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Barcode Decoder Source Code

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chingB

Joined: 29 Dec 2003
Posts: 81

Barcode Decoder Source Code

Posted: Sat Jul 09, 2005 12:56 am

Hi,

I am sharing my barcode decoder source code. I guess this would be helpful in the community.

I use a Barcode OEM Slot Type Module from FameTech or Tysso at http://www.barcode-manufacturer.com/ or at http://www.fametech.com.tw/. The exact part number is SR-070 and I use the infra-red models. You can also use 1022WM from Cipher Lab at http://www.cipherlab.com/en/.

The decoder source code:

Code:

#define ZERO_VAL 0
#define ONE_VAL 1
#define TWO_VAL 2
#define THREE_VAL 3
#define FOUR_VAL 4
#define EIGHT_VAL 8

#define ROW_INDEX 4
#define COL_INDEX 10
#define MODULO_43 43 // barcode check digit calculation

#define REVERSE_SWIPE 110 // the badge id is swipe reverse
#define FORWARD_SWIPE 111 // the badge id is swipe forward

#define BARCODE_DATA_COUNT 8 // to char data per badge id
#define BARS_PER_CODE 5 // number of bars per char

// number of spaces per char
#define SPACES_PER_CODE ((BARS_PER_CODE) - (ONE_VAL))

// half the barcode data count
#define HALF_BARCODE_DATA_COUNT ((BARCODE_DATA_COUNT) / (TWO_VAL))

// maximum number of bars per badge id
#define MAX_BAR_COUNT ((BARCODE_DATA_COUNT) * (BARS_PER_CODE))

// maximum number of spaces per badge id
#define MAX_SPACE_COUNT ((MAX_BAR_COUNT) - (ONE_VAL))

//----------------//
// T3CON Register //
//----------------//
#define T3CON_BASE 0xFB1
#define T3CON ((unsigned int *)T3CON_BASE)

boolean CaptureMode = FALSE; // FALSE-Falling, TRUE-Rising capture
boolean BarStart = FALSE; // TRUE-barcode capture started
boolean BarEnd = FALSE; // TRUE-barcode capture ended
boolean SkipSpaceDone = FALSE; // TRUE-skip first space barcode capture

int BarCnt = ZERO_VAL; // bars counter
int SpaceCnt = ZERO_VAL; // space counter
int16 BarTable[MAX_BAR_COUNT]; // bars 16-bit time capture value
int16 SpaceTable[MAX_BAR_COUNT]; // spaces 16-bit time capture value

byte BarcodeTable[BARCODE_DATA_COUNT]; // decoded barcode data
byte RawBarTable[BARCODE_DATA_COUNT]; // raw bar data table
byte RawSpaceTable[BARCODE_DATA_COUNT]; // raw space data table

byte BarPatternTable[COL_INDEX] = {
17, 9, 24, 5, 20, 12, 3, 18, 10, 6
};

byte RevBarPatternTable[COL_INDEX] = {
17, 18, 3, 20, 5, 6, 24, 9, 10, 12
};

byte Code3of9Table[ROW_INDEX][COL_INDEX] = {
{'K','L','M','N','O','P','Q','R','S','T'},
{'A','B','C','D','E','F','G','H','I','J'},
{'1','2','3','4','5','6','7','8','9','0'},
{'U','V','W','X','Y','Z','-','.',' ','*'}
};

// bars and space average time variables
typedef struct BarSpaceAveStruct
{
int16 BarsAverageTime;
int16 SpacesAverageTime;
} BAR_SPACE_AVE_STRUCT;

boolean ClockTick = FALSE;
int TickCnt = ZERO_VAL;

#int_timer0
void timer0_isr(void)
{
TickCnt++;

if ( TickCnt > THREE_VAL
&& ClockTick == FALSE)
{
ClockTick = TRUE;

// output toggle PIN_A0 (LED Blinker)
#asm
BCF 0xF92.0
BTG 0xF89.0
#endasm
}
clear_interrupt(int_timer0);
}

