QR Code generation with 3.5" TFT Touch screen on Arudino MEGA2560

Synopis

Displays a QR Code on the LCD screen

Notes

This will display a Version 1 QR code. The scaling and centering features are incomplete, but the overall code is functional in this precise instance.

QR Code library used

LCDWIKI Libraries

Code

 1 #define GUARD 8 //number of guard blocks to create around QR code
 2 #define QR_VERSION 3  //Version of the QR Code
 3 #define ECC 0 //Error correction level
 4 #define SAFE_MIN 1 //Smallest module size before warning is issued
 5 
 6 #include "qrcode.h"
 7 #include <LCDWIKI_GUI.h> //Core graphics library
 8 #include <LCDWIKI_KBV.h> //Hardware-specific library
 9 
10 const int spiCSPin = 53;
11 LCDWIKI_KBV mylcd(ILI9486,A3,A2,A1,A0,A4); //model,cs,cd,wr,rd,reset
12 
13 
14 void setup() {
15     int height = mylcd.Get_Display_Height(); //Formerly 'l' 
16     int width = mylcd.Get_Display_Width(); //Formerly 'w'
17     int module_size; //Formerly 'm'
18     int width_offset; //Formerly xo, yo
19     int height_offset;
20     int width_center;
21     int height_center;
22     
23     Serial.begin(115200);
24     mylcd.Init_LCD();
25     mylcd.Fill_Screen(0xFFFF);
26     delay(2000);
27     mylcd.Set_Draw_color(0x0000);
28 
29     // Create the QR code
30     QRCode qrcode;
31     uint8_t qrcodeData[qrcode_getBufferSize(QR_VERSION)];
32     qrcode_initText(&qrcode, qrcodeData, QR_VERSION, ECC, "Arduino");
33 
34     //which dimension constrains the QR code dimensions?
35     //Calculate the maximum length of the module size in pixels
36     //Integer division always truncates to a safe lower value.
37     if(height<width)
38       module_size=height/(qrcode.size+2*GUARD);
39     else
40       module_size=width/(qrcode.size+2*GUARD);
41     if(module_size<SAFE_MIN)
42       Serial.println("Warning: QR Code may be difficult or impossible to scan given display resolution.");
43     height_center = (height - module_size*(qrcode.size+2*GUARD))/2;
44     width_center  = (width  - module_size*(qrcode.size+2*GUARD))/2;
45     
46     Serial.print("Each module is ");
47     Serial.print(module_size);
48     Serial.println(" pixels wide.");
49     Serial.print("QR Size is ");
50     Serial.print(qrcode.size);
51     Serial.println(".");
52 
53     // Each vertical module
54     for (uint8_t y = 0; y < qrcode.size; y++)
55     {
56         // Each horizontal module
57         for (uint8_t x = 0; x < qrcode.size; x++)
58         {
59             if(qrcode_getModule(&qrcode, x, y))
60             {
61               width_offset  = width_center  + module_size*GUARD + module_size*x;
62               height_offset = height_center + module_size*GUARD + module_size*y;
63               for(int i=0;i<module_size;i++)
64               {
65                 for(int j=0;j<module_size;j++)
66                 {
67                   mylcd.Draw_Pixel(width_offset+i,height_offset+j);
68                 }
69               }
70             }
71         }
72     }
73 }
74 
75 void loop() {
76 
77 }