i2c.cpp

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#include <linux/i2c-dev.h>
#include <sys/ioctl.h>
#include <stdio.h>
#include <fcntl.h>
#include <arpa/inet.h>
#include <ros/ros.h>

#include "i2c.h"

int fd;

void i2c_setup(uint8_t bus, uint8_t addr)
{
        char filename[50];
        sprintf(filename, "/dev/i2c-%d", bus);

        fd = open(filename, O_RDWR);

        if (fd < 0) {
                ROS_FATAL("Failed to open I2C bus %d", bus);
                ros::shutdown();
        }

        int rc = ioctl(fd, I2C_SLAVE, addr);
        if (rc < 0) {
                ROS_FATAL("Failed to select I2C device with address 0x%02x", addr);
                ros::shutdown();
        }
}

void i2c_release()
{
        close(fd);
}

bool i2c_readRegisterMulti(uint16_t reg, size_t count, void *pdata)
{
        reg = htons(reg); // little endian to big endian

        // write register number
        if (write(fd, &reg, sizeof(reg)) < 0) {
                return false;
        }

        return read(fd, pdata, count);
}

bool i2c_readRegisterByte(int reg, uint8_t *pdata)
{
        return i2c_readRegisterMulti(reg, 1, pdata) > 0;
}

bool i2c_readRegisterWord(uint16_t reg, uint16_t *pdata)
{
        if (i2c_readRegisterMulti(reg, 2, pdata) < 0) {
                return false;
        }
        *pdata = ntohs(*pdata); // big endian to little endian
        return true;
}

bool i2c_writeRegisterMulti(uint16_t reg, size_t count, void *pdata)
{
        uint8_t buf[count + sizeof(reg)];

        reg = htons(reg); // little endian to big endian

        memcpy(buf, &reg, sizeof(reg));
        memcpy(buf + sizeof(reg), pdata, count);

        return write(fd, buf, count + sizeof(reg)) > 0;
}

bool i2c_writeRegisterByte(uint16_t reg, uint8_t value)
{
        return i2c_writeRegisterMulti(reg, 1, &value);
}


bool i2c_writeRegisterWord(uint16_t reg, uint16_t value)
{
        value = htons(value); // little endian to big endian
        return i2c_writeRegisterMulti(reg, 2, &value);
}