i2cps.c

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/******************************************************************************
 *
 *
 * @file i2cps.c
 *
 * Functions to interact with linux I2C. No safe checks here, so users must
 * know what they are doing.
 *
 * <pre>
 * MODIFICATION HISTORY:
 *
 * Ver   Who  Date     Changes
 * ----- --- ------- -----------------------------------------------
 * 1.00a gn  02/03/16 release
 * 1.00b yrq 08/31/16 add license header
 *
 * </pre>
 *
 *****************************************************************************/
 
#include "i2cps.h"
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <unistd.h>
 
int setI2C(unsigned int index, long slave_addr) {
  int i2c_fd;
  char buf[50];
  sprintf(buf, "/dev/i2c-%d", index);
  // printf("buf = %s \n",buf);
  if ((i2c_fd = open(buf, O_RDWR)) < 0) {
    return -1;
  }
  if (ioctl(i2c_fd, I2C_SLAVE, slave_addr) < 0) {
    return -1;
  }
  return i2c_fd;
}
 
int unsetI2C(int i2c_fd) {
  close(i2c_fd);
  return 0;
}
 
int writeI2C_asFile(int i2c_fd, unsigned char writebuffer[],
                    unsigned char bytes) {
  unsigned char bytesWritten = write(i2c_fd, writebuffer, bytes);
  if (bytes != bytesWritten) {
    return -1;
  }
  return 0;
}
 
int readI2C_asFile(int i2c_fd, unsigned char readbuffer[],
                   unsigned char bytes) {
  unsigned char bytesRead = read(i2c_fd, readbuffer, bytes);
  if (bytes != bytesRead)
    return -1;
  return 0;
}