PX4-Autopilot/src/drivers/pca9685_pwm_out/PCA9685.cpp

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#include <px4_log.h>
#include <cmath>
#include "PCA9685.h"

using namespace drv_pca9685_pwm;

PCA9685::PCA9685(int bus, int addr):
	I2C(DRV_PWM_DEVTYPE_PCA9685, MODULE_NAME, bus, addr, 400000)
{

}

int PCA9685::Stop()
{
	disableAllOutput();
	stopOscillator();
	return PX4_OK;
}

int PCA9685::updatePWM(const uint16_t *outputs, unsigned num_outputs)
{
	if (num_outputs > PCA9685_PWM_CHANNEL_COUNT) {
		num_outputs = PCA9685_PWM_CHANNEL_COUNT;
		PX4_DEBUG("PCA9685 can only drive up to 16 channels");
	}

	uint16_t out[PCA9685_PWM_CHANNEL_COUNT];
	memcpy(out, outputs, sizeof(uint16_t) * num_outputs);

	for (unsigned i = 0; i < num_outputs; ++i) {
		out[i] = (uint16_t)roundl((out[i] * _Freq * PCA9685_PWM_RES / (float)1e6)); // convert us to 12 bit resolution
	}

	setPWM(num_outputs, out);

	return 0;
}

int PCA9685::setFreq(float freq)
{
	uint16_t realResolution = floorl((float)PCA9685_CLOCK_FREQ / freq);

	if (realResolution < PCA9685_PWM_RES) { // unable to provide enough resolution
		PX4_DEBUG("frequency too high");
		return -EINVAL;
	}

	uint16_t divider = (uint16_t)round((float)PCA9685_CLOCK_FREQ / freq / PCA9685_PWM_RES) - 1;

	if (divider > 0x00FF) { // out of divider
		PX4_DEBUG("frequency too low");
		return -EINVAL;
	}

	float freq_err = ((float)PCA9685_CLOCK_FREQ / (float)(divider + (uint16_t)1)
			  - (float)(freq * PCA9685_PWM_RES))
			 / (float)(freq * PCA9685_PWM_RES); // actually asked for (freq * PCA9685_PWM_RES)

	if (fabsf(freq_err) > 0.01f) { // TODO decide threshold
		PX4_WARN("frequency error too large: %.4f", (double)freq_err);
		// should we return an error?
	}

	_Freq = (float)PCA9685_CLOCK_FREQ / (float)(divider + (uint16_t)1) / PCA9685_PWM_RES; // use actual pwm freq instead.

	setDivider(divider);

	return PX4_OK;

}

int PCA9685::initReg()
{
	uint8_t buf[2] = {};

	buf[0] = PCA9685_REG_MODE1;
	buf[1] = DEFAULT_MODE1_CFG;
	int ret = transfer(buf, 2, nullptr, 0); // make sure oscillator is disabled

	if (OK != ret) {
		PX4_ERR("init: i2c::transfer returned %d", ret);
		return ret;
	}

	ret = transfer(buf, 2, nullptr, 0); // enable EXTCLK if possible

	if (OK != ret) {
		PX4_ERR("init: i2c::transfer returned %d", ret);
		return ret;
	}

	buf[0] = PCA9685_REG_MODE2;
	buf[1] = DEFAULT_MODE2_CFG;
	ret = transfer(buf, 2, nullptr, 0);

	if (OK != ret) {
		PX4_ERR("init: i2c::transfer returned %d", ret);
		return ret;
	}

	return PX4_OK;
}

int PCA9685::probe()
{
	return I2C::probe();
}

void PCA9685::setPWM(uint8_t channel, const uint16_t &value)
{
	if (value >= 4096) {
		PX4_DEBUG("invalid pwm value");
		return;
	}

