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px4-firmware/apps/drivers/hmc5883/hmc5883.cpp

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/****************************************************************************
*
* Copyright (C) 2012 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 hmc5883.cpp
*
* Driver for the HMC5883 magnetometer connected via I2C.
*/
#include <nuttx/config.h>
#include <drivers/device/i2c.h>
#include <sys/types.h>
#include <stdint.h>
#include <stdlib.h>
#include <stdbool.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/up_hrt.h>
#include <systemlib/perf_counter.h>
#include <systemlib/err.h>
#include <drivers/drv_mag.h>
/*
* HMC5883 internal constants and data structures.
*/
/* Max measurement rate is 160Hz */
#define HMC5883_CONVERSION_INTERVAL (1000000 / 160) /* microseconds */
#define ADDR_CONF_A 0x00
#define ADDR_CONF_B 0x01
#define ADDR_MODE 0x02
#define ADDR_DATA_OUT_X_MSB 0x03
#define ADDR_DATA_OUT_X_LSB 0x04
#define ADDR_DATA_OUT_Z_MSB 0x05
#define ADDR_DATA_OUT_Z_LSB 0x06
#define ADDR_DATA_OUT_Y_MSB 0x07
#define ADDR_DATA_OUT_Y_LSB 0x08
#define ADDR_STATUS 0x09
#define ADDR_ID_A 0x0a
#define ADDR_ID_B 0x0b
#define ADDR_ID_C 0x0c
#define HMC5883L_ADDRESS 0x1E
/* modes not changeable outside of driver */
#define HMC5883L_MODE_NORMAL (0 << 0) /* default */
#define HMC5883L_MODE_POSITIVE_BIAS (1 << 0) /* positive bias */
#define HMC5883L_MODE_NEGATIVE_BIAS (1 << 1) /* negative bias */
#define HMC5883L_AVERAGING_1 (0 << 5) /* conf a register */
#define HMC5883L_AVERAGING_2 (1 << 5)
#define HMC5883L_AVERAGING_4 (2 << 5)
#define HMC5883L_AVERAGING_8 (3 << 5)
#define MODE_REG_CONTINOUS_MODE (0 << 0)
#define MODE_REG_SINGLE_MODE (1 << 0) /* default */
#define STATUS_REG_DATA_OUT_LOCK (1 << 1) /* page 16: set if data is only partially read, read device to reset */
#define STATUS_REG_DATA_READY (1 << 0) /* page 16: set if all axes have valid measurements */
#define ID_A_WHO_AM_I 'H'
#define ID_B_WHO_AM_I '4'
#define ID_C_WHO_AM_I '3'
/* oddly, ERROR is not defined for c++ */
#ifdef ERROR
# undef ERROR
#endif
static const int ERROR = -1;
class HMC5883 : public device::I2C
{
public:
HMC5883(int bus);
~HMC5883();
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:
virtual int probe();
private:
work_s _work;
unsigned _measure_ticks;
unsigned _num_reports;
volatile unsigned _next_report;
volatile unsigned _oldest_report;
mag_report *_reports;
mag_scale _scale;
float _range_scale;
float _range_ga;
bool _collect_phase;
orb_advert_t _mag_topic;
perf_counter_t _sample_perf;
perf_counter_t _comms_errors;
perf_counter_t _buffer_overflows;
/**
* Test whether the device supported by the driver is present at a
* specific address.
*
* @param address The I2C bus address to probe.
* @return True if the device is present.
*/
int probe_address(uint8_t address);
/**
* Initialise 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();
/**
* Stop the automatic measurement state machine.
*/
void stop();
/**
* Perform the on-sensor scale calibration routine.
*
* @note The sensor will continue to provide measurements, these
* will however reflect the uncalibrated sensor state until
* the calibration routine has been completed.
*
* @param enable set to 1 to enable self-test strap, 0 to disable
*/
int calibrate(unsigned enable);
/**
* Set the sensor range.
*
* Sets the internal range to handle at least the argument in Gauss.
*/
int set_range(unsigned range);
/**
* 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);
/**
* Write a register.
*
* @param reg The register to write.
* @param val The value to write.
* @return OK on write success.
*/
int write_reg(uint8_t reg, uint8_t val);
/**
* Read a register.
