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Ligne 144 :
Ligne 144 : − + − # Use that value as baseline (don't hesitate to multiply it by 100) + − + − − When you have to "correction" value you don't have to care anymore about the baseline.+ + + + + + + + + + + + + + + + − Indeed, we can read the current pressure (without caring about the baseline) THEN we add the "correction" value --> Tadaaa! We have the SLP pressure (the same than displayed on Reference Weather Station). Ligne 158 :
Ligne 171 : − where {{fname|p}} would contains pressure normalized at sea level (so the SLP value). − The downside of the "mean pressure value" approach (101325 Pa) is that you cannot estimate the altitude with accuracy. − However, by updating the baseline value every day with the "day's pressure" at sea level (see on Internet broadcast website) then the altitude calculation would be fairly precise.
ENG-CANSAT-PICO-BMP280 (voir la source)
Version du 26 février 2022 à 23:19
, 26 février 2022 à 23:19→Pressure, SLP and altitude
Here the steps to follow with the BMP280 to estimate the altitude of the house:
Here the steps to follow with the BMP280 to estimate the altitude of the house:
# Find the hPa (or mmbar) pressure at Sea Level on a WebSite
# Find the hPa pressure at Sea Level on a WebSite
# Use the BMP280 sensor to read the pressure.
# Use the sensor and the BMP280 library to read the altitude.
# Calculate the height with the following code
# Calculate the correction value (for the air's colonne) in hPa = height-in-meter / 8.3
<syntaxhighlight lang="python">
from machine import I2C
# BME280 aslo work for BMP280
from bme280 import BME280, BMP280_I2CADDR
from time import sleep
i2c = I2C(1)
baseline = 1032.0 # day's pressure at sea level
bmp = BME280( i2c=i2c, address=BMP280_I2CADDR )
while True:
# returns a tuple with (temperature, pressure_hPa, humidity)
p = bmp.raw_values[1]
altitude = (baseline - p)*8.3
print( "Altitude: %f m" % altitude )
sleep(1)
</syntaxhighlight>
<nowiki># mean pressure at the sea level (not critical for SLP pressure)
<nowiki># mean pressure at the sea level (not critical for SLP pressure)
p = bmp280.pressure + compensation</nowiki>
p = bmp280.pressure + compensation</nowiki>
Just remind:
Just remind: