/****************************************************************************
*
* 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 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(1.0f / 1090.0f), /* default range scale from counts to gauss */
_range_ga(0.88f),
_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");
ret = OK;
out:
return ret;
}
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 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:
/* XXX perform auto-calibration */
return -EINVAL;
default:
/* give it to the superclass */
return I2C::ioctl(filp, cmd, arg);
}
}
void
HMC5883::start()
{
/* make sure we are stopped first */
stop();
/* reset the report ring and state machine */
_collect_phase = false;
_oldest_report = _next_report = 0;
/* schedule a cycle to start things */
work_queue(&_work, (worker_t)&HMC5883::cycle_trampoline, this, 1);
}
void
HMC5883::stop()
{
work_cancel(&_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(&_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(&_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 y[2];
uint8_t z[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 */
_reports[_next_report].x_raw = report.y;
_reports[_next_report].y_raw = 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;
_reports[_next_report].y = ((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::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(®, 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();
/**
* 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", report.x, report.y, 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", report.x, report.y, report.z);
warnx("time: %lld", report.timestamp);
}
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"))
hmc5883::info();
errx(1, "unrecognised command, try 'start', 'test', 'reset' or 'info'");
}