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Barcode Decoder Source Code

 
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chingB



Joined: 29 Dec 2003
Posts: 81

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Barcode Decoder Source Code
PostPosted: Sat Jul 09, 2005 12:56 am     Reply with quote

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

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barcode reader to pic16f877a
PostPosted: Mon Feb 06, 2006 5:32 am     Reply with quote

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

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barcode reader to pic16f877a
PostPosted: Mon Feb 06, 2006 6:02 am     Reply with quote

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

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Re: Barcode Decoder Source Code
PostPosted: Thu Feb 16, 2006 10:12 am     Reply with quote

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: 20318

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PostPosted: Thu Feb 16, 2006 12:36 pm     Reply with quote

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



Joined: 29 Dec 2003
Posts: 81

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PostPosted: Fri Mar 31, 2006 12:23 am     Reply with quote

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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