#int_timer1
void timer1_isr()
{
// timer overflow for no barcode data to capture
disable_interrupts(int_timer1);
if (BarStart == TRUE)
{
BarStart = FALSE; // reset bar capture to initial state
SkipSpaceDone = FALSE; // reset skip space to capture first space
CaptureMode = FALSE; // reset to falling edge capture

BarEnd = TRUE; // barcode capture has ended
BarCnt = ZERO_VAL; // reset bars counter
SpaceCnt = ZERO_VAL; // reset spaces counter
}
clear_interrupt(int_timer1);
}

#int_ccp1
void ccp1_isr()
{
if ( BarCnt >= MAX_BAR_COUNT
&& SpaceCnt > MAX_SPACE_COUNT)
{
// disable CCP1 if bars and spaces count exceeds maximum count
disable_interrupts(int_ccp1);
}

if (CaptureMode == FALSE) // falling edge capture (bars)
{
CaptureMode = TRUE;
if (BarStart == TRUE)
{
BarTable[BarCnt++] = CCP_1;
}
else
{
BarStart = TRUE;
clear_interrupt(int_timer1);
enable_interrupts(int_timer1);
}
}
else // rising edge capture (spaces)
{
CaptureMode = FALSE;
if (SkipSpaceDone == TRUE)
{
SpaceTable[SpaceCnt++] = CCP_1;
}
else
{
SkipSpaceDone = TRUE;
}
}

// toggle capture CCP1CON mode select bit
#asm
MOVLW 0x01
XORWF 0xFBD, F
#endasm

// reset timer1
set_timer1(ZERO_VAL);
clear_interrupt(int_ccp1);
}

void init_mcu(void)
{
delay_ms(1000); // delay for 1 seconds (stabilized MCU?)

output_float(PIN_C2); // set to input for CCP1 capture

clear_interrupt(int_timer1);
clear_interrupt(int_ccp1);

setup_adc_ports(NO_ANALOGS); // setup PortA to digital I/O
setup_ccp1(CCP_CAPTURE_FE); // set CCP1 to falling edge capture

setup_timer_1(T1_INTERNAL | T1_DIV_BY_8); // 20M/(4*8*65536)
set_timer1(ZERO_VAL);

clear_interrupt(int_timer0);
setup_timer_0(RTCC_INTERNAL | RTCC_DIV_16); // 20M/(4*16*65536)
set_timer0(ZERO_VAL);

enable_interrupts(INT_CCP1); // enable CCP1 interrupt on falling edge
enable_interrupts(int_timer0);
enable_interrupts(global); // enable global interrupt

output_low(PIN_A0);
return;
}

void clear_barcode_buffers(void)
{
int Idx;

for (Idx = ZERO_VAL;
Idx < MAX_BAR_COUNT;
Idx++)
{
BarTable[Idx] = ZERO_VAL;
SpaceTable[Idx] = ZERO_VAL;
}

for (Idx = ZERO_VAL;
Idx < BARCODE_DATA_COUNT;
Idx++)
{
BarcodeTable[Idx] = ZERO_VAL;
RawBarTable[Idx] = ZERO_VAL;
RawSpaceTable[Idx] = ZERO_VAL;
}

return;
}

void display_code(void)
{
int Idx;

printf("\n\rBarcode = ");
for (Idx = ZERO_VAL;
Idx < BARCODE_DATA_COUNT;
Idx++)
{
printf("%c",BarcodeTable[Idx]);
}

return;
}

BAR_SPACE_AVE_STRUCT get_average_time(int BarIdx, int SpaceIdx)
{
int Idx;
BAR_SPACE_AVE_STRUCT Midean;

*(unsigned int32 *)&Midean = ZERO_VAL;

for(Idx = ZERO_VAL;
Idx < BARS_PER_CODE;
Idx++)
{
Midean.BarsAverageTime += BarTable[BarIdx + Idx];

if (Idx < SPACES_PER_CODE)
{
Midean.SpacesAverageTime += SpaceTable[SpaceIdx + Idx];
}
}

Midean.BarsAverageTime /= BARS_PER_CODE;

Midean.SpacesAverageTime /= SPACES_PER_CODE;

return Midean;
}

void get_raw_code(void)
{
int BarIdx, SpaceIdx;
int Idx, TableIdx;
byte BarPattern, SpacePattern;
BAR_SPACE_AVE_STRUCT Midean;

