitor, Inductor, IC chips, fuse, diode, transistors, connectors, PCB board, etc…

Nowadays, modern circuit board uses more IC chips than passive components. All IC chip looks the same black encapsulation with various shape and size. The important thing is to examine the number that is printed on the chip itself. Without it, you will need more brain power and experience to decode the board. It is also a main reason why some manufacturers will find ways to erase the lettering on the IC chips. It is a means to increase the barrier for reverse engineering, which can reduce the probability of their circuit design being copied.

With the lettering on the IC chip, you can search for their datasheet on the internet. If you cannot find them in the search engine, you may like to try again, leaving out some lettering in the front or back in order to increase the probability to get a search hit. The latter section “looking out for the IC chip marking” delicate a section to improve your chance to discover the IC marking and the search for its datasheet.

Most modern circuits are design using surface mount components. They can be small and traditional color band scheme for a component like resistor cannot be use. For these SMD resistors, they are number coded. For bigger SMD resistor, they are number coded, similar to the color band scheme where the first few digit represent the actual digit, while the last digit represent the number of zeros. Smaller SMD resistor which has a smaller printed area print their value using a standard coded system. This standard coding system is known as EIA marking code. There is no way to determine the resistor value easily from the code. Fortunately, we do not have to remember it by hard. With a search through the internet, we just need to extract its value base on the code. There is also this free android apps call “ElectroDroid” which can allow you to key in the EIA code, and return you with the resistance value. The apps also contains many other features which can assist you in your reverse engineering process. For more information about resistors and capacitors classification, click on the respective links.

Recognizing the components is only the first step. Identifying component itself already requires a lot of experience and effort. Even after nearly two decades of working with electronics, I still do find components which I find it difficult to identify. Inductor and transformer is a component which I am still not able to overcome easily. Newer modern components being used in circuits, often curious me. It is a never ending learning process.

STEP 1:

Take a photo of the circuit board (top and bottom), and start to assign a reference designator (label numbering) for each of the components.
 

Use OpenOffice Impress to help you do the component part labelling on the photo of the circuit board (PCB).

For example, all resistor can have prefix R1, R2, R3, R… R46, capacitors C1, C2, C3, C… C56.

Document these parts on a OpenOffice Calc spread sheet with the following columns,

(S/N or component prefix label, Component type, Package, Marking, Part no., Manufacturers)

Try to fill up the columns with information as much as you can.

Check out

• Resistor Color Code, SMD Resistor Marking Code.
• Capcitor Code
• Inductor Color Code.

STEP 3:

STEP 3:

STEP 4:

STEP 5:

3. Mapping out the Traces

This is the most tedious part of the reverse engineer process. It is to map out how the components that you have identified earlier are connected. Component by component, we map out all the connection (known as traces).

Before starting the tracing process, it is important to recognize the PCB board type. I classify them as single layer, double layer and multilayer board.

The simplest board is the single sided PCB where one side of the board is consist of only the PCB trace routing, while the other side is the electronic components. Typically consist of mostly through holes components. Fairly simple to trace out the connection.

The second type is a double layered PCB board where traces can be found at both side of the board. Most of the time, through hole components are found on one side of the board while the surface mount component is found on the other side. Very often, traces are routed below through hole components and IC chip. This makes it impossible to trace out the connection using only our vision. Multi-meter’s function “continuity” is required to aid us to identify a connection (sometimes also known as the continuity tester). Basically is will buzz when the probes touch two points which is connected by a trace. You can also use a ohm meter function which reads a 0ohm when a connection is probed. I prefer the buzz, because while I focus my attention tracing the circuit, I do not have to look up in the multimeter screen to check for a connection. The buzz sound is much more convenient. Although it is a productive feature to use to trace connection, it is important to note how the “continuity” feature works. Depending on the multimeter, the buzz is set to sound at a certain ohm threshold. This means that a 10ohm resistor between two point, can cause a buzz from the multimeter, which may mislead you into thinking that the two point is shorted. Do keep this in mind during the probing process. Using visual and the continuity features together should help minimize mistake. Components that you typically need to take note is, sense resistor (usually bigger in size than the rest of the resistor), inductors, transformer, coil and any external connection or wiring to the board. Another common mistake is to probe the circuit without switching off the power supply. Ensure that all connection to the board are disconnected before tracing for connection.