	uint8_t buf[5] = {};
	buf[0] = PCA9685_REG_LED0 + channel * PCA9685_REG_LED_INCREMENT;
	buf[1] = 0x00;
	buf[2] = 0x00;
	buf[3] = (uint8_t)(value & (uint8_t)0xFF);
	buf[4] = value != 0 ? ((uint8_t)(value >> (uint8_t)8)) : PCA9685_LED_ON_FULL_ON_OFF_MASK;

	int ret = transfer(buf, 5, nullptr, 0);

	if (OK != ret) {
		PX4_DEBUG("setPWM: i2c::transfer returned %d", ret);
	}
}

void PCA9685::setPWM(uint8_t channel_count, const uint16_t *value)
{
	uint8_t buf[PCA9685_PWM_CHANNEL_COUNT * PCA9685_REG_LED_INCREMENT + 1] = {};
	buf[0] = PCA9685_REG_LED0;

	for (int i = 0; i < channel_count; ++i) {
		if (value[i] >= 4096) {
			PX4_DEBUG("invalid pwm value");
			return;
		}

		buf[1 + i * PCA9685_REG_LED_INCREMENT] = 0x00;
		buf[2 + i * PCA9685_REG_LED_INCREMENT] = 0x00;
		buf[3 + i * PCA9685_REG_LED_INCREMENT] = (uint8_t)(value[i] & (uint8_t)0xFF);
		buf[4 + i * PCA9685_REG_LED_INCREMENT] = value[i] != 0 ? ((uint8_t)(value[i] >> (uint8_t)8)) :
				PCA9685_LED_ON_FULL_ON_OFF_MASK;
	}

	int ret = transfer(buf, channel_count * PCA9685_REG_LED_INCREMENT + 1, nullptr, 0);

	if (OK != ret) {
		PX4_DEBUG("setPWM: i2c::transfer returned %d", ret);
	}
}

void PCA9685::disableAllOutput()
{
	uint8_t buf[5] = {};
	buf[0] = PCA9685_REG_ALLLED_ON_L;
	buf[1] = 0x00;
	buf[2] = 0x00;
	buf[3] = 0x00;
	buf[4] = PCA9685_LED_ON_FULL_ON_OFF_MASK;

	int ret = transfer(buf, 5, nullptr, 0);

	if (OK != ret) {
		PX4_DEBUG("i2c::transfer returned %d", ret);
	}
}

void PCA9685::setDivider(uint8_t value)
{
	uint8_t buf[2] = {};
	buf[0] = PCA9685_REG_PRE_SCALE;
	buf[1] = value;
	int ret = transfer(buf, 2, nullptr, 0);

	if (OK != ret) {
		PX4_DEBUG("i2c::transfer returned %d", ret);
		return;
	}
}

void PCA9685::stopOscillator()
{
	uint8_t buf[2] = {PCA9685_REG_MODE1};

	// set to sleep
	buf[1] = DEFAULT_MODE1_CFG;
	int ret = transfer(buf, 2, nullptr, 0);

	if (OK != ret) {
		PX4_DEBUG("i2c::transfer returned %d", ret);
		return;
	}
}

void PCA9685::startOscillator()
{
	uint8_t buf[2] = {PCA9685_REG_MODE1};

	// clear sleep bit, with restart bit = 0
	buf[1] = DEFAULT_MODE1_CFG & (~PCA9685_MODE1_SLEEP_MASK);
	int ret = transfer(buf, 2, nullptr, 0);

	if (OK != ret) {
		PX4_DEBUG("startOscillator: i2c::transfer returned %d", ret);
		return;
	}
}

void PCA9685::triggerRestart()
{
	uint8_t buf[2] = {PCA9685_REG_MODE1};

	// clear sleep bit, with restart bit = 0
	buf[1] = DEFAULT_MODE1_CFG & (~PCA9685_MODE1_SLEEP_MASK);
	buf[1] |= PCA9685_MODE1_RESTART_MASK;
	int ret = transfer(buf, 2, nullptr, 0);

	if (OK != ret) {
		PX4_DEBUG("triggerRestart: i2c::transfer returned %d", ret);
		return;
	}
}