/*
 *  ms5607.c
 *
 *  Copyright (C) 2012 Computex Co.,Ltd.
 *
 *  Sample to test MS5607 using CM-3G CHECK BOARD
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <linux/i2c-dev.h>

#define I2C_DEVICE		"/dev/i2c-3"
#define DEV_ADDRESS		0x76

#define CMD_RESET		0x1E	// ADC reset command
#define CMD_ADC_READ	0x00	// ADC read command
#define CMD_ADC_CONV	0x40	// ADC conversion command
#define CMD_ADC_D1		0x00	// ADC D1 conversion
#define CMD_ADC_D2		0x10	// ADC D2 conversion
#define CMD_ADC_256		0x00	// ADC OSR=256
#define CMD_ADC_512		0x02	// ADC OSR=512
#define CMD_ADC_1024	0x04	// ADC OSR=1024
#define CMD_ADC_2048	0x06	// ADC OSR=2048
#define CMD_ADC_4096	0x08	// ADC OSR=4096
#define CMD_PROM_RD		0xA0	// Prom read command

int file;
void usage(char *app_name)
{
	printf("%s - Displays Temperature and Pressure values using MS5607 sensor\n", app_name);
	printf("Usage: %s -d [device path]\n", app_name);
	printf("\t\t-d - i2c device path (Default: "I2C_DEVICE")\n");
	printf("Eg: %s\n", app_name);
	exit(0);
}

int i2c_send(unsigned char cmd)
{
	unsigned char buf[1];
	buf[0] = cmd;
	if (write(file, buf, 1) != 1) {
		printf("Failed to write to i2c bus. Check if MS5607 is connected\n");
		return 1;
	}
	return 0;
}

int i2c_recv(unsigned char *buf, int count)
{
	if (read(file, buf, 2) != 2) {
		printf("Failed to read from to i2c bus. Check if MS5607 is connected\n");
		return 1;
	}
	return 0;
}

/*******************************************************
	Performs ADC conversion
********************************************************/
int read_adc(char cmd, unsigned int *val)
{
	unsigned char buf[3];
	/* send conversion command */
	if(i2c_send(CMD_ADC_CONV | cmd)){
		return 1;
	}
	/* wait for conversion */
	switch (cmd & 0x0f)
	{
	case CMD_ADC_256:
		usleep(900000);
		break;
	case CMD_ADC_512:
		usleep(3000);
		break;
	case CMD_ADC_1024:
		usleep(4000);
		break;
	case CMD_ADC_2048:
		usleep(6000);
		break;
	case CMD_ADC_4096:
		usleep(10000);
		break;
	}

	/* send read comand and read */
	if(i2c_send(CMD_ADC_READ)){
		return 1;
	}
	if(i2c_recv(buf, 3)){
		return 1;
	}
	*val = (buf[0]<<16) | (buf[1]<<8) | buf[2];
	return 0;
}

/*******************************************************
	Reads calibration coefficients
********************************************************/
int get_coeff(unsigned int coeff_num, double *val)
{
	unsigned char buf[2];
	/* send PROM READ command and read */
	if(i2c_send(CMD_PROM_RD + coeff_num * 2))
		return 1;
	if(i2c_recv(buf, 2)){
		return 1;
	}
	*val = (buf[0]<<8) | buf[1];
	return 0;
}

/****************************************************************
 * Main
 ****************************************************************/
int main(int argc, char* argv[])
{
	unsigned char buf[10];
	int d;
	int i;
	char shortoptions[] = "d:h";
	char input_device[16];
	float hres, hres2, lres;
	double coeff[8];
	unsigned int D1, D2;
	double dT, T, P, OFF, SENS;
	input_device[0] = 0;
	for (;;) {
		d = getopt_long(argc, argv, shortoptions, (void *)NULL, &index);
		if (-1 == d)
		{
			break;
		}
		switch (d) {
		case 'd':
			strcpy(input_device, optarg);
			break;
		default:
			usage(argv[0]);
		}
	}
	if(input_device[0] == 0)
		strcpy(input_device, I2C_DEVICE);

	file = open(input_device, O_RDWR);
	if(file < 0) {
		printf("Error: "I2C_DEVICE " open failed\n");
		exit(1);
	}
	
	if(ioctl(file, I2C_SLAVE, DEV_ADDRESS) < 0) {
		printf("Error: %s setting device address to 0x%xfailed\n", input_device, DEV_ADDRESS);
		goto _out;
	}

	/* send reset sequence */
	if (i2c_send(CMD_RESET)){
		goto _out;
	}
	
	/* wait for the reset sequence timing */
	usleep(3000);
	
	/* read coefficients */
	for(i=1; i<7; i++)
		if(get_coeff(i, &coeff[i]))
			goto _out;

	printf("Temperature     Pressure\n");
	while(1)
	{
		if(read_adc(CMD_ADC_D1 | CMD_ADC_4096, &D1)
			|| read_adc(CMD_ADC_D2 | CMD_ADC_4096, &D2))
			goto _out;
		dT = D2 - coeff[5] * 256;
		OFF = coeff[2] * 131072 + ((coeff[4] * dT) / 64);
		SENS = coeff[1] * 65536 + (coeff[3] * dT) / 128;
		T = (2000 + (dT * coeff[6]) / 8388608) / 100;
		P = (((D1 * SENS) / 2097152 - OFF) / 32768) /100; 
		printf("%0.3f℃        %0.3f mbar\n", T, P);
		sleep(1);
	}
	
_out:
	close(file);
	return 0;
}