*
* @param reg The register to read.
* @param val The value read.
* @return OK on read success.
*/
int read_reg(uint8_t reg, uint8_t &val);
/**
* Issue a measurement command.
*
* @return OK if the measurement command was successful.
*/
int measure();
/**
* Collect the result of the most recent measurement.
*/
int collect();
/**
* Convert a big-endian signed 16-bit value to a float.
*
* @param in A signed 16-bit big-endian value.
* @return The floating-point representation of the value.
*/
float meas_to_float(uint8_t in[2]);
};
/* helper macro for handling report buffer indices */
#define INCREMENT(_x, _lim) do { _x++; if (_x >= _lim) _x = 0; } while(0)
/*
* Driver 'main' command.
*/
extern "C" __EXPORT int hmc5883_main(int argc, char *argv[]);
HMC5883::HMC5883(int bus) :
I2C("HMC5883", MAG_DEVICE_PATH, bus, HMC5883L_ADDRESS, 400000),
_measure_ticks(0),
_num_reports(0),
_next_report(0),
_oldest_report(0),
_reports(nullptr),
_mag_topic(-1),
_range_scale(0), /* default range scale from counts to gauss */
_range_ga(1.3f),
_sample_perf(perf_alloc(PC_ELAPSED, "hmc5883_read")),
_comms_errors(perf_alloc(PC_COUNT, "hmc5883_comms_errors")),
_buffer_overflows(perf_alloc(PC_COUNT, "hmc5883_buffer_overflows"))
{
// enable debug() calls
_debug_enabled = true;
// default scaling
_scale.x_offset = 0;
_scale.x_scale = 1.0f;
_scale.y_offset = 0;
_scale.y_scale = 1.0f;
_scale.z_offset = 0;
_scale.z_scale = 1.0f;
// work_cancel in the dtor will explode if we don't do this...
memset(&_work, 0, sizeof(_work));
}
HMC5883::~HMC5883()
{
/* make sure we are truly inactive */
stop();
/* free any existing reports */
if (_reports != nullptr)
delete[] _reports;
}
int
HMC5883::init()
{
int ret = ERROR;
/* do I2C init (and probe) first */
if (I2C::init() != OK)
goto out;
/* allocate basic report buffers */
_num_reports = 2;
_reports = new struct mag_report[_num_reports];
if (_reports == nullptr)
goto out;
_oldest_report = _next_report = 0;
/* get a publish handle on the mag topic */
memset(&_reports[0], 0, sizeof(_reports[0]));
_mag_topic = orb_advertise(ORB_ID(sensor_mag), &_reports[0]);
if (_mag_topic < 0)
debug("failed to create sensor_mag object");
/* set range */
set_range(_range_ga);
ret = OK;
out:
return ret;
}
int HMC5883::set_range(unsigned range)
{
uint8_t range_bits;
if (range < 1) {
range_bits = 0x00;
_range_scale = 1.0f / 1370.0f;
_range_ga = 0.88f;
} else if (range <= 1) {
range_bits = 0x01;
_range_scale = 1.0f / 1090.0f;
_range_ga = 1.3f;
} else if (range <= 2) {
range_bits = 0x02;
_range_scale = 1.0f / 820.0f;
_range_ga = 1.9f;
} else if (range <= 3) {
range_bits = 0x03;
_range_scale = 1.0f / 660.0f;
_range_ga = 2.5f;
} else if (range <= 4) {
range_bits = 0x04;
_range_scale = 1.0f / 440.0f;
_range_ga = 4.0f;
} else if (range <= 4.7f) {
range_bits = 0x05;
_range_scale = 1.0f / 390.0f;
_range_ga = 4.7f;
} else if (range <= 5.6f) {
range_bits = 0x06;
_range_scale = 1.0f / 330.0f;
_range_ga = 5.6f;
} else {
range_bits = 0x07;
_range_scale = 1.0f / 230.0f;
_range_ga = 8.1f;
}
int ret;
/*
* Send the command to set the range
*/
ret = write_reg(ADDR_CONF_B, (range_bits << 5));
if (OK != ret)
perf_count(_comms_errors);
uint8_t range_bits_in;
ret = read_reg(ADDR_CONF_B, range_bits_in);
if (OK != ret)
perf_count(_comms_errors);
return !(range_bits_in == (range_bits << 5));
}
int
HMC5883::probe()
{
uint8_t data[3] = {0, 0, 0};
_retries = 10;
if (read_reg(ADDR_ID_A, data[0]) ||
read_reg(ADDR_ID_B, data[1]) ||
read_reg(ADDR_ID_C, data[2]))
debug("read_reg fail");
_retries = 1;
if ((data[0] != ID_A_WHO_AM_I) ||
(data[1] != ID_B_WHO_AM_I) ||
