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====== HT16K33 LED Module - Low Dependency Example ======

This works from an Arduino, talking to the HT16K33. It needs to be moved to a Raspberry Pi, because it is hard to have two Masters.

<code c++>
#include <Wire.h>
 
const uint8_t addr = 0x70; // HT16K33 default address
uint16_t displayBuffer[8];
 
void setup() {
  Wire.begin();
 
  Wire.beginTransmission(addr);
  Wire.write(0x20 | 1); // turn on oscillator
  Wire.endTransmission();
 
  setBrightness(15);
  blink(0);
}
 
void loop() {
  const int dTime = 50;
 
  // Loop through all segments
  for(int i = 0; i < 8; i++){
    for(int k = 0; k < 16; k++){
      displayBuffer[i] = 1 << k;
      show();
      delay(dTime);
    }
    clear();
  }
 
  // Turn on all segments, one at a time
  for(int i = 0; i < 8; i++){
    for(int k = 0; k < 16; k++){
      displayBuffer[i] |= 1 << k;
      show();
      delay(dTime);
    }
  }
 
  // Test blinking
  for(int i = 3 ; i > 0; i--){
    blink(i);
    delay(2000);
  }
  blink(0); // Turn blinking off
 
  // Test blanking
  for(int i = 0; i < 10; i++){
    blank();
    delay(dTime * 2);
  }
 
  // Test dimming
  for(int i = 15; i >= 0; i--){
    setBrightness(i);
    delay(dTime * 2);
  }
  clear();
 
  setBrightness(15);
}
 
void show(){
  Wire.beginTransmission(addr);
  Wire.write(0x00); // start at address 0x0
 
  for (int i = 0; i < 8; i++) {
    Wire.write(displayBuffer[i] & 0xFF);    
    Wire.write(displayBuffer[i] >> 8);    
  }
  Wire.endTransmission();  
}
 
void clear(){
  for(int i = 0; i < 8; i++){
    displayBuffer[i] = 0;
  }
}
 
void setBrightness(uint8_t b){
  if(b > 15) return;
 
  Wire.beginTransmission(addr);
  Wire.write(0xE0 | b); // Dimming command
  Wire.endTransmission();
}
 
void blank(){
  static boolean blankOn;  
 
  Wire.beginTransmission(addr);
  Wire.write(0x80 | blankOn); // Blanking / blinking command
  Wire.endTransmission();
 
  blankOn = !blankOn;
}
 
void blink(uint8_t b){
  if(b > 3) return;
 
  Wire.beginTransmission(addr);
  Wire.write(0x80 | b << 1 | 1); // Blinking / blanking command
  Wire.endTransmission();
}
</code>
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