Generating barcodes on LCD display

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1

This demonstrates generation of Code-39 barcodes on an LCD display.
LCD display is this http://www.sparkfun.com/products/9351
With SerialGLCD download | SourceForge.net and serialGLCD library for Arduino download | SourceForge.net
Text 7 characters or less can be generated on screen. The barcode is perfectly readable with Zbar.
The code is somewhat rough:

#include <serialGLCD.h>
#include <ctype.h>
  serialGLCD lcd;
  char ctl[]="NwNnWnWnN";
  char zero[]="NnNwWnWnN";
  char one[]="WnNwNnNnW";
  char two[]="NnWwNnNnW";
  char three[]="WnWwNnNnN";
  char four[]="NnNwWnNnW";
  char five[]="WnNwWnNnN";
  char six[]="NnWwWnNnN";
  char seven[]="NnNwNnWnW";
  char eight[]="WnNwNnWnN";
  char nine[]="NnWwNnWnN";
  char A[]="WnNnNwNnW";
  char B[]="NnWnNwNnW";
  char C[]="WnWnNwNnN";
  char D[]="NnNnWwNnW";
  char E[]="WnNnWwNnN";
  char F[]="NnWnWwNnN";
  char G[]="NnNnNwWnW";
  char H[]="WnNnNwWnN";
  char I[]="WnNnNwWnN";
  char J[]="WnNnNwWnN";
  char K[]="WnNnNnNwW";
  char L[]="NnWnNnNwW";
  char M[]="WnWnNnNwN";
  char N[]="NnNnWnNwW";
  char O[]="WnNnWnNwN";
  char P[]="NnWnWnNwN";
  char Q[]="NnNnNnWwW";
  char R[]="WnNnNnWwN";
  char S[]="NnWnNnWwN";
  char T[]="NnNnWnWwN";
  char U[]="WwNnNnNnW";
  char V[]="NwWnNnNnW";
  char W[]="WwWnNnNnN";
  char X[]="NwNnWnNnW";
  char Y[]="WwNnWnNnN";
  char Z[]="NwWnWnNnN";
  char sp[]="NwWnNnWnN";
  int xc = 1;
   void intr(char *c){
    int n;
    for(n = 0;n < 9;n++){
      switch(c[n]){
        case 'W': lcd.drawLine(xc, 0, xc, 64, 0); delay(7); lcd.drawLine(xc+1, 0, xc+1, 64, 0); delay(6); xc+=2; break;
        case 'N': lcd.drawLine(xc, 0, xc, 64, 0); delay(7); xc++; break;
        case 'w': xc+=2; break;
        case 'n': xc++; break;
      }
     if(xc > 128){Serial.println("OVRFLW");}
    }
    xc++;
  }
  void str(char *s){
    char a;
    char *x;
    for(a = 0;a < strlen(s);a++){
       switch(tolower(s[a])){
         case '*': x=ctl; break;
         case 'a': x=A; break;
         case 'b': x=B; break;
         case 'c': x=C; break;
         case 'd': x=D; break;
         case 'e': x=E; break;
         case 'f': x=F; break;
         case 'g': x=G; break;
         case 'h': x=H; break;
         case 'i': x=I; break;
         case 'j': x=J; break;
         case 'k': x=K; break;
         case 'l': x=L; break;
         case 'm': x=M; break;
         case 'n': x=N; break;
         case 'o': x=O; break;
         case 'p': x=P; break;
         case 'q': x=Q; break;
         case 'r': x=R; break;
         case 's': x=S; break;
         case 't': x=T; break;
         case 'u': x=U; break;
         case 'v': x=V; break;
         case 'w': x=W; break;
         case 'x': x=X; break;
         case 'y': x=Y; break;
         case 'z': x=Z; break;
         case ' ': x=sp; break;
         case '0': x=zero; break;
         case '1': x=one; break;
         case '2': x=two; break;
         case '3': x=three; break;
         case '4': x=four; break;
         case '5': x=five; break;
         case '6': x=six; break;
         case '7': x=seven; break;
         case '8': x=eight; break;
         case '9': x=nine; break;
         default : x=sp;
       }
       intr(x);
    }
  }
void setup(){ 
  Serial.begin(115200);
  delay(1500);
  lcd.resetLCD();
  delay(250);
  unsigned char x,y;
  for(x = 0;x < 128;x++){
    for(y = 0;y < 64;y++){
      lcd.togglePixel(x, y, 1);
    }
  }
  str("*TEST*");
}
void loop(){

}

Cam0Pic12-05-04_23.21.59.jpg

2

Pretty cool. :slight_smile:

3

Yes! And easier to implement then I thought.
But the code needs alot of work, including more efficient lookup table packing and putting the huge tables in PROGMEM.

