altitude property

Author: FoamyGuy

adafruit_bmp5xx.py

@@ -228,6 +228,7 @@ def __init__(self, i2c: I2C, address: int = DEFAULT_ADAFRUIT_ADDR) -> None:
         except ValueError:
             raise ValueError(f"No I2C device found at address 0x{address:02X}")
 
+        self.sea_level_pressure = 1013.25
         self.reset()
         time.sleep(0.0025)
 
@@ -261,6 +262,12 @@ def pressure(self) -> float:
         raw_p = self._pressure
         return raw_p / 64.0 / 100.0  # Convert raw_data->Pa->hPa
 
+    @property
+    def altitude(self) -> float:
+        """The altitude in meters based on the currently set sea level pressure."""
+        # see https://www.weather.gov/media/epz/wxcalc/pressureAltitude.pdf
+        return 44307.7 * (1 - (self.pressure / self.sea_level_pressure) ** 0.190284)
+
     def reset(self) -> None:
         """Reset the BMP5xx device."""
         self.command = BMP5_SOFT_RESET_CMD

examples/bmp5xx_simpletest.py

@@ -7,11 +7,19 @@
 
 from adafruit_bmp5xx import BMP5XX
 
+SEALEVELPRESSURE_HPA = 1013.25
+
 i2c = board.STEMMA_I2C()
 bmp = BMP5XX(i2c)
 start_time = time.monotonic()
 
+bmp.sea_level_pressure = SEALEVELPRESSURE_HPA
+
 while True:
     if bmp.data_ready:
-        print(f"temp F: {bmp.temperature * (9 / 5) + 32} pressure: {bmp.pressure} hPa")
+        print(
+            f"temp F: {bmp.temperature * (9 / 5) + 32} "
+            f"pressure: {bmp.pressure} hPa "
+            f"Approx altitude: {bmp.altitude} m"
+        )
         time.sleep(1)