(data[2] != ID_C_WHO_AM_I)) {
debug("ID byte mismatch (%02x,%02x,%02x)", data[0], data[1], data[2]);
return -EIO;
}
return OK;
}
ssize_t
HMC5883::read(struct file *filp, char *buffer, size_t buflen)
{
unsigned count = buflen / sizeof(struct mag_report);
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 (_oldest_report != _next_report) {
memcpy(buffer, _reports + _oldest_report, sizeof(*_reports));
ret += sizeof(_reports[0]);
INCREMENT(_oldest_report, _num_reports);
}
}
/* if there was no data, warn the caller */
return ret ? ret : -EAGAIN;
}
/* manual measurement - run one conversion */
/* XXX really it'd be nice to lock against other readers here */
do {
_oldest_report = _next_report = 0;
/* trigger a measurement */
if (OK != measure()) {
ret = -EIO;
break;
}
/* wait for it to complete */
usleep(HMC5883_CONVERSION_INTERVAL);
/* run the collection phase */
if (OK != collect()) {
ret = -EIO;
break;
}
/* state machine will have generated a report, copy it out */
memcpy(buffer, _reports, sizeof(*_reports));
ret = sizeof(*_reports);
} while (0);
return ret;
}
int
HMC5883::ioctl(struct file *filp, int cmd, unsigned long arg)
{
switch (cmd) {
case SENSORIOCSPOLLRATE: {
switch (arg) {
/* switching to manual polling */
case SENSOR_POLLRATE_MANUAL:
stop();
_measure_ticks = 0;
return OK;
/* external signalling (DRDY) 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(HMC5883_CONVERSION_INTERVAL);
/* if we need to start the poll state machine, do it */
if (want_start)
start();
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(HMC5883_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();
return OK;
}
}
}
case SENSORIOCGPOLLRATE:
if (_measure_ticks == 0)
return SENSOR_POLLRATE_MANUAL;
return (1000 / _measure_ticks);
case SENSORIOCSQUEUEDEPTH: {
/* add one to account for the sentinel in the ring */
arg++;
/* lower bound is mandatory, upper bound is a sanity check */
if ((arg < 2) || (arg > 100))
return -EINVAL;
/* allocate new buffer */
struct mag_report *buf = new struct mag_report[arg];
if (nullptr == buf)
return -ENOMEM;
/* reset the measurement state machine with the new buffer, free the old */
stop();
delete[] _reports;
_num_reports = arg;
_reports = buf;
start();
return OK;
}
case SENSORIOCGQUEUEDEPTH:
return _num_reports - 1;
case SENSORIOCRESET:
/* XXX implement this */
return -EINVAL;
case MAGIOCSSAMPLERATE:
/* not supported, always 1 sample per poll */
return -EINVAL;
case MAGIOCSRANGE:
return set_range(arg);
case MAGIOCSLOWPASS:
/* not supported, no internal filtering */
return -EINVAL;
case MAGIOCSSCALE:
/* set new scale factors */
memcpy(&_scale, (mag_scale *)arg, sizeof(_scale));
return 0;
case MAGIOCGSCALE:
/* copy out scale factors */
memcpy((mag_scale *)arg, &_scale, sizeof(_scale));
return 0;
case MAGIOCCALIBRATE:
return calibrate(arg);
default:
/* give it to the superclass */
return I2C::ioctl(filp, cmd, arg);
}
}
void
HMC5883::start()
{
/* reset the report ring and state machine */
_collect_phase = false;
_oldest_report = _next_report = 0;
/* schedule a cycle to start things */
work_queue(HPWORK, &_work, (worker_t)&HMC5883::cycle_trampoline, this, 1);
}
void
HMC5883::stop()
{
work_cancel(HPWORK, &_work);
}
void
HMC5883::cycle_trampoline(void *arg)
{
HMC5883 *dev = (HMC5883 *)arg;
dev->cycle();
}
void
HMC5883::cycle()
{
/* collection phase? */
if (_collect_phase) {
/* perform collection */
if (OK != collect()) {
log("collection error");
/* restart the measurement state machine */
start();
return;
}
/* next phase is measurement */
_collect_phase = false;
/*
* Is there a collect->measure gap?
