/****************************************************************************
*
* Copyright (C) 2012-2013 PX4 Development Team. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name PX4 nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/**
* @file ms5611.cpp
* Driver for the MS5611 barometric pressure sensor connected via I2C or SPI.
*/
#include <nuttx/config.h>
#include <sys/types.h>
#include <stdint.h>
#include <stdbool.h>
#include <stdlib.h>
#include <semaphore.h>
#include <string.h>
#include <fcntl.h>
#include <poll.h>
#include <errno.h>
#include <stdio.h>
#include <math.h>
#include <unistd.h>
#include <nuttx/arch.h>
#include <nuttx/wqueue.h>
#include <nuttx/clock.h>
#include <arch/board/board.h>
#include <drivers/device/device.h>
#include <drivers/drv_baro.h>
#include <drivers/drv_hrt.h>
#include <drivers/device/ringbuffer.h>
#include <systemlib/perf_counter.h>
#include <systemlib/err.h>
#include "ms5611.h"
/* oddly, ERROR is not defined for c++ */
#ifdef ERROR
# undef ERROR
#endif
static const int ERROR = -1;
#ifndef CONFIG_SCHED_WORKQUEUE
# error This requires CONFIG_SCHED_WORKQUEUE.
#endif
/* helper macro for handling report buffer indices */
#define INCREMENT(_x, _lim) do { __typeof__(_x) _tmp = _x+1; if (_tmp >= _lim) _tmp = 0; _x = _tmp; } while(0)
/* helper macro for arithmetic - returns the square of the argument */
#define POW2(_x) ((_x) * (_x))
/*
* MS5611 internal constants and data structures.
*/
/* internal conversion time: 9.17 ms, so should not be read at rates higher than 100 Hz */
#define MS5611_CONVERSION_INTERVAL 10000 /* microseconds */
#define MS5611_MEASUREMENT_RATIO 3 /* pressure measurements per temperature measurement */
class MS5611 : public device::CDev
{
public:
MS5611(device::Device *interface, ms5611::prom_u &prom_buf);
~MS5611();
virtual int init();
virtual ssize_t read(struct file *filp, char *buffer, size_t buflen);
virtual int ioctl(struct file *filp, int cmd, unsigned long arg);
/**
* Diagnostics - print some basic information about the driver.
*/
void print_info();
protected:
Device *_interface;
ms5611::prom_s _prom;
struct work_s _work;
unsigned _measure_ticks;
RingBuffer *_reports;
bool _collect_phase;
unsigned _measure_phase;
/* intermediate temperature values per MS5611 datasheet */
int32_t _TEMP;
int64_t _OFF;
int64_t _SENS;
/* altitude conversion calibration */
unsigned _msl_pressure; /* in kPa */
orb_advert_t _baro_topic;
perf_counter_t _sample_perf;
perf_counter_t _measure_perf;
perf_counter_t _comms_errors;
perf_counter_t _buffer_overflows;
/**
* Initialize the automatic measurement state machine and start it.
*
* @note This function is called at open and error time. It might make sense
* to make it more aggressive about resetting the bus in case of errors.
*/
void start_cycle();
/**
* Stop the automatic measurement state machine.
*/
void stop_cycle();
/**
* Perform a poll cycle; collect from the previous measurement
* and start a new one.
*
* This is the heart of the measurement state machine. This function
* alternately starts a measurement, or collects the data from the
* previous measurement.
*
* When the interval between measurements is greater than the minimum
* measurement interval, a gap is inserted between collection
* and measurement to provide the most recent measurement possible
* at the next interval.
*/
void cycle();
/**
* Static trampoline from the workq context; because we don't have a
* generic workq wrapper yet.
*
* @param arg Instance pointer for the driver that is polling.
*/
static void cycle_trampoline(void *arg);
/**
* Issue a measurement command for the current state.
*
* @return OK if the measurement command was successful.
