8x8 LED Matrix - I2C Communication - Red

Led Matrix 8x8 with 3mm pitch between the LED's that can be controlled via I2C.

Specifications:

• Supply voltage: 4.5 - 5.5V DC
• Signal voltage: 4.5 - 5.5V
• Chipset: HT16K33
• I2C communication
• Default I2C address: 0x70 (adjustable between 0x70-0x77 with the A0-A1 solder points)
• Connector: 4p JST-XH 
• LED color: Red
• Pinout:
  • G: Ground (-)
  • V: Power (5V)
  • D: SDA
  • C: SCL
• Dimensions: 32x32mm

Package contents:

• 1x 8x8 LED Matrix with HT16K33 chip

Note: JST-XH cable is not included, but can be bought seperately: JST-XH Connector with cable - 4 Pins.

Instructions for Arduino:

1. Install the "Adafruit LED Backpack Library" via the Library Manager in the Arduino IDE.
2. Go to C:\Users\*Windows gebruiker*\Documents\Arduino\libraries\Adafruit_LED_Backpack_Library (or the other location where the libary is installed).
3. Open the Adafruit_LEDBackpack.cpp file.
4. Go to line 226 (function "void Adafruit_LEDBackpack::writeDisplay(void)").
5. Add this function before the function "void Adafruit_LEDBackpack::writeDisplay(void)":

   void Adafruit_LEDBackpack::writeDisplayCustom(void) {
     Wire.beginTransmission(i2c_addr);
     Wire.write((uint8_t) 0x00); // start at address $00
   
     // Create a copy of the buffer
     uint16_t displaybuffertemp[8];
     memcpy(displaybuffertemp, displaybuffer, sizeof(displaybuffertemp));
   
     // Shift data to correct row
     for (uint8_t i = 0; i < 8; i++) {
       uint8_t tempbuffer3 = displaybuffertemp[i] & 0xFF;
       displaybuffertemp[i] &= 0xFF00;
       displaybuffertemp[i] |= (tempbuffer3 << 1) | (tempbuffer3 >> 7);
     }
   
     // Shift data to correct row
     uint16_t tempbuffer2 = displaybuffertemp[3];
     displaybuffertemp[3] = displaybuffertemp[5];
     displaybuffertemp[5] = tempbuffer2;
   
     // Mirror data
     for (uint8_t i = 0; i < 8; i++) {
       uint8_t tempbuffer = displaybuffertemp[i] & 0xFF;
       displaybuffertemp[i] &= 0xFF00;
       for (uint8_t k = 0; k < 8; k++) {
         if (tempbuffer & (0x01 << k)) {
           displaybuffertemp[i] |= 0x01 << (7 - k);
         }
       }
     }
   
     // Send buffer to display
     for (uint8_t i = 0; i < 8; i++) {
       Wire.write(displaybuffertemp[i] & 0xFF);
       Wire.write(displaybuffertemp[i] >> 8);
     }
     Wire.endTransmission();
   }
       

6. Open the Adafruit_LEDBackpack.h file.
7. Go to line 90 (function "void writeDisplay(void);").
8. Add this function before the function "void writeDisplay(void);":

         void writeDisplayCustom(void);
       

9. Use the function "writeDisplayCustom" instead of "writeDisplay" in all parts of the Arduino code.