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AP_Compass: HMC5843: fix _calibrate()

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The use of _gain_multiple is not necessary because the values of
expected_{x,yz} and _mag_{x,y,z} are both in sensor raw unit (i.e., lsbs).

That wasn't fixed before in order not to make APM users to recalibrate their
compasses.
This commit is contained in:
Gustavo Jose de Sousa 2015-09-29 11:48:46 -03:00 committed by Randy Mackay
parent 88a1a928e9
commit 814442563e
2 changed files with 6 additions and 15 deletions
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17
libraries/AP_Compass/AP_Compass_HMC5843.cpp
View File

@ -417,20 +417,9 @@ bool AP_Compass_HMC5843::_calibrate(uint8_t calibration_gain,
}
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
*/
_scaling[0] = _scaling[0] * _gain_multiple / good_count;
_scaling[1] = _scaling[1] * _gain_multiple / good_count;
_scaling[2] = _scaling[2] * _gain_multiple / good_count;
_scaling[0] = _scaling[0] / good_count;
_scaling[1] = _scaling[1] / good_count;
_scaling[2] = _scaling[2] / good_count;
success = true;
} else {
/* best guess */

4
libraries/AP_Compass/AP_Compass_HMC5843.h
View File

@ -31,7 +31,9 @@ private:
bool read_register(uint8_t address, uint8_t *value);
bool write_register(uint8_t address, uint8_t value);
bool _calibrate(uint8_t calibration_gain, uint16_t expected_x, uint16_t expected_yz);
bool _calibrate(uint8_t calibration_gain,
uint16_t expected_x,
uint16_t expected_yz);
bool _detect_version();
uint32_t _retry_time; // when unhealthy the millis() value to retry at