*/
if (_measure_ticks > USEC2TICK(HMC5883_CONVERSION_INTERVAL)) {
/* schedule a fresh cycle call when we are ready to measure again */
work_queue(HPWORK,
&_work,
(worker_t)&HMC5883::cycle_trampoline,
this,
_measure_ticks - USEC2TICK(HMC5883_CONVERSION_INTERVAL));
return;
}
}
/* measurement phase */
if (OK != measure())
log("measure error");
/* next phase is collection */
_collect_phase = true;
/* schedule a fresh cycle call when the measurement is done */
work_queue(HPWORK,
&_work,
(worker_t)&HMC5883::cycle_trampoline,
this,
USEC2TICK(HMC5883_CONVERSION_INTERVAL));
}
int
HMC5883::measure()
{
int ret;
/*
* Send the command to begin a measurement.
*/
ret = write_reg(ADDR_MODE, MODE_REG_SINGLE_MODE);
if (OK != ret)
perf_count(_comms_errors);
return ret;
}
int
HMC5883::collect()
{
#pragma pack(push, 1)
struct { /* status register and data as read back from the device */
uint8_t x[2];
uint8_t z[2];
uint8_t y[2];
} hmc_report;
#pragma pack(pop)
struct {
int16_t x, y, z;
} report;
int ret = -EIO;
uint8_t cmd;
perf_begin(_sample_perf);
/* this should be fairly close to the end of the measurement, so the best approximation of the time */
_reports[_next_report].timestamp = hrt_absolute_time();
/*
* @note We could read the status register here, which could tell us that
* we were too early and that the output registers are still being
* written. In the common case that would just slow us down, and
* we're better off just never being early.
*/
/* get measurements from the device */
cmd = ADDR_DATA_OUT_X_MSB;
ret = transfer(&cmd, 1, (uint8_t *)&hmc_report, sizeof(hmc_report));
if (ret != OK) {
perf_count(_comms_errors);
debug("data/status read error");
goto out;
}
/* swap the data we just received */
report.x = (((int16_t)hmc_report.x[0]) << 8) + hmc_report.x[1];
report.y = (((int16_t)hmc_report.y[0]) << 8) + hmc_report.y[1];
report.z = (((int16_t)hmc_report.z[0]) << 8) + hmc_report.z[1];
/*
* If any of the values are -4096, there was an internal math error in the sensor.
* Generalise this to a simple range check that will also catch some bit errors.
*/
if ((abs(report.x) > 2048) ||
(abs(report.y) > 2048) ||
(abs(report.z) > 2048))
goto out;
/*
* RAW outputs
*
* to align the sensor axes with the board, x and y need to be flipped
* and y needs to be negated
*/
_reports[_next_report].x_raw = report.y;
_reports[_next_report].y_raw = ((report.x == -32768) ? 32767 : -report.x);
/* z remains z */
_reports[_next_report].z_raw = report.z;
/* scale values for output */
/*
* 1) Scale raw value to SI units using scaling from datasheet.
* 2) Subtract static offset (in SI units)
* 3) Scale the statically calibrated values with a linear
* dynamically obtained factor
*
* Note: the static sensor offset is the number the sensor outputs
* at a nominally 'zero' input. Therefore the offset has to
* be subtracted.
*
* Example: A gyro outputs a value of 74 at zero angular rate
* the offset is 74 from the origin and subtracting
* 74 from all measurements centers them around zero.
