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i2c [2016/01/10 21:25] – created bullari2c [2016/01/10 21:31] (current) – external edit 127.0.0.1
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 </code> </code>
  
 +Example program (part of retest)
  
 +<file c i2c.h>
 +/*
 + * i2c.h
 + *
 + *  Created on: Jan 3, 2016
 + *      Author: rcar
 + */
  
 +#ifndef I2C_H_
 +#define I2C_H_
 +
 +#include <stdint.h>
 +
 +void i2cOpen(uint8_t devno);
 +void i2cClose();
 +void i2cSetAddress(uint8_t address);
 +uint8_t i2cReadData8(uint8_t reg);
 +int16_t i2cReadData16(uint8_t reg);
 +void i2cWriteData8(uint8_t reg, uint8_t value);
 +void i2cWriteData16(uint8_t reg, uint16_t value);
 +void i2cDetectDevice(void);
 +void i2cReadRCValues(void);
 +
 +#endif /* I2C_H_ */
 +</file>
 +
 +
 +<file c i2c.c>
 +/*
 + * i2c.c
 + *
 + *  Created on: Jan 3, 2016
 + *      Author: rcar
 + */
 +
 +#include <stdint.h>
 +#include <stdlib.h>
 +#include <stdio.h>
 +#include <string.h>
 +#include <unistd.h>
 +#include <linux/i2c-dev.h>
 +#include <sys/types.h>
 +#include <sys/stat.h>
 +#include <sys/ioctl.h>
 +#include <fcntl.h>
 +
 +#include "i2c.h"
 +#include "mpu.h"
 +
 +// I2C Linux device handle
 +int g_i2cFile;
 +
 +//------------------------------------------------------------------------
 +// open the Linux device
 +void i2cOpen(uint8_t devno)
 +{
 + char device[20];
 + snprintf(device, sizeof device, "/dev/i2c-%d", devno);
 + g_i2cFile = open(device, O_RDWR);
 + if (g_i2cFile < 0) {
 + perror("i2cOpen");
 + exit(1);
 + }
 +}
 +
 +//------------------------------------------------------------------------
 +// close the Linux device
 +void i2cClose()
 +{
 + close(g_i2cFile);
 +}
 +
 +//------------------------------------------------------------------------
 +// set the I2C slave address for all subsequent I2C device transfers
 +void i2cSetAddress(uint8_t address)
 +{
 + if (ioctl(g_i2cFile, I2C_SLAVE, address) < 0) {
 + perror("i2cSetAddress");
 + exit(1);
 + }
 +}
 +
 +//------------------------------------------------------------------------
 +// read 8-bit value from register reg
 +uint8_t i2cReadData8(uint8_t reg) {
 +
 + uint8_t  data;
 +
 + if (write(g_i2cFile, &reg, 1) != 1) {
 + perror("i2cReadData8 set register");
 + return 0;
 + }
 + if (read(g_i2cFile, &data, 1) != 1) {
 + perror("i2cReadData8 read value");
 + return 0;
 + }
 + return data;
 +}
 +
 +//------------------------------------------------------------------------
 +// read a 16 bit value from a register pair
 +// read high byte of value from register reg,
 +// and low byte of value from register reg+1
 +int16_t i2cReadData16(uint8_t reg) {
 +
 + uint8_t  data[2];
 +
 + if (write(g_i2cFile, &reg, 1) != 1) {
 + perror("i2cReadData8 set register");
 + return 0;
 + }
 + if (read(g_i2cFile, data, 2) != 2) {
 + perror("i2cReadData8 read value");
 + return 0;
 + }
 + return data[1] | (data[0] << 8);
 +}
 +
 +//------------------------------------------------------------------------
 +// write a 8 bit value to a register reg
 +void i2cWriteData8(uint8_t reg, uint8_t value)
 +{
 + uint8_t data[2];
 + data[0] = reg;
 + data[1] = value;
 + if (write(g_i2cFile, data, 2) != 2) {
 + perror("i2cWriteData8");
 + }
 +}
 +
 +//------------------------------------------------------------------------
 +// write a 16 bit value to a register pair
 +// write high byte of value to register reg,
 +// and low byte of value to register reg+1
 +void i2cWriteData16(uint8_t reg, uint16_t value)
 +{
 + uint8_t data[3];
 + data[0] = reg;
 + data[1] = (value >> 8) & 0xff;
 + data[2] = value & 0xff;
 + if (write(g_i2cFile, data, 3) != 3) {
 + perror("i2cWriteData16");
 + }
 +}
 +
 +//------------------------------------------------------------------------
 +// try to detect both i2c devices
 +// MPU-6050 has a fixed ID of 0x68 at reg 0x75
 +// RC-Mixer has a fixed ID of 0x34 at reg 0x1F
 +void i2cDetectDevice(void) {
 +
 + uint16_t result;
 +
 + // MPU-6050
 + i2cOpen(2); // is at i2c-2
 + i2cSetAddress(MPU6050_ADDRESS); // address of MPU-6050
 + result = i2cReadData8(MPU6050_RA_WHO_AM_I);
 + printf("Check Addr:0x68 Reg:0x75 Data:%x", result);
 + if (result == 0x68) printf("  => MPU-6050 found!\n");
 + else printf("  => MPU-6050 missing!\n");
 + i2cClose();
 +
 + // RC-Mixer
 + i2cOpen(1); // is at i2c-1
 + i2cSetAddress(0x34); // address of RC-Mixer
 + result = i2cReadData8(31);
 + printf("check Addr:0x34 Reg:0x1F Data:%x", result);
 + if (result == 0x34) printf("  => RC-Mixer found!\n");
 + else printf("  => RC-Mixer missing!\n");
 + i2cClose();
 +}
 +
 +//------------------------------------------------------------------------
 +// get RC values from RC-Mixer
 +void i2cReadRCValues(void) {
 +
 + uint16_t result;
 + int i;
 +
 + // RC-Mixer
 + i2cOpen(1); // is at i2c-1
 + i2cSetAddress(0x34); // address of RC-Mixer
 +
 + printf("RC value from RC-Mixer\n");
 + printf("CH1   CH2   CH3   CH4   CH5   PWM3  PWM4  STEER MOTOR\n");
 + for(i=0;i<9;i++) {
 + result = i2cReadData16(i*2);
 + printf("%04d  ",result);
 + }
 + printf("\n");
 + i2cClose();
 +}
 +</file>
i2c.1452461136.txt.gz · Last modified: 2016/01/10 21:25 by bullar

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