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ardupilot/libraries/AP_Compass/AP_Compass_HMC5843.cpp

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/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
/*
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*
* AP_Compass_HMC5843.cpp - Arduino Library for HMC5843 I2C magnetometer
* Code by Jordi Muñoz and Jose Julio. DIYDrones.com
*
* Sensor is conected to I2C port
* Sensor is initialized in Continuos mode (10Hz)
*
*/
// AVR LibC Includes
#include <AP_Math.h>
#include <AP_HAL.h>
#include "AP_Compass_HMC5843.h"
extern const AP_HAL::HAL& hal;
#define COMPASS_ADDRESS 0x1E
#define ConfigRegA 0x00
#define ConfigRegB 0x01
#define magGain 0x20
#define PositiveBiasConfig 0x11
#define NegativeBiasConfig 0x12
#define NormalOperation 0x10
#define ModeRegister 0x02
#define ContinuousConversion 0x00
#define SingleConversion 0x01
// ConfigRegA valid sample averaging for 5883L
#define SampleAveraging_1 0x00
#define SampleAveraging_2 0x01
#define SampleAveraging_4 0x02
#define SampleAveraging_8 0x03
// ConfigRegA valid data output rates for 5883L
#define DataOutputRate_0_75HZ 0x00
#define DataOutputRate_1_5HZ 0x01
#define DataOutputRate_3HZ 0x02
#define DataOutputRate_7_5HZ 0x03
#define DataOutputRate_15HZ 0x04
#define DataOutputRate_30HZ 0x05
#define DataOutputRate_75HZ 0x06
// constructor
AP_Compass_HMC5843::AP_Compass_HMC5843(Compass &compass):
AP_Compass_Backend(compass),
_retry_time(0),
_i2c_sem(NULL),
_mag_x(0),
_mag_y(0),
_mag_z(0),
_mag_x_accum(0),
_mag_y_accum(0),
_mag_z_accum(0),
_accum_count(0),
_last_accum_time(0),
_compass_instance(0),
_product_id(0)
{}
// detect the sensor
AP_Compass_Backend *AP_Compass_HMC5843::detect(Compass &compass)
{
AP_Compass_HMC5843 *sensor = new AP_Compass_HMC5843(compass);
if (sensor == NULL) {
return NULL;
}
if (!sensor->init()) {
delete sensor;
return NULL;
}
return sensor;
}
// read_register - read a register value
bool AP_Compass_HMC5843::read_register(uint8_t address, uint8_t *value)
{
if (hal.i2c->readRegister((uint8_t)COMPASS_ADDRESS, address, value) != 0) {
_retry_time = hal.scheduler->millis() + 1000;
return false;
}
return true;
}
// write_register - update a register value
bool AP_Compass_HMC5843::write_register(uint8_t address, uint8_t value)
{
if (hal.i2c->writeRegister((uint8_t)COMPASS_ADDRESS, address, value) != 0) {
_retry_time = hal.scheduler->millis() + 1000;
return false;
}
return true;
}
// Read Sensor data
bool AP_Compass_HMC5843::read_raw()
{
uint8_t buff[6];
if (hal.i2c->readRegisters(COMPASS_ADDRESS, 0x03, 6, buff) != 0) {
hal.i2c->setHighSpeed(false);
_retry_time = hal.scheduler->millis() + 1000;
return false;
}
int16_t rx, ry, rz;
rx = (((int16_t)buff[0]) << 8) | buff[1];
if (_product_id == AP_COMPASS_TYPE_HMC5883L) {
rz = (((int16_t)buff[2]) << 8) | buff[3];
ry = (((int16_t)buff[4]) << 8) | buff[5];
} else {
ry = (((int16_t)buff[2]) << 8) | buff[3];
rz = (((int16_t)buff[4]) << 8) | buff[5];
}
if (rx == -4096 || ry == -4096 || rz == -4096) {
// no valid data available
return false;
}
_mag_x = -rx;
_mag_y = ry;
_mag_z = -rz;
return true;
}
// accumulate a reading from the magnetometer
void AP_Compass_HMC5843::accumulate(void)
{
if (!_initialised) {
// someone has tried to enable a compass for the first time
// mid-flight .... we can't do that yet (especially as we won't
// have the right orientation!)