*/
/* to align the sensor axes with the board, x and y need to be flipped */
_reports[_next_report].x = ((report.y * _range_scale) - _scale.x_offset) * _scale.x_scale;
/* flip axes and negate value for y */
_reports[_next_report].y = ((((report.x == -32768) ? 32767 : -report.x) * _range_scale) - _scale.y_offset) * _scale.y_scale;
/* z remains z */
_reports[_next_report].z = ((report.z * _range_scale) - _scale.z_offset) * _scale.z_scale;
/* publish it */
orb_publish(ORB_ID(sensor_mag), _mag_topic, &_reports[_next_report]);
/* post a report to the ring - note, not locked */
INCREMENT(_next_report, _num_reports);
/* if we are running up against the oldest report, toss it */
if (_next_report == _oldest_report) {
perf_count(_buffer_overflows);
INCREMENT(_oldest_report, _num_reports);
}
/* notify anyone waiting for data */
poll_notify(POLLIN);
ret = OK;
out:
perf_end(_sample_perf);
return ret;
}
int HMC5883::calibrate(unsigned enable)
{
int ret;
/* arm the excitement strap */
uint8_t conf_reg;
ret = read_reg(ADDR_CONF_A, conf_reg);
if (OK != ret)
perf_count(_comms_errors);
if (enable) {
conf_reg |= 0x01;
} else {
conf_reg &= ~0x03;
}
ret = write_reg(ADDR_CONF_A, conf_reg);
if (OK != ret)
perf_count(_comms_errors);
uint8_t conf_reg_ret;
read_reg(ADDR_CONF_A, conf_reg_ret);
return !(conf_reg == conf_reg_ret);
}
int
HMC5883::write_reg(uint8_t reg, uint8_t val)
{
uint8_t cmd[] = { reg, val };
return transfer(&cmd[0], 2, nullptr, 0);
}
int
HMC5883::read_reg(uint8_t reg, uint8_t &val)
{
return transfer(&reg, 1, &val, 1);
}
float
HMC5883::meas_to_float(uint8_t in[2])
{
union {
uint8_t b[2];
int16_t w;
} u;
u.b[0] = in[1];
u.b[1] = in[0];
return (float) u.w;
}
void
HMC5883::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);
printf("report queue: %u (%u/%u @ %p)\n",
_num_reports, _oldest_report, _next_report, _reports);
}
/**
* Local functions in support of the shell command.
*/
namespace hmc5883
{
/* oddly, ERROR is not defined for c++ */
#ifdef ERROR
# undef ERROR
#endif
const int ERROR = -1;
HMC5883 *g_dev;
void start();
void test();
void reset();
void info();
int calibrate();
/**
* Start the driver.
*/
void
start()
{
int fd;
if (g_dev != nullptr)
errx(1, "already started");
/* create the driver */
/* XXX HORRIBLE hack - the bus number should not come from here */
g_dev = new HMC5883(2);
if (g_dev == nullptr)
goto fail;
if (OK != g_dev->init())
goto fail;
/* set the poll rate to default, starts automatic data collection */
fd = open(MAG_DEVICE_PATH, O_RDONLY);
if (fd < 0)
goto fail;
if (ioctl(fd, SENSORIOCSPOLLRATE, SENSOR_POLLRATE_DEFAULT) < 0)
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 mag_report report;
ssize_t sz;
int ret;
int fd = open(MAG_DEVICE_PATH, O_RDONLY);
if (fd < 0)
err(1, "%s open failed (try 'hmc5883 start' if the driver is not running", MAG_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("measurement: %.6f %.6f %.6f", (double)report.x, (double)report.y, (double)report.z);
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("measurement: %.6f %.6f %.6f", (double)report.x, (double)report.y, (double)report.z);
warnx("time: %lld", report.timestamp);
}
errx(0, "PASS");
}
/**
* Automatic scale calibration.
*
* Basic idea:
*
* output = (ext field +- 1.1 Ga self-test) * scale factor
*
* and consequently:
*
* 1.1 Ga = (excited - normal) * scale factor
* scale factor = (excited - normal) / 1.1 Ga
*
* sxy = (excited - normal) / 766 | for conf reg. B set to 0x60 / Gain = 3
* sz = (excited - normal) / 713 | for conf reg. B set to 0x60 / Gain = 3
*
* By subtracting the non-excited measurement the pure 1.1 Ga reading
* can be extracted and the sensitivity of all axes can be matched.
