search

adafruit / Adafruit_BMP280_Library

Arduino Library for BMP280 sensors
250 stars 187 forks source link

Pa or hPa? #35

Closed bleckers closed 4 years ago

bleckers commented 4 years ago

In the library cpp file, the code states:

/*!
 * Reads the barometric pressure from the device.
 * @return Barometric pressure in hPa.
 */
float Adafruit_BMP280::readPressure() {

However in the example it states:

    Serial.print(F("Pressure = "));
    Serial.print(bmp.readPressure());
    Serial.println(" Pa");

Are these libraries returning Pa or hPa?

bleckers commented 4 years ago

Getting values of 101631.3 leads me to believe this library returns Pa, unless we are on Venus or something?

ladyada commented 4 years ago

yes it returns Pa, if you submit a PR for the doc fix, we'll merge!

bleckers commented 4 years ago

Done! Thank you :D

ladyada commented 4 years ago

you have to PR it next

kevinjwalters commented 4 years ago

This is inconsistent with the specification/guidelines on https://learn.adafruit.com/using-the-adafruit-unified-sensor-driver/how-does-it-work#standardised-si-units-for-sensor-data-2-2 which states hPa (hecto-Pascals). I noticed this on the video for CLUE: https://www.youtube.com/watch?v=Nz38vF2W8BI&t=11s (look closely at values on y axis)

ladyada commented 4 years ago

readPressure() is Pa, but the Unified sensor example (sensortest) is in hPa