====== Simple code pour contrôler 3 afficheurs Adafruit : HT16K3 + 7 segments en I2C sur Raspberry pi avec WiringPi ======

<code>
#include <stdio.h>
#include <unistd.h>
#include <stdint.h>
#include <wiringPi.h>
#include <wiringPiI2C.h>

#include <sys/time.h>

#include <stdbool.h>

#define HT16K33_BLINK_CMD 0x80
#define HT16K33_BLINK_DISPLAYON 0x01
#define HT16K33_BLINK_OFF 0
#define HT16K33_BLINK_2HZ  1
#define HT16K33_BLINK_1HZ  2
#define HT16K33_BLINK_HALFHZ  3

#define HT16K33_CMD_BRIGHTNESS 0xE0

#define SEVENSEG_DIGITS 5

// déclaration globale
uint16_t displaybuffer[12];

static const uint8_t numbertable[] = {
	0x3F, /* 0 */
	0x06, /* 1 */
	0x5B, /* 2 */
	0x4F, /* 3 */
	0x66, /* 4 */
	0x6D, /* 5 */
	0x7D, /* 6 */
	0x07, /* 7 */
	0x7F, /* 8 */
	0x6F, /* 9 */
	0x77, /* a */
	0x7C, /* b */
	0x39, /* C */
	0x5E, /* d */
	0x79, /* E */
	0x71, /* F */
};

void setBrightness(int fd, uint8_t b) {
  if (b > 15) b = 15;
  wiringPiI2CWrite(fd, HT16K33_CMD_BRIGHTNESS | b);
}

void blinkRate(int fd, uint8_t b) {
  if (b > 3) b = 0; // turn off if not sure
  wiringPiI2CWrite(fd, HT16K33_BLINK_CMD | HT16K33_BLINK_DISPLAYON | (b << 1));
}

void begin(int fd) {
  wiringPiI2CWrite(fd, 0x21);
  blinkRate(fd, HT16K33_BLINK_OFF);
  setBrightness(fd, 15); // max brightness
}

void writeDisplay(int fd, int offset) {
  uint8_t addr = (uint8_t) 0x00;	
  uint8_t i=0;
  for(i=0 ; i<4 ; i++) {
	if(i==2) // 2 points
	    addr+=2;  
        wiringPiI2CWriteReg8(fd, addr++, displaybuffer[i+offset] & 0xFF);
        wiringPiI2CWriteReg8(fd, addr++, displaybuffer[i+offset] >> 8); 
  } 
}

void clear(void) {
  uint8_t i=0;
  for (i=0; i<12; i++) {
    displaybuffer[i] = 0;
  }
}

void writeDigitRaw(uint8_t d, uint8_t bitmask) {
  if (d > 11) return;
  displaybuffer[d] = bitmask;
}

void writeDigitNum(uint8_t d, uint8_t num, bool dot) {
  if (d > 11) return;
  writeDigitRaw(d, numbertable[num] | (dot << 7));
}

int main()
{
	// setup
	int fda = wiringPiI2CSetup(0x70);
	int fdb = wiringPiI2CSetup(0x71);
	int fdc = wiringPiI2CSetup(0x72);
	
	printf("fda : %d \n", fda);
	printf("fdb : %d \n", fdb);
	printf("fdc : %d \n", fdc);

	// begin
	begin(fda);
	begin(fdb);
	begin(fdc);
	
	// clear
	clear();

        // loop
	int num = 0;
	while(true) {
		// write first display
		writeDigitNum(0, num, false);
		writeDigitNum(1, (num + 1) % 10, false);
		writeDigitNum(2, (num + 2) % 10, false);
		writeDigitNum(3, (num + 3) % 10, false);
		
                // write second display
		writeDigitNum(4, (num + 4) % 10, false);
		writeDigitNum(5, (num + 5) % 10, false);
		writeDigitNum(6, (num + 6) % 10, false);
		writeDigitNum(7, (num + 7) % 10, false);
		
                // write third display
		writeDigitNum(8, (num + 8) % 10, false);
		writeDigitNum(9, (num + 9) % 10, false);
		writeDigitNum(10, (num + 10) % 10, false);
		writeDigitNum(11, (num + 11) % 10, false);
			
		// write displays
		writeDisplay(fda, 0);
		writeDisplay(fdb, 4);
		writeDisplay(fdc, 8);
		
		// sleep
		sleep(1); // second
		
		// increment
		num++;
		num %= 10; 
	}
	return 1;
}

</code>