Hi All!
It would be awesome to build a smartwatch with bluetooth capability and I was looking for advice on how.
I found a part that has the RP2040 MCU, an LCD screen, and other components I would want, but it doesn’t have bluetooth. I know nothing about hardware - this would be my first project - and I don’t understand which bluetooth modules would be compatible with it (picture of pin diagram below) or how to wire it.
Would you be able to guide me on compatible bluetooth modules and wiring?
Thank you!!!
Hi Bob,
Welcome to the forum 
It’s a real shame that Bluetooth isn’t built in to that module but I suppose there is only so much space available on the back-side of an LCD and antennae take up a lot of room on a PCB.
Wiring may be a little trickier than normal because the headers on the Round LCD are 0.05" pitch instead of the standard 0.1" so keep an eye out for that.
Since the MCU built in is just the RP2040, that module is basically a Raspberry Pi Pico. Any accessories or code that works with the Pi Pico should also work, you’ll just need to double-check what’s already in use by the built-in accelerometer/LCD etc to make sure there aren’t any conflicts.
My first thought would be to try something like the Adafruit Bluefruit LE SPI Friend which will allow you to add Bluetooth Low Energy (BLE) via the SPI interface of the RP2040. Read the tutorial with the link below.
The HC-05 and HC-06 classic Bluetooth modules are also an potential option if you don’t mind a more challenging configuration.