return;
}
uint32_t tnow = hal.scheduler->micros();
if (_accum_count != 0 && (tnow - _last_accum_time) < 13333) {
// the compass gets new data at 75Hz
return;
}
if (!_i2c_sem->take(1)) {
// the bus is busy - try again later
return;
}
bool result = read_raw();
_i2c_sem->give();
if (result) {
// the _mag_N values are in the range -2048 to 2047, so we can
// accumulate up to 15 of them in an int16_t. Let's make it 14
// for ease of calculation. We expect to do reads at 10Hz, and
// we get new data at most 75Hz, so we don't expect to
// accumulate more than 8 before a read
_mag_x_accum += _mag_x;
_mag_y_accum += _mag_y;
_mag_z_accum += _mag_z;
_accum_count++;
if (_accum_count == 14) {
_mag_x_accum /= 2;
_mag_y_accum /= 2;
_mag_z_accum /= 2;
_accum_count = 7;
}
_last_accum_time = tnow;
}
}
/*
* re-initialise after a IO error
*/
bool AP_Compass_HMC5843::re_initialise()
{
if (!write_register(ConfigRegA, _base_config) ||
!write_register(ConfigRegB, magGain) ||
!write_register(ModeRegister, ContinuousConversion))
return false;
return true;
}
// Public Methods //////////////////////////////////////////////////////////////
bool
AP_Compass_HMC5843::init()
{
int numAttempts = 0, good_count = 0;
bool success = false;
uint8_t calibration_gain = 0x20;
uint16_t expected_x = 715;
uint16_t expected_yz = 715;
float gain_multiple = 1.0;
hal.scheduler->suspend_timer_procs();
hal.scheduler->delay(10);
_i2c_sem = hal.i2c->get_semaphore();
if (!_i2c_sem->take(HAL_SEMAPHORE_BLOCK_FOREVER)) {
hal.scheduler->panic(PSTR("Failed to get HMC5843 semaphore"));
}
// determine if we are using 5843 or 5883L
_base_config = 0;
if (!write_register(ConfigRegA, SampleAveraging_8<<5 | DataOutputRate_75HZ<<2 | NormalOperation) ||
!read_register(ConfigRegA, &_base_config)) {
_i2c_sem->give();
hal.scheduler->resume_timer_procs();
return false;
}
if ( _base_config == (SampleAveraging_8<<5 | DataOutputRate_75HZ<<2 | NormalOperation)) {
// a 5883L supports the sample averaging config
_product_id = AP_COMPASS_TYPE_HMC5883L;
calibration_gain = 0x60;
/*
note that the HMC5883 datasheet gives the x and y expected
values as 766 and the z as 713. Experiments have shown the x
axis is around 766, and the y and z closer to 713.