*/
virtual int measure();
/**
* Collect the result of the most recent measurement.
*/
virtual int collect();
};
/*
* Driver 'main' command.
*/
extern "C" __EXPORT int ms5611_main(int argc, char *argv[]);
MS5611::MS5611(device::Device *interface, ms5611::prom_u &prom_buf) :
CDev("MS5611", BARO_DEVICE_PATH),
_interface(interface),
_prom(prom_buf.s),
_measure_ticks(0),
_reports(nullptr),
_collect_phase(false),
_measure_phase(0),
_TEMP(0),
_OFF(0),
_SENS(0),
_msl_pressure(101325),
_baro_topic(-1),
_sample_perf(perf_alloc(PC_ELAPSED, "ms5611_read")),
_measure_perf(perf_alloc(PC_ELAPSED, "ms5611_measure")),
_comms_errors(perf_alloc(PC_COUNT, "ms5611_comms_errors")),
_buffer_overflows(perf_alloc(PC_COUNT, "ms5611_buffer_overflows"))
{
// work_cancel in stop_cycle called from the dtor will explode if we don't do this...
memset(&_work, 0, sizeof(_work));
}
MS5611::~MS5611()
{
/* make sure we are truly inactive */
stop_cycle();
/* free any existing reports */
if (_reports != nullptr)
delete _reports;
// free perf counters
perf_free(_sample_perf);
perf_free(_measure_perf);
perf_free(_comms_errors);
perf_free(_buffer_overflows);
delete _interface;
}
int
MS5611::init()
{
int ret;
ret = CDev::init();
if (ret != OK) {
debug("CDev init failed");
goto out;
}
/* allocate basic report buffers */
_reports = new RingBuffer(2, sizeof(baro_report));
if (_reports == nullptr) {
debug("can't get memory for reports");
ret = -ENOMEM;
goto out;
}
/* get a publish handle on the baro topic */
struct baro_report zero_report;
memset(&zero_report, 0, sizeof(zero_report));
_baro_topic = orb_advertise(ORB_ID(sensor_baro), &zero_report);
if (_baro_topic < 0) {
debug("failed to create sensor_baro object");
ret = -ENOSPC;
goto out;
}
ret = OK;
out:
return ret;
}
ssize_t
MS5611::read(struct file *filp, char *buffer, size_t buflen)
{
unsigned count = buflen / sizeof(struct baro_report);
struct baro_report *brp = reinterpret_cast<struct baro_report *>(buffer);
int ret = 0;
/* buffer must be large enough */
if (count < 1)
return -ENOSPC;
/* if automatic measurement is enabled */
if (_measure_ticks > 0) {
/*
* While there is space in the caller's buffer, and reports, copy them.
* Note that we may be pre-empted by the workq thread while we are doing this;
* we are careful to avoid racing with them.
