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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 -*-
/*
* AP_Compass_HMC5843.cpp - Arduino Library for HMC5843 I2C magnetometer
* Code by Jordi Muñoz and Jose Julio. DIYDrones.com
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* Sensor is conected to I2C port
* Sensor is initialized in Continuos mode (10Hz)
*
*/
// AVR LibC Includes
#include <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
// 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) {
healthy = false;
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) {
healthy = false;
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) {
if (healthy) {
hal.i2c->setHighSpeed(false);
}
healthy = false;
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)
{
uint32_t tnow = hal.scheduler->micros();
if (healthy && _accum_count != 0 && (tnow - _last_accum_time) < 13333) {
// the compass gets new data at 75Hz
return;
}
if (read_raw()) {
// 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->delay(10);
// determine if we are using 5843 or 5883L
if (!write_register(ConfigRegA, SampleAveraging_8<<5 | DataOutputRate_75HZ<<2 | NormalOperation) ||
!read_register(ConfigRegA, &_base_config)) {
healthy = false;
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;
expected_x = 766;
expected_yz = 713;
gain_multiple = 660.0 / 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
return false;
}
calibration[0] = 0;
calibration[1] = 0;
calibration[2] = 0;
while ( success == 0 && numAttempts < 20 && 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];
cal[0] = fabs(expected_x / (float)_mag_x);
cal[1] = fabs(expected_yz / (float)_mag_y);
cal[2] = fabs(expected_yz / (float)_mag_z);
if (cal[0] > 0.7 && cal[0] < 1.3 &&
cal[1] > 0.7 && cal[1] < 1.3 &&
cal[2] > 0.7 && cal[2] < 1.3) {
good_count++;
calibration[0] += cal[0];
calibration[1] += cal[1];
calibration[2] += cal[2];
}
#if 0
/* useful for debugging */
Serial.print("mag_x: ");
Serial.print(_mag_x);
Serial.print(" mag_y: ");
Serial.print(_mag_y);
Serial.print(" mag_z: ");
Serial.println(_mag_z);
Serial.print("CalX: ");
Serial.print(calibration[0]/good_count);
Serial.print(" CalY: ");
Serial.print(calibration[1]/good_count);
Serial.print(" CalZ: ");
Serial.println(calibration[2]/good_count);
#endif
}
if (good_count >= 5) {
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()) {
return false;
}
_initialised = true;
// perform an initial read
healthy = true;
read();
return success;
}
// Read Sensor data
bool 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 false;
}
if (!healthy) {
if (hal.scheduler->millis() < _retry_time) {
return false;
}
if (!re_initialise()) {
_retry_time = hal.scheduler->millis() + 1000;
hal.i2c->setHighSpeed(false);
return false;
}
}
if (_accum_count == 0) {
accumulate();
if (!healthy || _accum_count == 0) {
// try again in 1 second, and set I2c clock speed slower
_retry_time = hal.scheduler->millis() + 1000;
hal.i2c->setHighSpeed(false);
return false;
}
}
mag_x = _mag_x_accum * calibration[0] / _accum_count;
mag_y = _mag_y_accum * calibration[1] / _accum_count;
mag_z = _mag_z_accum * calibration[2] / _accum_count;
_accum_count = 0;
_mag_x_accum = _mag_y_accum = _mag_z_accum = 0;
last_update = hal.scheduler->micros(); // record time of update
// rotate to the desired orientation
Vector3f rot_mag = Vector3f(mag_x,mag_y,mag_z);
if (product_id == AP_COMPASS_TYPE_HMC5883L) {
rot_mag.rotate(ROTATION_YAW_90);
}
rot_mag.rotate(_orientation);
rot_mag += _offset.get();
mag_x = rot_mag.x;
mag_y = rot_mag.y;
mag_z = rot_mag.z;
healthy = true;
return true;
}
// set orientation
void
AP_Compass_HMC5843::set_orientation(enum Rotation rotation)
{
_orientation = rotation;
}
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