*/
expected_x = 766;
expected_yz = 713;
gain_multiple = 660.0f / 1090; // adjustment for runtime vs calibration gain
} else if (_base_config == (NormalOperation | DataOutputRate_75HZ<<2)) {
_product_id = AP_COMPASS_TYPE_HMC5843;
} else {
// not behaving like either supported compass type
_i2c_sem->give();
hal.scheduler->resume_timer_procs();
return false;
}
calibration[0] = 0;
calibration[1] = 0;
calibration[2] = 0;
while ( success == 0 && numAttempts < 25 && good_count < 5)
{
// record number of attempts at initialisation
numAttempts++;
// force positiveBias (compass should return 715 for all channels)
if (!write_register(ConfigRegA, PositiveBiasConfig))
continue; // compass not responding on the bus
hal.scheduler->delay(50);
// set gains
if (!write_register(ConfigRegB, calibration_gain) ||
!write_register(ModeRegister, SingleConversion))
continue;
// read values from the compass
hal.scheduler->delay(50);
if (!read_raw())
continue; // we didn't read valid values
hal.scheduler->delay(10);
float cal[3];
// hal.console->printf_P(PSTR("mag %d %d %d\n"), _mag_x, _mag_y, _mag_z);
cal[0] = fabsf(expected_x / (float)_mag_x);
cal[1] = fabsf(expected_yz / (float)_mag_y);
cal[2] = fabsf(expected_yz / (float)_mag_z);
// hal.console->printf_P(PSTR("cal=%.2f %.2f %.2f\n"), cal[0], cal[1], cal[2]);
// we throw away the first two samples as the compass may
// still be changing its state from the application of the
// strap excitation. After that we accept values in a
// reasonable range
if (numAttempts > 2 &&
cal[0] > 0.7f && cal[0] < 1.35f &&
cal[1] > 0.7f && cal[1] < 1.35f &&
cal[2] > 0.7f && cal[2] < 1.35f) {
// hal.console->printf_P(PSTR("cal=%.2f %.2f %.2f good\n"), cal[0], cal[1], cal[2]);
good_count++;
calibration[0] += cal[0];
calibration[1] += cal[1];
calibration[2] += cal[2];
}
#if 0
/* useful for debugging */
hal.console->printf_P(PSTR("MagX: %d MagY: %d MagZ: %d\n"), (int)_mag_x, (int)_mag_y, (int)_mag_z);
hal.console->printf_P(PSTR("CalX: %.2f CalY: %.2f CalZ: %.2f\n"), cal[0], cal[1], cal[2]);
#endif
}
if (good_count >= 5) {
/*
The use of gain_multiple below is incorrect, as the gain
difference between 2.5Ga mode and 1Ga mode is already taken
into account by the expected_x and expected_yz values. We
are not going to fix it however as it would mean all
APM1/APM2 users redoing their compass calibration. The
impact is that the values we report on APM1/APM2 are lower
than they should be (by a multiple of about 0.6). This
doesn't have any impact other than the learned compass
offsets
*/
calibration[0] = calibration[0] * gain_multiple / good_count;
calibration[1] = calibration[1] * gain_multiple / good_count;
calibration[2] = calibration[2] * gain_multiple / good_count;
success = true;
} else {
/* best guess */
calibration[0] = 1.0;
calibration[1] = 1.0;
calibration[2] = 1.0;
}
// leave test mode
if (!re_initialise()) {
_i2c_sem->give();
hal.scheduler->resume_timer_procs();
return false;
}
_i2c_sem->give();
hal.scheduler->resume_timer_procs();
_initialised = true;
// perform an initial read
read();
#if 0
hal.console->printf_P(PSTR("CalX: %.2f CalY: %.2f CalZ: %.2f\n"),
calibration[0], calibration[1], calibration[2]);
#endif
if (success) {
// register the compass instance in the frontend
_compass_instance = register_compass();
set_dev_id(_compass_instance, _product_id);
}
return success;
}
// Read Sensor data
void AP_Compass_HMC5843::read()
{
if (!_initialised) {
// someone has tried to enable a compass for the first time
// mid-flight .... we can't do that yet (especially as we won't
// have the right orientation!)
return;
}
if (_retry_time != 0) {
if (hal.scheduler->millis() < _retry_time) {
return;
}
if (!re_initialise()) {
_retry_time = hal.scheduler->millis() + 1000;
hal.i2c->setHighSpeed(false);
return;
}
}
if (_accum_count == 0) {
accumulate();
if (_retry_time != 0) {
hal.i2c->setHighSpeed(false);
return;
}
}
Vector3f field(_mag_x_accum * calibration[0],
_mag_y_accum * calibration[1],
_mag_z_accum * calibration[2]);
field /= _accum_count;
_accum_count = 0;
_mag_x_accum = _mag_y_accum = _mag_z_accum = 0;
// rotate to the desired orientation
if (_product_id == AP_COMPASS_TYPE_HMC5883L) {
field.rotate(ROTATION_YAW_90);
}
publish_field(field, _compass_instance);
_retry_time = 0;
}
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