4

My android device with the Barcode Scanner was able to scan the photo. It's the text TEST, right? :wink:

5

including more efficient lookup table packing

The codes can be optimized quite easily

You have 4 codes
W = Wide line
N = narrow line
w= wide space
n = narrow space

char zero[]="NnNwWnWnN";

Because line and space are alternating you can replace this scheme with 2 codes if you keep track of the mode (Line | Space) in the code.

W = Wide
N = narrow

char zero[]="NNNWWNWNN";

2 codes ?? thats binary so we can replace W=1 and N=0

char zero[]="000110100";

9 bits can be encoded in an int.

int zero = 0x0034;

Now make an array of ints of all the chars you want to support

int BCint[40] = {....TBD ...}
char BCchar[40] = "#0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ ";

lookup the index in the BCchar and use the index to find the corresponding int in thBCint array

This brings back the whole logic to something like this...

char text[] = "HELLO";

for (int i=0; i< strlen(text); i++)
{
  c = text[i];  // optionally do a toupper();
  int index = -1;
  for (int j=0; j<40; j++)   
  {
    if (BCchar[j] == c)
    {
      index = j;
      break;
    }
  }
  if (index > -1) printCode(BCint[index]);
}

int indexof(char c, char* ar)
{
  int rv = -1;
  for

searching the character in the BCchar array can be made faster by

  • using binary search or
  • order the chars based upon - Letter frequency - Wikipedia - (the ints should be ordered accordingly)
  • use the ascii value of the char to display to calculate the index ==> isdigit() etc...

Succes

6

sth77:
My android device with the Barcode Scanner was able to scan the photo. It's the text TEST, right?

That is correct. It seems quite easy to decode.

robtillaart:

including more efficient lookup table packing

The codes can be optimized quite easily

I was able to implement your method although its easier said then done :grin:

searching the character in the BCchar array can be made faster by

  • using binary search or
  • order the chars based upon - Letter frequency - Wikipedia - (the ints should be ordered accordingly)
  • use the ascii value of the char to display to calculate the index ==> isdigit() etc...

Succes

Speed is fairly uncritical because the LCD is slow.

Here is the new code:

#include <serialGLCD.h>
#include <ctype.h>
serialGLCD lcd;
char index[]="0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ-. $/+%*";
int code[]={52,289,97,352,49,304,112,37,292,100,265,73,328,25,280,88,13,268,76,28,259,67,322,19,274,82,7,262,70,22,385,193,448,145,400,208,133,388,196,168,162,138,42,148,0};
  int xc = 1;
   void intr(int c){
    int n;
    int mask = 256;
    char state = 1;
    for(n = 0;n < 9;n++){
        if(c & mask){
          if(state){
            lcd.drawLine(xc, 0, xc, 64, 0); delay(7); lcd.drawLine(xc+1, 0, xc+1, 64, 0); delay(6);
          }          
          xc+=2; 
        } else {
          if(state){
            lcd.drawLine(xc, 0, xc, 64, 0); delay(7); 
          }
          xc++;
        }
      mask /= 2;
      state = !state;
     if(xc > 128){Serial.println("OVRFLW");}
    }
    xc++;
  }
void str(char *s){
  char a;
  int r;
  for(a = 0;a < strlen(s);a++){
    for(r = 0;r < strlen(index);r++){
      if(toupper(s[a]) == index[r]){
       intr(code[r]);
       break;
      }
    }
  }
}
void setup(){ 
  Serial.begin(115200);
  delay(1500);
  lcd.resetLCD();
  delay(250);
  unsigned char x,y;
  for(x = 0;x < 128;x++){
    for(y = 0;y < 64;y++){
      lcd.togglePixel(x, y, 1);
    }
  }
  str("*TEST*");
}
void loop(){

}
7

I wonder if 2-D barcodes would readable from an LCD?

I have to ask: other than the coolness-factor why did you do this?

8

Yes.

I have to ask: other than the coolness-factor why did you do this?

Who wouldn't want to generate a barcode with an Arduino and display it on an LCD?
Its mostly about the "coolness-factor".

Note the QR code was displayed but not generated. Generating QR codes is difficult.

Cam0Pic12-05-05_16.38.29.jpg

9

Who wouldn't want to generate a barcode with an Arduino and display it on an LCD?

And with similar code it might be printed on a thermal printer (ok other drawline routine)

Note the QR code was displayed but not generated. Generating QR codes is difficult.

For those who want to try (no arduio code) check - libqrencode -

10

Hi, i tried the above code, but i'm getting a black screen with a few white dots.
Is the code working?

11

I don't have a Serial GLCD like yours , I just have a KS0108 display. Can you help me to adapt the code with another library?