The most difficult board to trace will be the multilayer boards. Typically for a 4 layer boards, most designer likes to allocate the middle layer for power traces like VCC and GND. It is not a definite, but just a high possibility base on the experience of looking at other circuit boards and also some common circuit theory. Doing reverse engineering requires you to think a lot as if you are the designer designing the board that you are hacking. For a multilayer board, it is normally near to impossible to trace the board using visual. Matching of component pins connection is normally done for the whole of the circuit board. Matching one pin to the rest of the pin, one at a time. Sometimes with the understanding of the component, and some experience as a designer, you might be able to shorten the process. There will be zones that you will instinctively that there is no need to try.

Draw out the components position, and how they are connected. Taking a picture of the circuit helps you to trace easier. Sometimes I will superimpose the routed trace with the components in order to see the connection better. Label all the components, and name the trace once you are able to identify its function.

Power supply traces are the simplest to start with. This is because we usually knows where the power line is connected to the circuit. From there we can trace out where the power line goes to. From the power line, we will be able to trace out the next stage which is typically the voltage regulators. For a AC power line, usually a rectifier can be located a before it reaches the voltage regulator. These suggestion assumes typical design, it will be up to you to recognize it yourself because there are just too many variation of circuits designed.

Studying the datasheet of the IC chip on board can also help you to recognize connection. Arrange the component symbol into the standard stamp circuit configuration that you can recognize. Common standard circuit like input circuit, pull up, driver circuit using transistor, relay circuits, voltage regulator, etc… can easily be recognize. Draw them out in a format that helps you to recognize the circuit module functionality.

The process is complex, and it is a never ending topics on reverse engineering. The more you reverse engineer the more you will learn and improve your techniques, finding new ways to decode and learn how other circuits are designed.

Looking at IC chip marking

Looking out for the IC chip marking

IC chip is getting smaller and smaller. Many small chip can only be coded with only 3-4 letterings only. This is the IC marking which represent a part number from the manufacturer.

References for searching base on the letter/number marking on the IC,
– Database search, http://www.ecadata.de/searchnew/
– smd codes catalog 2012, SMD-codes Active SMD semiconductor components marking codes
– smd marking, http://www.satcure-focus.com/design/page2.htm
– http://www.dl7avf.info/charts/smdcode/c3.html
– http://www.sos.sk/pdf/SMD_Catalog.pdf

Marking code search from manufacturer’s website
Texas Instruments, http://www.ti.com/general/docs/partmarking/partmarkinghome.jsp
Cross competitor search: http://focus.ti.com/general/docs/searchhome.tsp

Fairchild, http://www.fairchildsemi.com/topmark/

Analog Device, http://search.analog.com/search/default.aspx

NXP, http://www.nxp.com/packages/

Cross Reference next to the search box, type the part number and search: http://www.st.com/web/en/ordering/buy_from_distributors.html?s_searchtype=keyword
Product selector: http://www.st.com/stonline/stappl/productcatalog/app?page=productSelector

Microchip, http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1924&dDocName=en544123
Product selector or Cross competitor search: http://www.microchip.com/maps/search2.aspx

Looking out for the logo on the IC chip.

Analog Devices
Atmel
BI Technologies
Burr Brown
Cirrus Logic
Cypress Semiconductors
Dallas Semiconductor
Diotec
Fairchild Semiconductor
Holtek Microelectronics
Intersil
International Rectifier
Maxim
Microchip
Motorola
NEC
National Semiconductor
NXP
Semtech
STMicroelectronics
Texas Instruments

References for IC manufacturer logos,
– http://www.elnec.com/support/ic-logos/
– http://www.classiccmp.org/rtellason/logos/semiconductorlogos.html
– http://www.advanced-tech.com/ic_logos/ic_logos.htm or pdf
– http://web.archive.org/web/20040401171928/http://www.elektronikforum.de/ic-id/

1. How much is the electricity tariff rate costing us?

The Singapore electricity tariff rate has been rising steadily 18.03¢ (as of Apr 2009) to 27.28¢ (as of Jul 2011) ; A wopping 151% increase in tariff rate. How does this tariff rate relates to the electrical appliances that we are using at home?

The following example show you how to compute the cost of our electricity cost.