*
* SELF TEST OPERATION
* To check the HMC5883L for proper operation, a self test feature in incorporated
* in which the sensor offset straps are excited to create a nominal field strength
* (bias field) to be measured. To implement self test, the least significant bits
* (MS1 and MS0) of configuration register A are changed from 00 to 01 (positive bias)
* or 10 (negetive bias), e.g. 0x11 or 0x12.
* Then, by placing the mode register into single-measurement mode (0x01),
* two data acquisition cycles will be made on each magnetic vector.
* The first acquisition will be a set pulse followed shortly by measurement
* data of the external field. The second acquisition will have the offset strap
* excited (about 10 mA) in the positive bias mode for X, Y, and Z axes to create
* about a ±1.1 gauss self test field plus the external field. The first acquisition
* values will be subtracted from the second acquisition, and the net measurement
* will be placed into the data output registers.
* Since self test adds ~1.1 Gauss additional field to the existing field strength,
* using a reduced gain setting prevents sensor from being saturated and data registers
* overflowed. For example, if the configuration register B is set to 0x60 (Gain=3),
* values around +766 LSB (1.16 Ga * 660 LSB/Ga) will be placed in the X and Y data
* output registers and around +713 (1.08 Ga * 660 LSB/Ga) will be placed in Z data
* output register. To leave the self test mode, change MS1 and MS0 bit of the
* configuration register A back to 00 (Normal Measurement Mode), e.g. 0x10.
* Using the self test method described above, the user can scale sensor
*/
int calibrate()
{
struct mag_report report;
ssize_t sz;
int ret;
int fd = open(MAG_DEVICE_PATH, O_RDONLY);
if (fd < 0)
err(1, "%s open failed (try 'hmc5883 start' if the driver is not running", MAG_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("measurement: %.6f %.6f %.6f", (double)report.x, (double)report.y, (double)report.z);
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 10 Hz */
if (OK != ioctl(fd, SENSORIOCSPOLLRATE, 10))
errx(1, "failed to set 2Hz poll rate");
/* Set to 2.5 Gauss */
if (OK != ioctl(fd, MAGIOCSRANGE, 2)) {
warnx("failed to set 2.5 Ga range");
}
if (OK != ioctl(fd, MAGIOCCALIBRATE, 1)) {
warnx("failed to enable sensor calibration mode");
}
struct mag_scale mscale_null = {
0.0f,
1.0f,
0.0f,
1.0f,
0.0f,
1.0f,
};
if (OK != ioctl(fd, MAGIOCSSCALE, (long unsigned int)&mscale_null)) {
warn("WARNING: failed to set null scale / offsets for mag");
}
float avg_excited[3];
unsigned i;
/* read the sensor 10x and report each value */
for (i = 0; i < 10; 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");
} else {
avg_excited[0] += report.x;
avg_excited[1] += report.y;
avg_excited[2] += report.z;
}
warnx("periodic read %u", i);
warnx("measurement: %.6f %.6f %.6f", (double)report.x, (double)report.y, (double)report.z);
warnx("time: %lld", report.timestamp);
}
// warnx("starting calibration");
// struct mag_report report;
// ssize_t sz;
// int ret;
// int fd = open(MAG_DEVICE_PATH, O_RDONLY);
// if (fd < 0)
// err(1, "%s open failed (try 'hmc5883 start' if the driver is not running", MAG_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("measurement: %.6f %.6f %.6f", (double)report.x, (double)report.y, (double)report.z);
// warnx("time: %lld", report.timestamp);
// /* get scaling, set to zero */
// struct mag_scale mscale_previous;
// if (OK != ioctl(fd, MAGIOCGSCALE, (long unsigned int)&mscale_previous)) {
// warn("WARNING: failed to get scale / offsets for mag");
// }
// struct mag_scale mscale_null = {
