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fix(ms5611): correct timestamp_sample to integration midpoint

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The MS5611 ADC conversion at OSR 1024 takes ~2.28ms, but the data is
read after a 10ms scheduling delay. The current code timestamps the
read time, which is ~8.9ms after the true integration midpoint.
Correct timestamp_sample by subtracting the full offset
(CONVERSION_INTERVAL - CONVERSION_TIME/2) from the read time.
This commit is contained in:
Jacob Dahl 2026-03-31 14:48:26 -08:00 committed by Jacob Dahl
parent 8170e113fd
commit c149bad4f2
2 changed files with 8 additions and 2 deletions
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1
src/drivers/barometer/ms5611/MS5611.hpp
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@ -83,6 +83,7 @@ enum MS56XX_DEVICE_TYPES {
* conversion finished
*/
#define MS5611_CONVERSION_INTERVAL 10000 /* microseconds */
#define MS5611_OSR1024_CONVERSION_TIME 2280 /* max ADC conversion time at OSR 1024, microseconds */
#define MS5611_MEASUREMENT_RATIO 3 /* pressure measurements per temperature measurement */
class MS5611 : public I2CSPIDriver<MS5611>

9
src/drivers/barometer/ms5611/ms5611.cpp
View File

@ -243,8 +243,13 @@ MS5611::collect()
perf_begin(_sample_perf);
/* read the most recent measurement - read offset/size are hardcoded in the interface */
const hrt_abstime timestamp_sample = hrt_absolute_time();
/* Correct for measurement integration delay: the conversion was
* started CONVERSION_INTERVAL ago and took OSR1024_CONVERSION_TIME
* to integrate, so the effective sample midpoint is
* (CONVERSION_INTERVAL - OSR1024_CONVERSION_TIME/2) before now. */
const hrt_abstime now = hrt_absolute_time();
static constexpr hrt_abstime correction = MS5611_CONVERSION_INTERVAL - MS5611_OSR1024_CONVERSION_TIME / 2;
const hrt_abstime timestamp_sample = (now > correction) ? (now - correction) : now;
int ret = _interface->read(0, (void *)&raw, 0);
if (ret < 0) {