BarIdx = ZERO_VAL;
SpaceIdx = ZERO_VAL;

for (TableIdx = ZERO_VAL;
TableIdx < BARCODE_DATA_COUNT;
TableIdx++)
{
BarPattern = ZERO_VAL;
SpacePattern = ZERO_VAL;
Midean = get_average_time(BarIdx, SpaceIdx);

for (Idx = ZERO_VAL;
Idx < BARS_PER_CODE;
Idx++)
{
BarPattern <<= ONE_VAL;
if (BarTable[BarIdx] > Midean.BarsAverageTime)
{
BarPattern |= ONE_VAL;
}

if ( SpaceIdx < MAX_SPACE_COUNT
&& Idx < SPACES_PER_CODE)
{
SpacePattern <<= ONE_VAL;
if (SpaceTable[SpaceIdx] > Midean.SpacesAverageTime)
{
SpacePattern |= ONE_VAL;
}
}

BarIdx++;
SpaceIdx++;
}

RawBarTable[TableIdx] = BarPattern;
RawSpaceTable[TableIdx] = SpacePattern;
}

return;
}

byte reverse_special_char_space(int Spaces)
{
if (Spaces == 14)
return 7;
else if (Spaces == 13)
return 11;
else if (Spaces == 11)
return 13;
else if (Spaces == 7)
return 14;
else
return Spaces;
}

byte get_code_3of9(byte BarPattern, byte SpacePattern, boolean Mode)
{
byte Result='@';
int ColIdx, RowIdx;

if (BarPattern == ZERO_VAL)
{
if (Mode == FORWARD_SWIPE)
SpacePattern = reverse_special_char_space(SpacePattern);

if (SpacePattern == 14)
return '$';
else if (SpacePattern == 13)
return '/';
else if (SpacePattern == 11)
return '+';
else if (SpacePattern == 7)
return '%';
else
return Result;
}

else
{
for (RowIdx = ZERO_VAL;
RowIdx < ROW_INDEX;
RowIdx++)
{
if (SpacePattern == (ONE_VAL << RowIdx))
{
for (ColIdx = ZERO_VAL;
ColIdx < COL_INDEX;
ColIdx++)
{
if ( Mode == REVERSE_SWIPE
&& BarPatternTable[ColIdx] == BarPattern)
{
return Code3of9Table[RowIdx][ColIdx];
}
else if ( Mode == FORWARD_SWIPE
&& RevBarPatternTable[ColIdx] == BarPattern)
{
return Code3of9Table[THREE_VAL - RowIdx][ColIdx];
}
else
#asm nop #endasm
}

break;
}
}

return Result;
}
}

byte get_ref_code3of9(byte ch)
{
if ( ch >= '0' && ch <= '9')
return (ch - 48);
else if (ch >= 'A' && ch <= 'Z')
return (ch - 55);
else if (ch == '-')
   return 36;
else if (ch == '.')
   return 37;
else if (ch == ' ')
   return 38;
else if (ch == '$')
   return 39;
else if (ch == '/')
   return 40;
else if (ch == '+')
   return 41;
else if (ch == '%')
   return 42;
else return 100;
}

boolean get_check_digit(void)
{
byte Idx, BarData;
byte CheckDigit=0;

for (Idx = ONE_VAL;
Idx < BARCODE_DATA_COUNT - TWO_VAL;
Idx++)
{
BarData = BarcodeTable[Idx];
CheckDigit += get_ref_code3of9(BarData);
}

BarData = BarcodeTable[BARCODE_DATA_COUNT - TWO_VAL];

if ((CheckDigit % MODULO_43) == get_ref_code3of9(BarData))
return TRUE;

return FALSE;
}

void reverse_barcode_table(byte *Table)
{
byte Idx1, Idx2;
byte ch;

