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AP_Baro: MS5611: reduce OSR to 1024 

This is the same change as done in PX4:

	This reduces self-heating of the sensor which reduces the amount
	of altitude change when warming up. Apparently some individual
	sensors are severely affected by this.

	Unfortunately it raises the noise level, but Paul is confident
	it won't be a significant issue.
This commit is contained in:
Lucas De Marchi 2015-11-09 19:25:42 -02:00 committed by Andrew Tridgell
parent ea5cd99651
commit 94d01934f7
1 changed files with 26 additions and 8 deletions
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34
libraries/AP_Baro/AP_Baro_MS5611.cpp
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@ -34,8 +34,26 @@ extern const AP_HAL::HAL& hal;
#define CMD_MS5611_PROM_C5 0xAA #define CMD_MS5611_PROM_C5 0xAA
#define CMD_MS5611_PROM_C6 0xAC #define CMD_MS5611_PROM_C6 0xAC
#define CMD_MS5611_PROM_CRC 0xAE #define CMD_MS5611_PROM_CRC 0xAE
#define CMD_CONVERT_D1_OSR4096 0x48 // Maximum resolution (oversampling)
#define CMD_CONVERT_D2_OSR4096 0x58 // Maximum resolution (oversampling) #define ADDR_CMD_CONVERT_D1_OSR256 0x40 /* write to this address to start pressure conversion */
#define ADDR_CMD_CONVERT_D1_OSR512 0x42 /* write to this address to start pressure conversion */
#define ADDR_CMD_CONVERT_D1_OSR1024 0x44 /* write to this address to start pressure conversion */
#define ADDR_CMD_CONVERT_D1_OSR2048 0x46 /* write to this address to start pressure conversion */
#define ADDR_CMD_CONVERT_D1_OSR4096 0x48 /* write to this address to start pressure conversion */
#define ADDR_CMD_CONVERT_D2_OSR256 0x50 /* write to this address to start temperature conversion */
#define ADDR_CMD_CONVERT_D2_OSR512 0x52 /* write to this address to start temperature conversion */
#define ADDR_CMD_CONVERT_D2_OSR1024 0x54 /* write to this address to start temperature conversion */
#define ADDR_CMD_CONVERT_D2_OSR2048 0x56 /* write to this address to start temperature conversion */
#define ADDR_CMD_CONVERT_D2_OSR4096 0x58 /* write to this address to start temperature conversion */
/*
use an OSR of 1024 to reduce the self-heating effect of the
sensor. Information from MS tells us that some individual sensors
are quite sensitive to this effect and that reducing the OSR can
make a big difference
*/
#define ADDR_CMD_CONVERT_D1 ADDR_CMD_CONVERT_D1_OSR1024
#define ADDR_CMD_CONVERT_D2 ADDR_CMD_CONVERT_D2_OSR1024
// SPI Device ////////////////////////////////////////////////////////////////// // SPI Device //////////////////////////////////////////////////////////////////
@ -194,7 +212,7 @@ AP_Baro_MS56XX::AP_Baro_MS56XX(AP_Baro &baro, AP_SerialBus *serial, bool use_tim
} }
// Send a command to read Temp first // Send a command to read Temp first
_serial->write(CMD_CONVERT_D2_OSR4096); _serial->write(ADDR_CMD_CONVERT_D2);
_last_timer = hal.scheduler->micros(); _last_timer = hal.scheduler->micros();
_state = 0; _state = 0;
@ -290,13 +308,13 @@ void AP_Baro_MS56XX::_timer(void)
_d2_count = 16; _d2_count = 16;
} }
if (_serial->write(CMD_CONVERT_D1_OSR4096)) { // Command to read pressure if (_serial->write(ADDR_CMD_CONVERT_D1)) { // Command to read pressure
_state++; _state++;
} }
} else { } else {
/* if read fails, re-initiate a temperature read command or we are /* if read fails, re-initiate a temperature read command or we are
* stuck */ * stuck */
_serial->write(CMD_CONVERT_D2_OSR4096); _serial->write(ADDR_CMD_CONVERT_D2);
} }
} else { } else {
uint32_t d1 = _serial->read_24bits(0);; uint32_t d1 = _serial->read_24bits(0);;
@ -316,18 +334,18 @@ void AP_Baro_MS56XX::_timer(void)
_updated = true; _updated = true;
if (_state == 4) { if (_state == 4) {
if (_serial->write(CMD_CONVERT_D2_OSR4096)) { // Command to read temperature if (_serial->write(ADDR_CMD_CONVERT_D2)) { // Command to read temperature
_state = 0; _state = 0;
} }
} else { } else {
if (_serial->write(CMD_CONVERT_D1_OSR4096)) { // Command to read pressure if (_serial->write(ADDR_CMD_CONVERT_D1)) { // Command to read pressure
_state++; _state++;
} }
} }
} else { } else {
/* if read fails, re-initiate a pressure read command or we are /* if read fails, re-initiate a pressure read command or we are
* stuck */ * stuck */
_serial->write(CMD_CONVERT_D1_OSR4096); _serial->write(ADDR_CMD_CONVERT_D1);
} }
} }