PX4-Autopilot/src/drivers/barometer/ms5611/ms5611.cpp

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/**
 * @file ms5611.cpp
 * Driver for the MS5611 and MS5607 barometric pressure sensor connected via I2C or SPI.
 */

#include "MS5611.hpp"
#include "ms5611.h"

#include <cdev/CDev.hpp>

MS5611::MS5611(device::Device *interface, ms5611::prom_u &prom_buf, enum MS56XX_DEVICE_TYPES device_type,
	       I2CSPIBusOption bus_option, int bus) :
	I2CSPIDriver(MODULE_NAME, px4::device_bus_to_wq(interface->get_device_id()), bus_option, bus, 0, device_type),
	_px4_barometer(interface->get_device_id()),
	_interface(interface),
	_prom(prom_buf.s),
	_device_type(device_type),
	_sample_perf(perf_alloc(PC_ELAPSED, MODULE_NAME": read")),
	_measure_perf(perf_alloc(PC_ELAPSED, MODULE_NAME": measure")),
	_comms_errors(perf_alloc(PC_COUNT, MODULE_NAME": com_err"))
{
}

MS5611::~MS5611()
{
	// free perf counters
	perf_free(_sample_perf);
	perf_free(_measure_perf);
	perf_free(_comms_errors);

	delete _interface;
}

int
MS5611::init()
{
	int ret;

	/* do a first measurement cycle to populate reports with valid data */
	_measure_phase = 0;

	while (true) {
		/* do temperature first */
		if (OK != measure()) {
			ret = -EIO;
			break;
		}

		px4_usleep(MS5611_CONVERSION_INTERVAL);

		if (OK != collect()) {
			ret = -EIO;
			break;
		}

		/* now do a pressure measurement */
		if (OK != measure()) {
			ret = -EIO;
			break;
		}

		px4_usleep(MS5611_CONVERSION_INTERVAL);

		if (OK != collect()) {
			ret = -EIO;
			break;
		}

		/* state machine will have generated a report, copy it out */
		const sensor_baro_s &brp = _px4_barometer.get();

		if (_device_type == MS5607_DEVICE) {
			if (brp.pressure < 520.0f) {
				/* This is likely not this device, abort */
				ret = -EINVAL;
				break;
			}
		}

		switch (_device_type) {
		default:

		/* fall through */
		case MS5611_DEVICE:
			_interface->set_device_type(DRV_BARO_DEVTYPE_MS5611);
			_px4_barometer.set_device_type(DRV_BARO_DEVTYPE_MS5611);
			break;

		case MS5607_DEVICE:
			_interface->set_device_type(DRV_BARO_DEVTYPE_MS5607);
			_px4_barometer.set_device_type(DRV_BARO_DEVTYPE_MS5607);
			break;
		}

		ret = OK;

		break;
	}

	if (ret == 0) {
		start();
	}

	return ret;
}

void
MS5611::start()
{
	/* reset the report ring and state machine */
	_collect_phase = false;
	_measure_phase = 0;

	/* schedule a cycle to start things */
	ScheduleDelayed(MS5611_CONVERSION_INTERVAL);
}

void
MS5611::RunImpl()
{
	int ret;
	unsigned dummy;

	/* collection phase? */
	if (_collect_phase) {

		/* perform collection */
		ret = collect();

		if (ret != OK) {
			if (ret == -6) {
				/*
				 * The ms5611 seems to regularly fail to respond to
				 * its address; this happens often enough that we'd rather not
				 * spam the console with a message for this.
				 */
			} else {
				//DEVICE_LOG("collection error %d", ret);
			}

			/* issue a reset command to the sensor */
			_interface->ioctl(IOCTL_RESET, dummy);
			/* reset the collection state machine and try again - we need
			 * to wait 2.8 ms after issuing the sensor reset command
			 * according to the MS5611 datasheet
			 */
			ScheduleDelayed(2800);
			return;
		}

		/* next phase is measurement */
		_collect_phase = false;
	}

	/* measurement phase */
	ret = measure();

	if (ret != OK) {
		/* issue a reset command to the sensor */
		_interface->ioctl(IOCTL_RESET, dummy);
		/* reset the collection state machine and try again */
		start();
		return;
	}

	/* next phase is collection */
	_collect_phase = true;

	/* schedule a fresh cycle call when the measurement is done */
	ScheduleDelayed(MS5611_CONVERSION_INTERVAL);
}

int
MS5611::measure()
{
	perf_begin(_measure_perf);

	/*
	 * In phase zero, request temperature; in other phases, request pressure.
	 */
	unsigned addr = (_measure_phase == 0) ? ADDR_CMD_CONVERT_D2 : ADDR_CMD_CONVERT_D1;

	/*
	 * Send the command to begin measuring.
	 */
	int ret = _interface->ioctl(IOCTL_MEASURE, addr);

	if (OK != ret) {
		perf_count(_comms_errors);
	}

	_px4_barometer.set_error_count(perf_event_count(_comms_errors));

	perf_end(_measure_perf);

	return ret;
}

int
MS5611::collect()
{
	uint32_t raw;

	perf_begin(_sample_perf);