Assuming a device consuming 10W 24hr per day for one whole month.

Total energy consumption in a single day = 10W x 24hr = 240 Whr

Total energy consumption in a month = 240Whr x 31days = 7440 Whr = 7.44kWh

The bill for 7.44kWh of electricity consumption will be = 7.44kWh x $0.2728/kWh = $2.029632

This means that the appliance consuming 10W will cost me $2/mth.

Appliance consuming 20W will cost me $4/mth.

Appliance consuming 100W will cost me $20/mth.

If the tariff rate go up, the cost of electricity per watt will relatively increase as well.

What can I do to reduce my electricity bills, at the same time conserve our global energy resource?

First I have to understand my energy consumption in my own house, by doing a simple energy audit.

Being energy conscious will be the very first step to start save energy.

The energy audit of my home shown on this page will be based on the latest tariff rate of 27.28¢ (as of Jul 2011).

Our electricity tariff in Singapore since 2009.

Energy cost: S$0.1803/kWh as on 1st Apr 2009

Energy cost: S$0.1928/kWh as on 1st Oct 2009

Energy cost: S$0.2169/kWh as on 1st Oct 2009

Energy cost: S$0.2287/kWh as on 1st Jan 2010

Energy cost: S$0.2356/kWh as on 1st Apr 2010

Energy cost: S$0.2413/kWh as on 1st Jul 2010

Energy cost: S$0.2334/kWh as on 1st Oct 2010

Energy cost: S$0.2410/kWh as on 1st Jan 2011

Energy cost: S$0.2558/kWh as on 1st Apr 2011

Energy cost: S$0.2728/kWh as on 1st July 2011

Energy cost: S$0.2698/kWh as on 1st Oct 2011

Energy cost: S$0.2759/kWh as on 1st Jan 2012

References:

– http://www.energysave.sg/

– http://www.spservices.com.sg/

– http://www.ema.gov.sg/Electricity/new/ (more tips to save energy)

– Singapore electricity tariff rate Jun 2011

– Singapore electricity tariff rate Jan 2012

Calculator for computing Appliance’s Electricity Cost

2. Power Meter

The beginning of this page starts with my handy portable power meter. It will be the most important instrument to help me measure the power consumption of the everyday appliances in my house. It was a coincidence that I brought my power meter. I had always like to have such a power meter to measure power consumption for fun and knowledge; the cost of such a gadget was rather expensive to be purchase just for fun. I got myself this power meter which is inexpensive. I like the huge display; the numbers are easy to read. It is very simple to use; just plug in the appliances that you want to measure and switched on the power. The function button can be pressed to cycle through the list of measurement parameters as follows.

1) Wattage, display the power consumption of the appliance

2) Display the energy consumption in terms of dollar cost

3) kWh (kilo Watt Hour), accumulated energy since operation.

4) Number of days, hours since measurement begins. (This helps to check against the kWh energy consumed and the accumulated cost run since measurement starts)

5) Voltage (Vrms measurement usually range from 220 – 240Vac)

6) Frequency (always 50Hz for measurement in Singapore)

7) Current (High current device usually requires thicker cable guage. High current flowing through thin cables can generate heat which leads to energy loss, and may result in fire.)

8) Power factor (PF range from 0.0 – 1.0. PF near to 1.0 indicates that the appliance has a better current to power efficiency, consuming all the power that was drawn) http://en.wikipedia.org/wiki/Power_factor

9) Highest/lowest wattage detected. (The meter when monitoring the appliance over a long period of duration, is able to show the highest/lowest wattage detected)

10) Key in the latest electricity tariff rate..

11) Reset button to reset the measurements.

The features on the power meter are more than enough to measure household appliances. There is a current limit of about 13A which the meter can handle; the meter will give off a warning beep sound and cut of the power if it is overloaded. I just love this power meter, cheap and good enough for my energy audit.

It was when I started measuring my household appliance, that I started to learn the appliances that are energy consuming. It is difficult to judge base on the device, even though I am a trained engineer in electronics circuit design. I was shocked to find that many appliances are poorly design in terms of energy conservation. This is also the reason why I started this page. I would like to find out the power consumption of the appliance in a typical home. The step to start saving our earth starts by being aware of our energy consumption; this is also known as our carbon footprint.

Besides measuring power consumption, this power meter is also very useful in my area of engineering works.