*/
while (count--) {
if (_reports->get(brp)) {
ret += sizeof(*brp);
brp++;
}
}
/* if there was no data, warn the caller */
return ret ? ret : -EAGAIN;
}
/* manual measurement - run one conversion */
do {
_measure_phase = 0;
_reports->flush();
/* do temperature first */
if (OK != measure()) {
ret = -EIO;
break;
}
usleep(MS5611_CONVERSION_INTERVAL);
if (OK != collect()) {
ret = -EIO;
break;
}
/* now do a pressure measurement */
if (OK != measure()) {
ret = -EIO;
break;
}
usleep(MS5611_CONVERSION_INTERVAL);
if (OK != collect()) {
ret = -EIO;
break;
}
/* state machine will have generated a report, copy it out */
if (_reports->get(brp))
ret = sizeof(*brp);
} while (0);
return ret;
}
int
MS5611::ioctl(struct file *filp, int cmd, unsigned long arg)
{
switch (cmd) {
case SENSORIOCSPOLLRATE: {
switch (arg) {
/* switching to manual polling */
case SENSOR_POLLRATE_MANUAL:
stop_cycle();
_measure_ticks = 0;
return OK;
/* external signalling not supported */
case SENSOR_POLLRATE_EXTERNAL:
/* zero would be bad */
case 0:
return -EINVAL;
/* set default/max polling rate */
case SENSOR_POLLRATE_MAX:
case SENSOR_POLLRATE_DEFAULT: {
/* do we need to start internal polling? */
bool want_start = (_measure_ticks == 0);
/* set interval for next measurement to minimum legal value */
_measure_ticks = USEC2TICK(MS5611_CONVERSION_INTERVAL);
/* if we need to start the poll state machine, do it */
if (want_start)
start_cycle();
return OK;
}
/* adjust to a legal polling interval in Hz */
default: {
/* do we need to start internal polling? */
bool want_start = (_measure_ticks == 0);
/* convert hz to tick interval via microseconds */
unsigned ticks = USEC2TICK(1000000 / arg);
/* check against maximum rate */
if (ticks < USEC2TICK(MS5611_CONVERSION_INTERVAL))
return -EINVAL;
/* update interval for next measurement */
_measure_ticks = ticks;
/* if we need to start the poll state machine, do it */
if (want_start)
start_cycle();
return OK;
}
}
}
case SENSORIOCGPOLLRATE:
if (_measure_ticks == 0)
return SENSOR_POLLRATE_MANUAL;
return (1000 / _measure_ticks);
case SENSORIOCSQUEUEDEPTH: {
/* lower bound is mandatory, upper bound is a sanity check */
if ((arg < 1) || (arg > 100))
return -EINVAL;
irqstate_t flags = irqsave();
if (!_reports->resize(arg)) {
irqrestore(flags);
return -ENOMEM;
}
irqrestore(flags);
return OK;
}
case SENSORIOCGQUEUEDEPTH:
return _reports->size();
case SENSORIOCRESET:
/* XXX implement this */
return -EINVAL;
case BAROIOCSMSLPRESSURE:
/* range-check for sanity */
if ((arg < 80000) || (arg > 120000))
return -EINVAL;
_msl_pressure = arg;
return OK;
case BAROIOCGMSLPRESSURE:
return _msl_pressure;
default:
break;
}
/* give it to the bus-specific superclass */
// return bus_ioctl(filp, cmd, arg);
return CDev::ioctl(filp, cmd, arg);
}
void
MS5611::start_cycle()
{
/* reset the report ring and state machine */
_collect_phase = false;
_measure_phase = 0;
_reports->flush();
/* schedule a cycle to start things */
work_queue(HPWORK, &_work, (worker_t)&MS5611::cycle_trampoline, this, 1);
}
void
MS5611::stop_cycle()
{
work_cancel(HPWORK, &_work);
}
void
MS5611::cycle_trampoline(void *arg)
{
MS5611 *dev = reinterpret_cast<MS5611 *>(arg);
dev->cycle();
}
void
MS5611::cycle()
{
int ret;
/* 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 {
//log("collection error %d", ret);
}
/* reset the collection state machine and try again */
start_cycle();
return;
}
/* next phase is measurement */
_collect_phase = false;
/*
* Is there a collect->measure gap?
* Don't inject one after temperature measurements, so we can keep
* doing pressure measurements at something close to the desired rate.
*/
if ((_measure_phase != 0) &&
(_measure_ticks > USEC2TICK(MS5611_CONVERSION_INTERVAL))) {
/* schedule a fresh cycle call when we are ready to measure again */
work_queue(HPWORK,
&_work,
(worker_t)&MS5611::cycle_trampoline,
this,
_measure_ticks - USEC2TICK(MS5611_CONVERSION_INTERVAL));
return;
}
}
/* measurement phase */
ret = measure();
if (ret != OK) {
//log("measure error %d", ret);
/* reset the collection state machine and try again */
start_cycle();
return;
}
/* next phase is collection */
_collect_phase = true;
/* schedule a fresh cycle call when the measurement is done */
work_queue(HPWORK,
&_work,
(worker_t)&MS5611::cycle_trampoline,
this,
USEC2TICK(MS5611_CONVERSION_INTERVAL));
}
int
MS5611::measure()
{
int ret;
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.