	/* read the most recent measurement - read offset/size are hardcoded in the interface */
	const hrt_abstime timestamp_sample = hrt_absolute_time();
	int ret = _interface->read(0, (void *)&raw, 0);

	if (ret < 0) {
		perf_count(_comms_errors);
		perf_end(_sample_perf);
		return ret;
	}

	/* handle a measurement */
	if (_measure_phase == 0) {

		/* temperature offset (in ADC units) */
		int32_t dT = (int32_t)raw - ((int32_t)_prom.c5_reference_temp << 8);

		/* absolute temperature in centidegrees - note intermediate value is outside 32-bit range */
		int32_t TEMP = 2000 + (int32_t)(((int64_t)dT * _prom.c6_temp_coeff_temp) >> 23);

		/* base sensor scale/offset values */
		if (_device_type == MS5611_DEVICE) {
			/* Perform MS5611 Caculation */
			_OFF  = ((int64_t)_prom.c2_pressure_offset << 16) + (((int64_t)_prom.c4_temp_coeff_pres_offset * dT) >> 7);
			_SENS = ((int64_t)_prom.c1_pressure_sens << 15) + (((int64_t)_prom.c3_temp_coeff_pres_sens * dT) >> 8);

			/* MS5611 temperature compensation */
			if (TEMP < 2000) {

				int32_t T2 = POW2(dT) >> 31;

				int64_t f = POW2((int64_t)TEMP - 2000);
				int64_t OFF2 = 5 * f >> 1;
				int64_t SENS2 = 5 * f >> 2;

				if (TEMP < -1500) {

					int64_t f2 = POW2(TEMP + 1500);
					OFF2 += 7 * f2;
					SENS2 += 11 * f2 >> 1;
				}

				TEMP -= T2;
				_OFF  -= OFF2;
				_SENS -= SENS2;
			}

		} else if (_device_type == MS5607_DEVICE) {
			/* Perform MS5607 Caculation */
			_OFF  = ((int64_t)_prom.c2_pressure_offset << 17) + (((int64_t)_prom.c4_temp_coeff_pres_offset * dT) >> 6);
			_SENS = ((int64_t)_prom.c1_pressure_sens << 16) + (((int64_t)_prom.c3_temp_coeff_pres_sens * dT) >> 7);

			/* MS5607 temperature compensation */
			if (TEMP < 2000) {

				int32_t T2 = POW2(dT) >> 31;

				int64_t f = POW2((int64_t)TEMP - 2000);
				int64_t OFF2 = 61 * f >> 4;
				int64_t SENS2 = 2 * f;

				if (TEMP < -1500) {
					int64_t f2 = POW2(TEMP + 1500);
					OFF2 += 15 * f2;
					SENS2 += 8 * f2;
				}

				TEMP -= T2;
				_OFF  -= OFF2;
				_SENS -= SENS2;
			}
		}

		float temperature = TEMP / 100.0f;
		_px4_barometer.set_temperature(temperature);

	} else {
		/* pressure calculation, result in Pa */
		int32_t P = (((raw * _SENS) >> 21) - _OFF) >> 15;

		float pressure = P / 100.0f;		/* convert to millibar */

		_px4_barometer.update(timestamp_sample, pressure);
	}

	/* update the measurement state machine */
	INCREMENT(_measure_phase, MS5611_MEASUREMENT_RATIO + 1);

	perf_end(_sample_perf);

	return OK;
}

void MS5611::print_status()
{
	I2CSPIDriverBase::print_status();
	perf_print_counter(_sample_perf);
	perf_print_counter(_comms_errors);

	printf("device:         %s\n", _device_type == MS5611_DEVICE ? "ms5611" : "ms5607");

	_px4_barometer.print_status();
}

namespace ms5611
{

/**
 * MS5611 crc4 cribbed from the datasheet
 */
bool
crc4(uint16_t *n_prom)
{
	int16_t cnt;
	uint16_t n_rem;
	uint16_t crc_read;
	uint8_t n_bit;

	n_rem = 0x00;

	/* save the read crc */
	crc_read = n_prom[7];

	/* remove CRC byte */
	n_prom[7] = (0xFF00 & (n_prom[7]));

	for (cnt = 0; cnt < 16; cnt++) {
		/* uneven bytes */
		if (cnt & 1) {
			n_rem ^= (uint8_t)((n_prom[cnt >> 1]) & 0x00FF);

		} else {
			n_rem ^= (uint8_t)(n_prom[cnt >> 1] >> 8);
		}

		for (n_bit = 8; n_bit > 0; n_bit--) {
			if (n_rem & 0x8000) {
				n_rem = (n_rem << 1) ^ 0x3000;

			} else {
				n_rem = (n_rem << 1);
			}
		}
	}

	/* final 4 bit remainder is CRC value */
	n_rem = (0x000F & (n_rem >> 12));
	n_prom[7] = crc_read;

	/* return true if CRCs match */
	return (0x000F & crc_read) == (n_rem ^ 0x00);
}

} // namespace ms5611