This portable power meter helps to verify my electrical installation works. There are also times where 110Vac is used in our 230Vac electrical system in Singapore. This meter helps to check if the voltage step-down transformer installation is correct, before we plug in any expensive 110Vac equipment from oiverseas. It can also be used to check the wattage of your equipment so that the accessories with the correct wattage can be purchased and installed.

Power factor (range 0.0 to 1.0) indicates the efficiency of the current drawn from the power station. Poor power factor is cause by your inductive equipment (eg. Fridge, Fan, Motor etc..) at home or factory. A power factor of 1.0 is the best, indicating the lowest possible current drawn. A reading of 0.6PF or below indicates a poor power factor, and you will expect the current drawn to be higher. The good news is, it can be improve by installing a capacitor across the power line.

This meter measures the power factor which allows me to add in the correct amount of capacitance to correct the power factor close to 1.0. Power factor of 1.0 means that the current drawn by my equipment will be minimum. The meter will also show the drop in the current drawn, before and after the capacitance installation. For more technical information on correcting power factor, I have another delicated page explaining all the details.

http://www.siongboon.com/projects/2012-01-24_power_saver/index.html

In the course of designing products for the industries, this meter also helps me to verify my design in terms of the energy consumption. It helps me to improve the design, allowing the product to consume less energy.

With this measuring instrument, we will have a better idea of how we can improve our energy consumption.

   “If you can not measure it, you can not improve it.”
                                                                     Lord Kelvin (1824-1907)

I hope this page can provide the awareness to get you conscious about your carbon footprint. It will also serve as a platform to compare the consumption with the available energy saving products. The journey shall starts with my power meter. Let’s get started.

References:

– www.saveone.com.sg

My portable power meter packed with many features (description details on the left). Measure power from the plug.

1) Wattage 2) Accumulated electricity expense
3) kWh 4) Records of the number of Days & Hours since measurement starts
5) Voltage 6) Frequency 7) Current 8) Power factor
9) Highest/Lowest wattage detected
10) Entering the electricity tariff rate costing.

This power meter is purchased from .

Acknowledgement: some of the pictures on this page were taken from saveOne website. saveOne is a local company in Singapore, specialising in energy saving products and consultation services. They are also selling their various patented energy saving lightings products to promote green building to the industrial, hence reducing our carbon footprint in Singapore.

Website: www.saveone.com.sg , Email: sales@saveone.com.sg

Address: 63 Hillview Avenue, #08-01, Lam Soon Industrial Building, Singapore 669569.
Tel: +65 6764 3333, Fax: +65 6862 6277

Other brand of power meter available in Sim Lim Tower (Sim Lim Tower, 10 Jalan Besar 208787)

3. Home Appliances

Power Consumption

Note: the indicated elecrical costing is using the triff rate of $0.30/kWh

This is my electrical bill for my HDB house for the month of March 2012 from SP Services. The power consumption is estimated to be 363kWh which accounts to a bill of S$100.15. This is an estimation base on our electricity consumption for the pass few months. The tariff rate is 0.2759 for this quarter Jan-Mar 2012. I am trying to measure all my appliances to see if I can estimate near to the indicated consumption of 363kWh per month. The list of contribution would propably comes from the following devices. – Fridge – Aircon – Fan – Computer – TV and entertainment system – Washing machine – Lights – Radio It is time to find out the main culprit.

Home Lightings

Energy saving LED and Fluorescent lamp

Check out the various energy saving lamps here.

http://www.siongboon.com/projects/2011-04-17%20lamp%20bulb/index.html

Hot/Warm Water Dispenser

Model: Bio Pure (KEN2)

Typical standby power consumption is 6.8W	When dispensing water, the wattage shoot up to 21W	Total energy consumption for 63 days + 1 hour operation totals up to about 60.91kwh costing S$17.15

Standby power: 3.5W

Typical: 6.9W (wattage), 0.077A (current), 0.36PF (power factor)

Highest Wattage detected: 2256W

Low Wattage detected: 3.5W

AC indicator lamp

Hardly any wattage and current detected from the AC indicator lamp found on the multi socket adaptor..

Wireless Door Bell

Model: Sonik

Standby power is 1.2W

Even if the loud door bell ring is activated, the consumption still remains at 1.2W.