// 0.0f,
// 1.0f,
// 0.0f,
// 1.0f,
// 0.0f,
// 1.0f,
// };
// if (OK != ioctl(fd, MAGIOCSSCALE, (long unsigned int)&mscale_null)) {
// warn("WARNING: failed to set null scale / offsets for mag");
// }
// warnx("sensor ready");
// float avg_excited[3] = {0.0f, 0.0f, 0.0f};
// if (OK != ioctl(fd, MAGIOCCALIBRATE, 1)) {
// warnx("failed to enable sensor calibration mode");
// }
// /* Set to 2.5 Gauss */
// if (OK != ioctl(fd, MAGIOCSRANGE, 2)) {
// warnx("failed to set 2.5 Ga range");
// }
// /* set the queue depth to 10 */
// if (OK != ioctl(fd, SENSORIOCSQUEUEDEPTH, 10)) {
// warnx("failed to set queue depth");
// return 1;
// } else {
// warnx("set queue depth");
// }
// /* start the sensor polling at 100Hz */
// if (OK != ioctl(fd, SENSORIOCSPOLLRATE, 100)) {
// warnx("failed to set 100 Hz poll rate");
// return 1;
// } else {
// warnx("set 100 Hz poll rate");
// }
// int i;
// for (i = 0; i < 10; i++) {
// struct pollfd fds;
// (void) ioctl(fd, MAGIOCCALIBRATE, 1);
// /* wait for data to be ready */
// fds.fd = fd;
// fds.events = POLLIN;
// ret = poll(&fds, 1, 2000);
// if (ret != 1) {
// warnx("timed out waiting for sensor data");
// return 1;
// }
// /* now go get it */
// sz = read(fd, &report, sizeof(report));
// if (sz != sizeof(report)) {
// warn("periodic read failed");
// return 1;
// } else {
// avg_excited[0] += report.x;
// avg_excited[1] += report.y;
// avg_excited[2] += report.z;
// }
// warnx("excited read %u", i);
// warnx("measurement: %.6f %.6f %.6f", (double)report.x, (double)report.y, (double)report.z);
// warnx("time: %lld", report.timestamp);
// }
avg_excited[0] /= i;
avg_excited[1] /= i;
avg_excited[2] /= i;
warnx("periodic excited reads %u", i);
warnx("measurement avg: %.6f %.6f %.6f", (double)avg_excited[0], (double)avg_excited[1], (double)avg_excited[2]);
/* Set to 1.1 Gauss and end calibration */
ret = ioctl(fd, MAGIOCCALIBRATE, 0);
ret = ioctl(fd, MAGIOCSRANGE, 1);
float scaling[3];
/* calculate axis scaling */
scaling[0] = 1.16f / avg_excited[0];
/* second axis inverted */
scaling[1] = 1.16f / -avg_excited[1];
scaling[2] = 1.08f / avg_excited[2];
warnx("axes scaling: %.6f %.6f %.6f", (double)scaling[0], (double)scaling[1], (double)scaling[2]);
/* set back to normal mode */
/* Set to 1.1 Gauss */
if (OK != ioctl(fd, MAGIOCSRANGE, 1)) {
warnx("failed to set 1.1 Ga range");
}
if (OK != ioctl(fd, MAGIOCCALIBRATE, 0)) {
warnx("failed to disable sensor calibration mode");
}
/* set scaling in device */
// mscale_previous.x_scale = scaling[0];
// mscale_previous.y_scale = scaling[1];
// mscale_previous.z_scale = scaling[2];
// if (OK != ioctl(fd, MAGIOCSSCALE, (long unsigned int)&mscale_previous)) {
// warn("WARNING: failed to set new scale / offsets for mag");
// }
errx(0, "PASS");
}
/**
* Reset the driver.
*/
void
reset()
{
int fd = open(MAG_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);
}
} // namespace
int
hmc5883_main(int argc, char *argv[])
{
/*
* Start/load the driver.
*/
if (!strcmp(argv[1], "start"))
hmc5883::start();
/*
* Test the driver/device.
*/
if (!strcmp(argv[1], "test"))
hmc5883::test();
/*
* Reset the driver.
*/
if (!strcmp(argv[1], "reset"))
hmc5883::reset();
/*
* Print driver information.
*/
if (!strcmp(argv[1], "info") || !strcmp(argv[1], "status"))
hmc5883::info();
/*
* Autocalibrate the scaling
*/
if (!strcmp(argv[1], "calibrate")) {
if (hmc5883::calibrate() == 0) {
errx(0, "calibration successful");
} else {
errx(1, "calibration failed");
}
}
errx(1, "unrecognized command, try 'start', 'test', 'reset' 'calibrate' or 'info'");
}
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