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Fixed BME680 loss of precision int math error in pressure/altitude measurements

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BME680.pressure / 100 was integer division before being passed onward resulting
in loss of sensor resoluiton for both altitude and pressure changes.

- Changed to float math to fix the value only moving in 1hPa steps
- Pressure/altitude should no longer appear "stuck" waiting to jump
  the next 1hPa change
- Tested on RAK19003+BME680

It looks like BME280, BMP280, etc. should not be affected as their
readPressure() is a float. BMP085 may have a similar problem, but
I do not have one to test with.
This commit is contained in:
Nick Dunklee 2026-03-24 15:16:28 -06:00
parent 8637a749f7
commit 96f8786538
1 changed files with 5 additions and 2 deletions
Download patch file Download diff file Expand all files Collapse all files

7
src/helpers/sensors/EnvironmentSensorManager.cpp
View file

@ -357,8 +357,11 @@ bool EnvironmentSensorManager::querySensors(uint8_t requester_permissions, Cayen
if (BME680.performReading()) {
telemetry.addTemperature(TELEM_CHANNEL_SELF, BME680.temperature);
telemetry.addRelativeHumidity(TELEM_CHANNEL_SELF, BME680.humidity);
telemetry.addBarometricPressure(TELEM_CHANNEL_SELF, BME680.pressure / 100);
telemetry.addAltitude(TELEM_CHANNEL_SELF, 44330.0 * (1.0 - pow((BME680.pressure / 100) / TELEM_BME680_SEALEVELPRESSURE_HPA, 0.1903)));
// pressure is uint32_t Pa — use float division so hPa/altitude are not truncated to whole hPa
const float pressure_hpa = BME680.pressure / 100.0f;
telemetry.addBarometricPressure(TELEM_CHANNEL_SELF, pressure_hpa);
telemetry.addAltitude(TELEM_CHANNEL_SELF,
44330.0f * (1.0f - powf(pressure_hpa / (float)TELEM_BME680_SEALEVELPRESSURE_HPA, 0.1903f)));
telemetry.addAnalogInput(next_available_channel, BME680.gas_resistance);
next_available_channel++;
}