Introduction
This guide will help you read barometric pressure from your PiicoDev® Pressure Sensor and a Micro:bit
To follow along, it's best to have:
- A Micro:bit V2
- A PiicoDev Pressure Sensor MS5637
- A PiicoDev Adapter for Micro:bit
- A PiicoDev Cable
- (Optional) A PiicoDev platform helps secure everything together.
We'll program with Thonny in this tutorial. If you haven't used Thonny before, check out our guide for Programming a Micro:bit with Thonny. If you prefer, you can program your Micro:bit using python.microbit.org instead (see our guide).
Contents
Connect the PiicoDev sensor to your Micro:bit
Plug your Micro:bit into the PiicoDev adapter (buttons + LED matrix facing up), connect your motion sensor to the adapter via the PiicoDev cable and connect your Micro:bit to your computer with a USB lead.
If you're unfamiliar with connecting PiicoDev modules, read the PiicoDev Connection Guide before proceeding.
Download the PiicoDev Modules and Example Code
Download the following files and save them to your working directory (Right Click > "Save Link As")
- PiicoDev_Unified.py - The PiicoDev Unified Libraries: Drives I2C communications for PiicoDev modules
- PiicoDev_MS5637.py - The device driver.
- main.py - an example script for this PiicoDev Sensor
It will be best to keep this file wherever you like to keep your coding projects eg. Documents > PiicoDev
Example Code
We'll be working in Thonny - if you're unfamiliar working with Thonny see our guide for Thonny and Micro:bit.
Open Thonny, connect to your Micro:bit and upload the three files. (Hint: View the files menu with View > Files)
Restart your Micro:bit with keyboard shortcut, Ctrl+D and it should begin printing barometric pressure measurements in hectopascal, which is equivalent to millibar - a commonly used unit for describing barometric pressure: 1hPa = 100Pa = 1mbar.
Above: Pressure data streams up the Shell, while the Plot shows historic data.
Remix
Did you know you can also infer altitude from air pressure? Comment out the pressure print statement and uncomment the altitude print statement. Run the script again and now the Pico will infer altitude-above-sea-level from air pressure. There can be a bit of error here since your local weather conditions will affect the reading. You can optionally pass in the local air pressure at sea level to the read_altitude() function to correct for weather effects. You can find the current air pressure at sea level for your area with an internet search.
Conclusion
We can now measure air pressure from our PiicoDev Pressure Sensor, and use it to infer altitude.
If you make something cool with this starter project we'd love for you to share it on our forums! And if you'd like some help with this guide, start the conversation below - We're full-time makers and here to help!
