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hmc5883.cpp
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hmc5883.cpp
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/****************************************************************************
*
* Copyright (c) 2012-2015 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 / HMC5983 magnetometer connected via I2C or SPI.
*/
#include <px4_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 <board_config.h>
#include <systemlib/perf_counter.h>
#include <systemlib/err.h>
#include <drivers/drv_mag.h>
#include <drivers/drv_hrt.h>
#include <drivers/device/ringbuffer.h>
#include <drivers/drv_device.h>
#include <uORB/uORB.h>
#include <float.h>
#include <getopt.h>
#include <lib/conversion/rotation.h>
#include "hmc5883.h"
/*
* HMC5883 internal constants and data structures.
*/
/* Max measurement rate is 160Hz, however with 160 it will be set to 166 Hz, therefore workaround using 150 */
#define HMC5883_CONVERSION_INTERVAL (1000000 / 150) /* 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
/* temperature on hmc5983 only */
#define ADDR_TEMP_OUT_MSB 0x31
#define ADDR_TEMP_OUT_LSB 0x32
/* 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 HMC5983_TEMP_SENSOR_ENABLE (1 << 7)
enum HMC5883_BUS {
HMC5883_BUS_ALL = 0,
HMC5883_BUS_I2C_INTERNAL,
HMC5883_BUS_I2C_EXTERNAL,
HMC5883_BUS_SPI
};
/* 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
class HMC5883 : public device::CDev
{
public:
HMC5883(device::Device *interface, const char *path, enum Rotation rotation);
virtual ~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:
Device *_interface;
private:
work_s _work;
unsigned _measure_ticks;
ringbuffer::RingBuffer *_reports;
struct mag_calibration_s _scale;
float _range_scale;
float _range_ga;
bool _collect_phase;
int _class_instance;
int _orb_class_instance;
orb_advert_t _mag_topic;
perf_counter_t _sample_perf;
perf_counter_t _comms_errors;
perf_counter_t _buffer_overflows;
perf_counter_t _range_errors;
perf_counter_t _conf_errors;
/* status reporting */
bool _sensor_ok; /**< sensor was found and reports ok */
bool _calibrated; /**< the calibration is valid */
enum Rotation _rotation;
struct mag_report _last_report; /**< used for info() */
uint8_t _range_bits;
uint8_t _conf_reg;
uint8_t _temperature_counter;
uint8_t _temperature_error_count;
/**
* 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();
/**
* Reset the device
*/
int reset();
/**
* 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(struct file *filp, unsigned enable);
/**
* 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 positive strap, -1 to enable
* negative strap, 0 to set to normal mode
*/
int set_excitement(unsigned enable);
/**
* enable hmc5983 temperature compensation
*/
int set_temperature_compensation(unsigned enable);
/**
* Set the sensor range.
*
* Sets the internal range to handle at least the argument in Gauss.
*/
int set_range(unsigned range);
/**
* check the sensor range.
*
* checks that the range of the sensor is correctly set, to
* cope with communication errors causing the range to change
*/
void check_range(void);
/**
* check the sensor configuration.
*
* checks that the config of the sensor is correctly set, to
* cope with communication errors causing the configuration to
* change
*/
void check_conf(void);
/**
* 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]);
/**
* Check the current calibration and update device status
*
* @return 0 if calibration is ok, 1 else
*/
int check_calibration();
/**
* Check the current scale calibration
*
* @return 0 if scale calibration is ok, 1 else
*/
int check_scale();
/**
* Check the current offset calibration
*
* @return 0 if offset calibration is ok, 1 else
*/
int check_offset();
/* this class has pointer data members, do not allow copying it */
HMC5883(const HMC5883 &);
HMC5883 operator=(const HMC5883 &);
};
/*
* Driver 'main' command.