Idx2 = BARCODE_DATA_COUNT - ONE_VAL;
for (Idx1 = ZERO_VAL;
Idx1 < HALF_BARCODE_DATA_COUNT;
Idx1++, Idx2--)
{
ch = Table[Idx1];
Table[Idx1] = Table[Idx2];
Table[Idx2] = ch;
}

return;
}

void interpret_code(void)
{
int Idx;

for (Idx = ZERO_VAL;
Idx < BARCODE_DATA_COUNT;
Idx++)
{
BarcodeTable[Idx] = get_code_3of9(RawBarTable[Idx],
RawSpaceTable[Idx],
REVERSE_SWIPE);
}

if (get_check_digit() == FALSE)
{
for (Idx = ZERO_VAL;
Idx < BARCODE_DATA_COUNT;
Idx++)
{
BarcodeTable[Idx] = get_code_3of9(RawBarTable[Idx],
RawSpaceTable[Idx],
FORWARD_SWIPE);
}

reverse_barcode_table(BarcodeTable);
if (get_check_digit() == FALSE)
{
// error reading badge id
printf("\n\rBarcode Read Error!");
clear_barcode_buffers();
}
else
display_code(); // display badge id
}
else
display_code(); // display badge id

clear_interrupt(int_ccp1); // clear CCP1 interrupt flag
enable_interrupts(int_ccp1); // re-enable CCP1 interrupt

return;
}

The main loop:

Code:

void main(void)
{
int T3ConVal;

init_mcu(); // initialize mcu
clear_barcode_buffers(); // clear all buffers

T3ConVal = *T3CON; // read T3CON register
T3ConVal &= 0x9F; // timer1 is clock source for CCP1 module
*T3CON = T3ConVal; // update T3CON register

while (TRUE)
{
if (ClockTick == TRUE)
{
TickCnt = 0;
ClockTick = 0;
}

if (BarEnd == TRUE)
{
BarEnd = FALSE;
get_raw_code(); // get raw code of captured data
interpret_code(); // interpret captured data
}
}
}

The Serial Output:

Code:

\0A
Barcode = *RB1231*\0A
Barcode Read Error!\0A0D
Barcode Read Error!\0A\0D
Barcode Read Error!\0A\0D
Barcode Read Error!\0A\0D
Barcode Read Error!\0A\0D
Barcode Read Error!\0A\0D
Barcode Read Error!\0A\0D
Barcode = *RB1231*\0A \0D
Barcode = *RB1231*\0A\0D
Barcode = *RB1231*\0A\0D
Barcode = *RB1231*\0A\0D
Barcode = *MB2710*\0A\0D
Barcode Read Error!\0A0D
Barcode = *MB2710*\0A \0D
Barcode Read Error!\0A0D
Barcode = *MB2710*\0A \0D
Barcode Read Error!\0A0D
Barcode = *MB2710*\0A \0D
Barcode = *RB1231* \0D

Hope this would help.
Thank you.
-

grinch

Joined: 06 Feb 2006
Posts: 2

barcode reader to pic16f877a
Posted: Mon Feb 06, 2006 5:32 am

hi chingB! i have project...theres a barcode reader(ps/2) and its connected to a pic16f877 any idea about that...?

grinch

Joined: 06 Feb 2006
Posts: 2

barcode reader to pic16f877a
Posted: Mon Feb 06, 2006 6:02 am

hi! do you a schematic diagram of what kind of ic's u r are using? can i see it..

FGiordani

Joined: 25 Dec 2005
Posts: 4

Re: Barcode Decoder Source Code
Posted: Thu Feb 16, 2006 10:12 am

Hi, I'm Brazilian.I need of your hardware schematic of barcode circuit. This code work for PIC16F877? Which Microchip use? Thanks

PCM programmer

Joined: 06 Sep 2003
Posts: 21708


Posted: Thu Feb 16, 2006 12:36 pm

ChingB has not posted on the forum for 6 months. He has probably left the forum.

chingB

Joined: 29 Dec 2003
Posts: 81

Posted: Fri Mar 31, 2006 12:23 am

PCM programmer wrote:

ChingB has not posted on the forum for 6 months. He has probably
left the forum.

Sorry Guys I've been busy lately with my company projects.

I am now working with BitMicro (http://www.bitmicro.com) as a firmware engineer.

As of the moment I don't have a spare time but I will try my best to be part of the community esp. I luv doing firmware programming using PIC.

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