*/
ret = _interface->ioctl(IOCTL_MEASURE, addr);
if (OK != ret)
perf_count(_comms_errors);
perf_end(_measure_perf);
return ret;
}
int
MS5611::collect()
{
int ret;
uint32_t raw;
perf_begin(_sample_perf);
struct baro_report report;
/* this should be fairly close to the end of the conversion, so the best approximation of the time */
report.timestamp = hrt_absolute_time();
report.error_count = perf_event_count(_comms_errors);
/* read the most recent measurement - read offset/size are hardcoded in the interface */
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 */
_TEMP = 2000 + (int32_t)(((int64_t)dT * _prom.c6_temp_coeff_temp) >> 23);
/* base sensor scale/offset values */
_SENS = ((int64_t)_prom.c1_pressure_sens << 15) + (((int64_t)_prom.c3_temp_coeff_pres_sens * dT) >> 8);
_OFF = ((int64_t)_prom.c2_pressure_offset << 16) + (((int64_t)_prom.c4_temp_coeff_pres_offset * dT) >> 7);
/* 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 {
/* pressure calculation, result in Pa */
int32_t P = (((raw * _SENS) >> 21) - _OFF) >> 15;
/* generate a new report */
report.temperature = _TEMP / 100.0f;
report.pressure = P / 100.0f; /* convert to millibar */
/* altitude calculations based on http://www.kansasflyer.org/index.asp?nav=Avi&sec=Alti&tab=Theory&pg=1 */
/*
* PERFORMANCE HINT:
*
* The single precision calculation is 50 microseconds faster than the double
* precision variant. It is however not obvious if double precision is required.
* Pending more inspection and tests, we'll leave the double precision variant active.
*
* Measurements:
* double precision: ms5611_read: 992 events, 258641us elapsed, min 202us max 305us
* single precision: ms5611_read: 963 events, 208066us elapsed, min 202us max 241us
*/
/* tropospheric properties (0-11km) for standard atmosphere */
const double T1 = 15.0 + 273.15; /* temperature at base height in Kelvin */
const double a = -6.5 / 1000; /* temperature gradient in degrees per metre */
const double g = 9.80665; /* gravity constant in m/s/s */
const double R = 287.05; /* ideal gas constant in J/kg/K */
/* current pressure at MSL in kPa */
double p1 = _msl_pressure / 1000.0;
/* measured pressure in kPa */
double p = P / 1000.0;
/*
* Solve:
*
* / -(aR / g) \
* | (p / p1) . T1 | - T1
* \ /
* h = ------------------------------- + h1
* a
*/
report.altitude = (((pow((p / p1), (-(a * R) / g))) * T1) - T1) / a;
/* publish it */
orb_publish(ORB_ID(sensor_baro), _baro_topic, &report);
if (_reports->force(&report)) {
perf_count(_buffer_overflows);
}
/* notify anyone waiting for data */
poll_notify(POLLIN);
}
/* update the measurement state machine */
INCREMENT(_measure_phase, MS5611_MEASUREMENT_RATIO + 1);
perf_end(_sample_perf);
return OK;
}
void
MS5611::print_info()
{
perf_print_counter(_sample_perf);
perf_print_counter(_comms_errors);
perf_print_counter(_buffer_overflows);
printf("poll interval: %u ticks\n", _measure_ticks);
_reports->print_info("report queue");
printf("TEMP: %d\n", _TEMP);
printf("SENS: %lld\n", _SENS);
printf("OFF: %lld\n", _OFF);
printf("MSL pressure: %10.4f\n", (double)(_msl_pressure / 100.f));
printf("factory_setup %u\n", _prom.factory_setup);
printf("c1_pressure_sens %u\n", _prom.c1_pressure_sens);
printf("c2_pressure_offset %u\n", _prom.c2_pressure_offset);
printf("c3_temp_coeff_pres_sens %u\n", _prom.c3_temp_coeff_pres_sens);
printf("c4_temp_coeff_pres_offset %u\n", _prom.c4_temp_coeff_pres_offset);
printf("c5_reference_temp %u\n", _prom.c5_reference_temp);
printf("c6_temp_coeff_temp %u\n", _prom.c6_temp_coeff_temp);
printf("serial_and_crc %u\n", _prom.serial_and_crc);
}
/**
* Local functions in support of the shell command.
