lm75.c

LM75温度侦测芯片

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <termios.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <linux/ioctl.h>
#include <linux/i2c-dev.h>
#include <asm/errno.h>

#include "lm75.h"

#define I2C_SLAVE 0x0703
#define ID_PHY 0x96


/* The LM75 registers */
#define LM75_REG_TEMP       0x00
#define LM75_REG_CONF       0x01
#define LM75_REG_TEMP_HYST  0x02
#define LM75_REG_TEMP_OS    0x03

/* Each client has this additional data */
struct lm75_data {
    unsigned short	temp_input; /* Register values */
    unsigned short	temp_max;
    unsigned short	temp_hyst;
};
static int lm75_init(int file);
static int lm75_get_temp(int file, struct lm75_data * value);
main(int argc, char **argv)
{
	int file;
  	int adapter_nr = 0;
  	char filename[20];
	struct lm75_data value;
	int  ret;

  	sprintf(filename, "/dev/i2c-%d", adapter_nr);
  	if ((file = open(filename, O_RDWR)) < 0) {
		perror("No such i2c device!\n");
  	  	exit(1);
  	}
	
	int addr = (ID_PHY) >> 1; /* The I2C address */
	if ((ret = ioctl(file, I2C_SLAVE, addr)) < 0) {
		if(ret ==  -EBUSY)
			printf("Device busy\n");
		if(ret == -EINVAL)
			printf("invalid addr\n");
		printf("No such slave device. %d\n ", ret);
		close(file);
   		exit(1);
  	}
	
	lm75_init(file);
	
	lm75_get_temp(file, &value);		

	printf("temp_input: %d , temp_max: %d , temp_hyst: %d \n", 
				LM75_TEMP_FROM_REG(value.temp_input), 
				LM75_TEMP_FROM_REG(value.temp_max), 
				LM75_TEMP_FROM_REG(value.temp_hyst) );

	close(file);
}

static int 
lm75_init(int file)
{	
	unsigned char buf[2];

	memset(buf, 0, sizeof(buf));
	buf[0] = LM75_REG_CONF;
	write(file, buf , 1);
	buf[0] = 0;
	write(file, buf , 1);	
}

static int 
lm75_get_temp(int file, struct lm75_data * value)
{
    int ret = -EIO;
    unsigned char buf[5];
    int i; 

    memset(buf, 0, sizeof(buf));
	buf[0] = LM75_REG_TEMP;
while(1){
	write(file, buf , 1);
sleep(1);
}
    ret = read(file, buf, 2);
    if (ret<0){
       	perror("read error!\n");
		exit(1);
	}
    value->temp_input = (unsigned short)buf[0]<<8 | buf[1];

	buf[0] = LM75_REG_TEMP_OS;
	write(file, buf , 1);
    ret = read(file, buf, 2);
    if (ret<0){
       	perror("read error!\n");
		exit(1);
	}
    value->temp_max = (unsigned short)buf[0]<<8 | buf[1];

	buf[0] = LM75_REG_TEMP_HYST;
	write(file, buf , 1);
    ret = read(file, buf, 2);
    if (ret<0){
       	perror("read error!\n");
		exit(1);
	}
    value->temp_hyst = (unsigned short)buf[1]<<8 | buf[0];

    return 0;
}