*/
extern "C" __EXPORT int hmc5883_main(int argc, char *argv[]);
HMC5883::HMC5883(device::Device *interface, const char *path, enum Rotation rotation) :
CDev("HMC5883", path),
_interface(interface),
_work{},
_measure_ticks(0),
_reports(nullptr),
_scale{},
_range_scale(0), /* default range scale from counts to gauss */
_range_ga(1.3f),
_collect_phase(false),
_class_instance(-1),
_orb_class_instance(-1),
_mag_topic(nullptr),
_sample_perf(perf_alloc(PC_ELAPSED, "hmc5883_read")),
_comms_errors(perf_alloc(PC_COUNT, "hmc5883_com_err")),
_buffer_overflows(perf_alloc(PC_COUNT, "hmc5883_buf_of")),
_range_errors(perf_alloc(PC_COUNT, "hmc5883_rng_err")),
_conf_errors(perf_alloc(PC_COUNT, "hmc5883_conf_err")),
_sensor_ok(false),
_calibrated(false),
_rotation(rotation),
_last_report{0},
_range_bits(0),
_conf_reg(0),
_temperature_counter(0),
_temperature_error_count(0)
{
_device_id.devid_s.devtype = DRV_MAG_DEVTYPE_HMC5883;
// enable debug() calls
_debug_enabled = false;
// 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();
if (_reports != nullptr) {
delete _reports;
}
if (_class_instance != -1) {
unregister_class_devname(MAG_BASE_DEVICE_PATH, _class_instance);
}
// free perf counters
perf_free(_sample_perf);
perf_free(_comms_errors);
perf_free(_buffer_overflows);
perf_free(_range_errors);
perf_free(_conf_errors);
}
int
HMC5883::init()
{
int ret = ERROR;
ret = CDev::init();
if (ret != OK) {
DEVICE_DEBUG("CDev init failed");
goto out;
}
/* allocate basic report buffers */
_reports = new ringbuffer::RingBuffer(2, sizeof(mag_report));
if (_reports == nullptr) {
goto out;
}
/* reset the device configuration */
reset();
_class_instance = register_class_devname(MAG_BASE_DEVICE_PATH);
ret = OK;
/* sensor is ok, but not calibrated */
_sensor_ok = true;
out:
return ret;
}
int HMC5883::set_range(unsigned range)
{
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 = 0;
ret = read_reg(ADDR_CONF_B, range_bits_in);
if (OK != ret) {
perf_count(_comms_errors);
}
return !(range_bits_in == (_range_bits << 5));
}
/**
check that the range register has the right value. This is done
periodically to cope with I2C bus noise causing the range of the
compass changing.
*/
void HMC5883::check_range(void)
{
int ret;
uint8_t range_bits_in = 0;
ret = read_reg(ADDR_CONF_B, range_bits_in);
if (OK != ret) {
perf_count(_comms_errors);
return;
}
if (range_bits_in != (_range_bits << 5)) {
perf_count(_range_errors);
ret = write_reg(ADDR_CONF_B, (_range_bits << 5));
if (OK != ret) {
perf_count(_comms_errors);
}
}
}
/**
check that the configuration register has the right value. This is
done periodically to cope with I2C bus noise causing the
configuration of the compass to change.
*/
void HMC5883::check_conf(void)
{
int ret;
uint8_t conf_reg_in = 0;
ret = read_reg(ADDR_CONF_A, conf_reg_in);
if (OK != ret) {
perf_count(_comms_errors);
return;
}
if (conf_reg_in != _conf_reg) {
perf_count(_conf_errors);
ret = write_reg(ADDR_CONF_A, _conf_reg);
if (OK != ret) {
perf_count(_comms_errors);
}
}
}
ssize_t
HMC5883::read(struct file *filp, char *buffer, size_t buflen)
{
unsigned count = buflen / sizeof(struct mag_report);
struct mag_report *mag_buf = reinterpret_cast<struct mag_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(mag_buf)) {
ret += sizeof(struct mag_report);
mag_buf++;
}
}
/* 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 {
_reports->flush();
/* 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;
}
if (_reports->get(mag_buf)) {
ret = sizeof(struct mag_report);
}
} while (0);
return ret;
}
int
HMC5883::ioctl(struct file *filp, int cmd, unsigned long arg)
{
unsigned dummy = 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 1000000 / TICK2USEC(_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:
return reset();
case MAGIOCSSAMPLERATE:
/* same as pollrate because device is in single measurement mode*/
