Here’s a new toy! It’s a BME280 temperature, humidity, and pressure sensor. Previously, I’ve used DHT22 temperature and humidity sensors and want to see if these are more accurate (not to mention that the DHT family of sensors that I’ve seen don’t do pressure) than the DHT22. The Bosch datasheet shows that these BME280 and BMP280 sensors are very accurate. They are also very easy on power.
These modules come in 3.3V and 5V varieties, choose wisely and remember not to try to feed 5 volts to the 3.3 volt version!
This board comes from Amazon and there seem to be many stores selling this sensor board. The actual sensor is small enough to fit inside a cellular phone and is targeted for small devices. the actual sensor is that small thing just to the right of the mounting hole!
Here are two more pictures. Sorry if they are a bit fuzzy, I used my phone instead of a real camera.
Yes, the sensor is very tiny!
All the support electronics reside on this side.
One possible snag is that I haven’t found any libraries for this board yet. Some say that a particular Adafruit library works if you specify the device address. I’ll have to find it again, however. The spec sheet gives the address range for the different outputs. There should be no conflict with the usual displays used with Raspberry Pi and Arduino projects. Hopefully it will work as expected. I read where someone tried to jump the address and let the smoke out. Bosch gives some code for reading pressure, but I’m not sure how I can apply that to Arduino. It may be easy once I delve into this in more detail. I think the code gives the pressure in Kilopascals. There is a formula for converting to different conventions. My goal is to have it read in inches of mercury.
Since the DHT libraries allow you to easily return the heat index, that would be doable as well as it involves simple calculations. So far, out of several DHT projects, I have only measured temperature and humidity.
I may look to using a small Raspberry Pi, most likely a Zero W since it includes WiFi. That will simplify things over doing WiFi on an Arduino Nano as far as keeping the project compact. The Zero also has lower power requirements than an Arduino Nano, I believe.
This will be a work in progress and this post may be updated as thoughts occur to reduce the number of posts to have to peruse.
