We live on a planet with an atmosphere, a big ocean of gaseous air that keeps everything alive – and that atmosphere is constantly bouncing off of us, exerting air pressure on everything around us. But, how much air is in the atmosphere, bearing down on us?
This absolute pressure sensor, ST LPS22HB (a.k.a LPS22) can quickly and easily measure this air pressure, useful when you want to know about the weather (are we in a low-pressure or high-pressure system?) or to determine altitude, as the air thins out the higher we get above sea level. For example, at sea level, the official pressure level is 1013.25 hPa. You can use this sensor to measure the current pressure where you are right now to compare.
The LPS22 is the World’s Smallest sensor (according to ST) and it is surprisingly tiny – only 2x2mm. So you’ll see this sensor show up in wearables and watches where space is at a premium. It has a wide measurement range of 260 to 1260 hPa with 24-bit pressure data measurements that can be read up to 75 times a second (Hz), you can be confident that you always have an up to date and precise measurement. It’s pretty dang accurate too, with the ability to measure absolute pressure within 0.1 hPa after one-point calibration (± 1 hPa before calibration).
These days, helpful little sensors like the LPS22 are often quite little and tend to come in surface-mount packages that make them tricky to use with breadboards. With that in mind, we’ve taken the LPS22 and put it on a breakout board with level shifting circuitry and a voltage regulator. This means that not only can you use it with a breadboard, but you can use it with a wide range of devices that have either a 3.3V logic level, like a Raspberry Pi or CircuitPython-compatible Metro M4 Express, or with a 5V logic level device like a Metro 328 or Arduino Uno.
Furthermore, we’ve included SparkFun Qwiic compatible STEMMA QT connectors for the I2C bus so you don’t even need to solder! All you need to do is plug in a compatible cable, wire it up to your device using one of our wiring diagrams and you’re ready to write some code to start reporting measurements.
To make the coding easier, we’ve written libraries for Arduino and CircuitPython or Python along with accompanying example code, so all you have to do is gather your supplies and follow our instructions and you can know just how much air is sloshing around in your vicinity.