*/
namespace ms5611
{
MS5611 *g_dev;
void start();
void test();
void reset();
void info();
void calibrate(unsigned altitude);
/**
* 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);
}
/**
* Start the driver.
*/
void
start()
{
int fd;
prom_u prom_buf;
if (g_dev != nullptr)
/* if already started, the still command succeeded */
errx(0, "already started");
device::Device *interface = nullptr;
/* create the driver, try SPI first, fall back to I2C if unsuccessful */
if (MS5611_spi_interface != nullptr)
interface = MS5611_spi_interface(prom_buf);
if (interface == nullptr && (MS5611_i2c_interface != nullptr))
interface = MS5611_i2c_interface(prom_buf);
if (interface == nullptr)
errx(1, "failed to allocate an interface");
if (interface->init() != OK) {
delete interface;
errx(1, "interface init failed");
}
g_dev = new MS5611(interface, prom_buf);
if (g_dev == nullptr) {
delete interface;
errx(1, "failed to allocate driver");
}
if (g_dev->init() != OK)
goto fail;
/* set the poll rate to default, starts automatic data collection */
fd = open(BARO_DEVICE_PATH, O_RDONLY);
if (fd < 0) {
warnx("can't open baro device");
goto fail;
}
if (ioctl(fd, SENSORIOCSPOLLRATE, SENSOR_POLLRATE_DEFAULT) < 0) {
warnx("failed setting default poll rate");
goto fail;
}
exit(0);
fail:
if (g_dev != nullptr) {
delete g_dev;
g_dev = nullptr;
}
errx(1, "driver start failed");
}
/**
* Perform some basic functional tests on the driver;
* make sure we can collect data from the sensor in polled
* and automatic modes.
*/
void
test()
{
struct baro_report report;
ssize_t sz;
int ret;
int fd = open(BARO_DEVICE_PATH, O_RDONLY);
if (fd < 0)
err(1, "%s open failed (try 'ms5611 start' if the driver is not running)", BARO_DEVICE_PATH);
/* do a simple demand read */
sz = read(fd, &report, sizeof(report));
if (sz != sizeof(report))
err(1, "immediate read failed");
warnx("single read");
warnx("pressure: %10.4f", (double)report.pressure);
warnx("altitude: %11.4f", (double)report.altitude);
warnx("temperature: %8.4f", (double)report.temperature);
warnx("time: %lld", report.timestamp);
/* set the queue depth to 10 */
if (OK != ioctl(fd, SENSORIOCSQUEUEDEPTH, 10))
errx(1, "failed to set queue depth");
/* start the sensor polling at 2Hz */
if (OK != ioctl(fd, SENSORIOCSPOLLRATE, 2))
errx(1, "failed to set 2Hz poll rate");
/* read the sensor 5x and report each value */
for (unsigned i = 0; i < 5; i++) {
struct pollfd fds;
/* wait for data to be ready */
fds.fd = fd;
fds.events = POLLIN;
ret = poll(&fds, 1, 2000);
if (ret != 1)
errx(1, "timed out waiting for sensor data");
/* now go get it */
sz = read(fd, &report, sizeof(report));
if (sz != sizeof(report))
err(1, "periodic read failed");
warnx("periodic read %u", i);
warnx("pressure: %10.4f", (double)report.pressure);
warnx("altitude: %11.4f", (double)report.altitude);
warnx("temperature: %8.4f", (double)report.temperature);
warnx("time: %lld", report.timestamp);
}
errx(0, "PASS");
}
/**
* Reset the driver.
