#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/i2c-dev.h>

float adc_read(int fd, int channel)
{
	int16_t ret16;
	uint8_t reg[3];

	reg[0] = 0x01;	//address of config register
	reg[1] = 0xc5 | (channel << 4);//OS=1,MUX=4+channel,PGA=2,MODE=1
	reg[2] = 0x43;	//DR=4,COMP_QUE=3
	if (write(fd, reg, 3) != 3) {
		printf("failed to write device.\n");
		return -1;
	}

	reg[0] = 0;
	while(1) {
		if (read(fd, reg, 2) != 2) {
			printf("failed to read device.\n");
			return -1;
		}
		if (reg[0] & 0x80) {
			break;
		}
	}

	reg[0] = 0x00;	//address of conversion register
	if (write(fd, reg, 1) != 1) {
		printf("failed to write device.\n");
		return -1;
	}

	if (read(fd, reg, 2) != 2) {
		printf("failed to read device.\n");
		return -1;
	}

	ret16 = (int16_t)reg[0] << 8 | reg[1];

	return (float)(2.048 / 32767 * 4 * ret16);
}

int main(int argc, char **argv)
{
	int i, fd_48, fd_49;
	float Ain[8];

	if ((fd_48 = open("/dev/i2c-1", O_RDWR)) < 0) {
		printf("failed to open 0x48 device.\n");
		return 1;
	}

	if (ioctl(fd_48, I2C_SLAVE, 0x48) < 0) {
		printf("failed to ioctl 0x48 device.\n");
		return 1;
	}

	if((fd_49 = open("/dev/i2c-1", O_RDWR)) < 0) {
		printf("failed to open 0x49 device.\n");
		return 1;
	}

	if(ioctl(fd_49, I2C_SLAVE, 0x49) < 0) {
		printf("failed to ioctl 0x49 device.\n");
		return 1;
	}

	for(i=0;i<4;i++) {
		Ain[i] = adc_read(fd_48, i);
	}
	for(i=0;i<4;i++) {
		Ain[i+4] = adc_read(fd_49, i);
	}
	for(i=0;i<8;i++){
		printf("channel-%d: %2.3f V\n", i, Ain[i]);
	}
	close(fd_48);
	close(fd_49);

	return 0;
}