It's easy to use the BMP388 sensor with CircuitPython and the Adafruit CircuitPython BMP3XX module. This module allows you to easily write Python code that reads the barometric pressure, temperature and more from the sensor.
You can use this sensor with any CircuitPython microcontroller board or with a computer that has GPIO and Python thanks to Adafruit_Blinka, our CircuitPython-for-Python compatibility library.
CircuitPython Microcontroller Wiring
First wire up a BMP3xx to your board as shown below. You can use either I2C or SPI wiring, although it's recommended to use I2C for simplicity. Here's an example of wiring a Feather to the sensor with I2C:
-
Board 3V to sensor VIN (red wire on STEMMA QT version)
-
Board GND to sensor GND (black wire on STEMMA QT version)
-
Board SCL to sensor SCK/SCL (yellow wire on STEMMA QT version)
-
Board SDA to sensor SDI/SDA (blue wire on STEMMA QT version)
And an example of a Feather wired with hardware SPI:
- Board 3V to sensor VIN
- Board GND to sensor GND
- Board SCK to sensor SCK/SCL
- Board MOSI to sensor SDI/SDA
- Board MISO to sensor SDO
- Board D5 to sensor CS (or use any other free digital I/O pin)
Python Computer Wiring
Since there's dozens of Linux computers/boards you can use, we will show wiring for Raspberry Pi. For other platforms, please visit the guide for CircuitPython on Linux to see whether your platform is supported.
Here's the Raspberry Pi wired with I2C:
And an example on the Raspberry Pi 3 Model B wired with SPI:
- Pi 3V3 to sensor VIN
- Pi GND to sensor GND
- Pi MOSI to sensor SDI/SDA
- Pi MISO to sensor SDO
- Pi SCLK to sensor SCK/SCL
- Pi #5 to sensor CS (or use any other free GPIO pin)
CircuitPython Installation of BMP3XX Library
You'll need to install the Adafruit CircuitPython BMP3XX library on your CircuitPython board.
First make sure you are running the latest version of Adafruit CircuitPython for your board.
Next you'll need to install the necessary libraries to use the hardware--carefully follow the steps to find and install these libraries from Adafruit's CircuitPython library bundle. Our CircuitPython starter guide has a great page on how to install the library bundle.
For non-express boards like the Trinket M0 or Gemma M0, you'll need to manually install the necessary libraries from the bundle:
- adafruit_bmp3xx.mpy
- adafruit_bus_device
Before continuing, make sure your board's lib folder or root filesystem has the adafruit_bmp3xx.mpy, and adafruit_bus_device files and folders copied over.
Next connect to the board's serial REPL so you are at the CircuitPython >>> prompt.
Python Installation of BMP3XX Library
You'll need to install the Adafruit_Blinka library that provides the CircuitPython support in Python. This may also require enabling I2C on your platform and verifying you are running Python 3. Since each platform is a little different, and Linux changes often, please visit the CircuitPython on Linux guide to get your computer ready!
Once that's done, from your command line run the following command:
sudo pip3 install adafruit-circuitpython-bmp3xx
If your default Python is version 3 you may need to run 'pip' instead. Just make sure you aren't trying to use CircuitPython on Python 2.x, it isn't supported!
CircuitPython & Python Usage
To demonstrate the usage of the sensor, we'll initialize it and read the pressure, temperature and more from the Python REPL.
If you're using an I2C connection, run the following code to import the necessary modules and initialize the I2C connection with the sensor:
import time import board import adafruit_bmp3xx i2c = board.I2C() bmp = adafruit_bmp3xx.BMP3XX_I2C(i2c)
Or if you're using a SPI connection run this code instead to setup the SPI connection and sensor:
import time import board import adafruit_bmp3xx import digitalio spi = board.SPI() cs = digitalio.DigitalInOut(board.D5) bmp = adafruit_bmp3xx.BMP3XX_SPI(spi, cs)
Now you're ready to read values from the sensor using any of these properties:
-
temperature- The sensor temperature in degrees Celsius. -
pressure- The pressure in hPa. -
altitude- The altitude in meters.
For example to print temperature and pressure:
print("Pressure: {:6.1f}".format(bmp.pressure))
print("Temperature: {:5.2f}".format(bmp.temperature))
For altitude, you'll want to set the pressure at sea level for your location to get the most accurate measurement (remember these sensors can only infer altitude based on pressure and need a set calibration point). Look at your local weather report for a pressure at sea level reading and set the sea_level_pressure property:
bmp.sea_level_pressure = 1013.25
Then read the altitude property for a more accurate altitude reading (but remember this altitude will fluctuate based on atmospheric pressure changes!):
print('Altitude: {} meters'.format(bmp.altitude))
That's all there is to using the BMP388 sensor with CircuitPython!
# SPDX-FileCopyrightText: 2021 ladyada for Adafruit Industries
# SPDX-License-Identifier: MIT
import time
import board
import adafruit_bmp3xx
# I2C setup
i2c = board.I2C() # uses board.SCL and board.SDA
# i2c = board.STEMMA_I2C() # For using the built-in STEMMA QT connector on a microcontroller
bmp = adafruit_bmp3xx.BMP3XX_I2C(i2c)
# SPI setup
# from digitalio import DigitalInOut, Direction
# spi = board.SPI()
# cs = DigitalInOut(board.D5)
# bmp = adafruit_bmp3xx.BMP3XX_SPI(spi, cs)
bmp.pressure_oversampling = 8
bmp.temperature_oversampling = 2
while True:
print(
"Pressure: {:6.4f} Temperature: {:5.2f}".format(bmp.pressure, bmp.temperature)
)
time.sleep(1)