*/
void
reset()
{
int fd = open(BARO_DEVICE_PATH, O_RDONLY);
if (fd < 0)
err(1, "failed ");
if (ioctl(fd, SENSORIOCRESET, 0) < 0)
err(1, "driver reset failed");
if (ioctl(fd, SENSORIOCSPOLLRATE, SENSOR_POLLRATE_DEFAULT) < 0)
err(1, "driver poll restart failed");
exit(0);
}
/**
* Print a little info about the driver.
*/
void
info()
{
if (g_dev == nullptr)
errx(1, "driver not running");
printf("state @ %p\n", g_dev);
g_dev->print_info();
exit(0);
}
/**
* Calculate actual MSL pressure given current altitude
*/
void
calibrate(unsigned altitude)
{
struct baro_report report;
float pressure;
float p1;
int fd = open(BARO_DEVICE_PATH, O_RDONLY);
if (fd < 0)
err(1, "%s open failed (try 'ms5611 start' if the driver is not running)", BARO_DEVICE_PATH);
/* start the sensor polling at max */
if (OK != ioctl(fd, SENSORIOCSPOLLRATE, SENSOR_POLLRATE_MAX))
errx(1, "failed to set poll rate");
/* average a few measurements */
pressure = 0.0f;
for (unsigned i = 0; i < 20; i++) {
struct pollfd fds;
int ret;
ssize_t sz;
/* wait for data to be ready */
fds.fd = fd;
fds.events = POLLIN;
ret = poll(&fds, 1, 1000);
if (ret != 1)
errx(1, "timed out waiting for sensor data");
/* now go get it */
sz = read(fd, &report, sizeof(report));
if (sz != sizeof(report))
err(1, "sensor read failed");
pressure += report.pressure;
}
pressure /= 20; /* average */
pressure /= 10; /* scale from millibar to kPa */
/* tropospheric properties (0-11km) for standard atmosphere */
const float T1 = 15.0 + 273.15; /* temperature at base height in Kelvin */
const float a = -6.5 / 1000; /* temperature gradient in degrees per metre */
const float g = 9.80665f; /* gravity constant in m/s/s */
const float R = 287.05f; /* ideal gas constant in J/kg/K */
warnx("averaged pressure %10.4fkPa at %um", (double)pressure, altitude);
p1 = pressure * (powf(((T1 + (a * (float)altitude)) / T1), (g / (a * R))));
warnx("calculated MSL pressure %10.4fkPa", (double)p1);
/* save as integer Pa */
p1 *= 1000.0f;
if (ioctl(fd, BAROIOCSMSLPRESSURE, (unsigned long)p1) != OK)
err(1, "BAROIOCSMSLPRESSURE");
exit(0);
}
} // namespace
int
ms5611_main(int argc, char *argv[])
{
/*
* Start/load the driver.
*/
if (!strcmp(argv[1], "start"))
ms5611::start();
/*
* Test the driver/device.
*/
if (!strcmp(argv[1], "test"))
ms5611::test();
/*
* Reset the driver.
*/
if (!strcmp(argv[1], "reset"))
ms5611::reset();
/*
* Print driver information.
*/
if (!strcmp(argv[1], "info"))
ms5611::info();
/*
* Perform MSL pressure calibration given an altitude in metres
*/
if (!strcmp(argv[1], "calibrate")) {
if (argc < 2)
errx(1, "missing altitude");
long altitude = strtol(argv[2], nullptr, 10);
ms5611::calibrate(altitude);
}
errx(1, "unrecognised command, try 'start', 'test', 'reset' or 'info'");
}