PCA9685.cpp

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/****************************************************************************
 *
 *   Copyright (c) 2017 PX4 Development Team. All rights reserved.
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 *    distribution.
 * 3. Neither the name PX4 nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
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 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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 *
 * Original Author      : Georgi Todorov
 * Edited by    : Tord Wessman
 * Created on  : Nov 22, 2013
 * Rewrite     : Fan.zhang  421395590@qq.com
 * Updated on  : Mar 2, 2017
 ****************************************************************************/

#include <sys/stat.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <linux/i2c-dev.h>
#include <stdio.h>      /* Standard I/O functions */
#include <fcntl.h>
#include <inttypes.h>
#include <errno.h>
#include <math.h>
#include <stdio.h>
#include <unistd.h>

#include "PCA9685.h"

#include <px4_platform_common/log.h>

using namespace linux_pwm_out;

int PCA9685::init(int bus, int address)
{
    _fd = open_fd(bus, address);
    reset();

    usleep(1000 * 100);
    /* 12BIT 精度输出下，好赢电调可以到200HZ刷新 */
    /* 200HZ for 12bit Resolution, supported by most of the esc's */
    setPWMFreq(200);
    usleep(1000 * 1000);
    return 0;
}

int PCA9685::send_output_pwm(const uint16_t *pwm, int num_outputs)
{
    if (num_outputs > 16) {
        num_outputs = 16;
    }

    for (int i = 0; i < num_outputs; ++i) {
        setPWM(i, pwm[i]);
    }

    return 0;
}

PCA9685::PCA9685()
{
    init(PCA9685_DEFAULT_I2C_BUS, PCA9685_DEFAULT_I2C_ADDR);
}

PCA9685::PCA9685(int bus, int address)
{
    init(bus, address);
}

PCA9685::~PCA9685()
{
    reset();

    if (_fd >= 0) {
        close(_fd);
    }
}

void PCA9685::reset()
{
    if (_fd != -1) {
        write_byte(_fd, MODE1, 0x00); //Normal mode
        write_byte(_fd, MODE2, 0x04); //Normal mode
    }
}

void PCA9685::setPWMFreq(int freq)
{
    if (_fd != -1) {
        uint8_t prescale = (CLOCK_FREQ / MAX_PWM_RES / freq)  - 1;
        //printf ("Setting prescale value to: %d\n", prescale);
        //printf ("Using Frequency: %d\n", freq);

        uint8_t oldmode = read_byte(_fd, MODE1);
        uint8_t newmode = (oldmode & 0x7F) | 0x10;    //sleep
        write_byte(_fd, MODE1, newmode);        // go to sleep
        write_byte(_fd, PRE_SCALE, prescale);
        write_byte(_fd, MODE1, oldmode);
        usleep(10 * 1000);
        write_byte(_fd, MODE1, oldmode | 0x80);
    }
}


void PCA9685::setPWM(uint8_t led, int value)
{
    setPWM(led, 0, value);
}

void PCA9685::setPWM(uint8_t led, int on_value, int off_value)
{
    if (_fd != -1) {
        write_byte(_fd, LED0_ON_L + LED_MULTIPLYER * led, on_value & 0xFF);

        write_byte(_fd, LED0_ON_H + LED_MULTIPLYER * led, on_value >> 8);

        write_byte(_fd, LED0_OFF_L + LED_MULTIPLYER * led, off_value & 0xFF);

        write_byte(_fd, LED0_OFF_H + LED_MULTIPLYER * led, off_value >> 8);
    }

}

uint8_t PCA9685::read_byte(int fd, uint8_t address)
{

    uint8_t buf[1];
    buf[0] = address;

    if (write(fd, buf, 1) != 1) {
        return -1;
    }

    if (read(fd, buf, 1) != 1) {
        return -1;
    }

    return buf[0];
}

void PCA9685::write_byte(int fd, uint8_t address, uint8_t data)
{
    uint8_t buf[2];
    buf[0] = address;
    buf[1] = data;

    if (write(fd, buf, sizeof(buf)) != sizeof(buf)) {
        PX4_ERR("Write failed (%i)", errno);
    }
}

int PCA9685::open_fd(int bus, int address)
{
    int fd;
    char bus_file[64];
    snprintf(bus_file, sizeof(bus_file), "/dev/i2c-%d", bus);

    if ((fd = open(bus_file, O_RDWR)) < 0) {
        PX4_ERR("Couldn't open I2C Bus %d [open_fd():open %d]", bus, errno);
        return -1;
    }

    if (ioctl(fd, I2C_SLAVE, address) < 0) {
        PX4_ERR("I2C slave %d failed [open_fd():ioctl %d]", address, errno);
        return -1;
    }

    return fd;
}