return ioctl(filp, SENSORIOCSPOLLRATE, arg);
case MAGIOCGSAMPLERATE:
/* same as pollrate because device is in single measurement mode*/
return 1000000 / TICK2USEC(_measure_ticks);
case MAGIOCSRANGE:
return set_range(arg);
case MAGIOCGRANGE:
return _range_ga;
case MAGIOCSLOWPASS:
case MAGIOCGLOWPASS:
/* not supported, no internal filtering */
return -EINVAL;
case MAGIOCSSCALE:
/* set new scale factors */
memcpy(&_scale, (struct mag_calibration_s *)arg, sizeof(_scale));
/* check calibration, but not actually return an error */
(void)check_calibration();
return 0;
case MAGIOCGSCALE:
/* copy out scale factors */
memcpy((struct mag_calibration_s *)arg, &_scale, sizeof(_scale));
return 0;
case MAGIOCCALIBRATE:
return calibrate(filp, arg);
case MAGIOCEXSTRAP:
return set_excitement(arg);
case MAGIOCSELFTEST:
return check_calibration();
case MAGIOCGEXTERNAL:
DEVICE_DEBUG("MAGIOCGEXTERNAL in main driver");
return _interface->ioctl(cmd, dummy);
case MAGIOCSTEMPCOMP:
return set_temperature_compensation(arg);
case DEVIOCGDEVICEID:
return _interface->ioctl(cmd, dummy);
default:
/* give it to the superclass */
return CDev::ioctl(filp, cmd, arg);
}
}
void
HMC5883::start()
{
/* reset the report ring and state machine */
_collect_phase = false;
_reports->flush();
/* schedule a cycle to start things */
work_queue(HPWORK, &_work, (worker_t)&HMC5883::cycle_trampoline, this, 1);
}
void
HMC5883::stop()
{
work_cancel(HPWORK, &_work);
}
int
HMC5883::reset()
{
/* set range */
return set_range(_range_ga);
}
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()) {
DEVICE_DEBUG("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()) {
DEVICE_DEBUG("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;
uint8_t check_counter;
perf_begin(_sample_perf);
struct mag_report new_report;
bool sensor_is_onboard = false;
float xraw_f;
float yraw_f;
float zraw_f;
/* this should be fairly close to the end of the measurement, so the best approximation of the time */
new_report.timestamp = hrt_absolute_time();
new_report.error_count = perf_event_count(_comms_errors);
/*
* @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 */
ret = _interface->read(ADDR_DATA_OUT_X_MSB, (uint8_t *)&hmc_report, sizeof(hmc_report));
if (ret != OK) {
perf_count(_comms_errors);
DEVICE_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)) {
perf_count(_comms_errors);
goto out;
}
/* get measurements from the device */
new_report.temperature = 0;
if (_conf_reg & HMC5983_TEMP_SENSOR_ENABLE) {
/*
if temperature compensation is enabled read the
temperature too.
We read the temperature every 10 samples to avoid
excessive I2C traffic
*/
if (_temperature_counter++ == 10) {
uint8_t raw_temperature[2];
_temperature_counter = 0;
ret = _interface->read(ADDR_TEMP_OUT_MSB,
raw_temperature, sizeof(raw_temperature));
if (ret == OK) {
int16_t temp16 = (((int16_t)raw_temperature[0]) << 8) +
raw_temperature[1];
new_report.temperature = 25 + (temp16 / (16 * 8.0f));
_temperature_error_count = 0;
} else {
_temperature_error_count++;
if (_temperature_error_count == 10) {
/*
it probably really is an old HMC5883,
and can't do temperature. Disable it
*/
_temperature_error_count = 0;
DEVICE_DEBUG("disabling temperature compensation");
set_temperature_compensation(0);
}
}
} else {
new_report.temperature = _last_report.temperature;
}
}
/*
* RAW outputs
*
* to align the sensor axes with the board, x and y need to be flipped
* and y needs to be negated
*/
new_report.x_raw = report.y;
new_report.y_raw = -report.x;
/* z remains z */
new_report.z_raw = report.z;
/* scale values for output */
// XXX revisit for SPI part, might require a bus type IOCTL
unsigned dummy;
sensor_is_onboard = !_interface->ioctl(MAGIOCGEXTERNAL, dummy);
if (sensor_is_onboard) {
// convert onboard so it matches offboard for the
// scaling below
report.y = -report.y;
report.x = -report.x;
}