A keychain that is also a working fm radio:D
- XIAO RP2040 microcontroller - edit firmware without any extra equipment
- RDA5807M - cheap and widely available FM radio chip
- Wired earphones act as an antenna for the radio
- Runs on a CR3032 coin cell battery
- 58 x 42.4mm (can be made even smaller if you don't want mounting holes)
- bom can be found as bom.csv
- Provide a battery and wired earphones.
- To flash the firmware, follow these instructions.
- Press the left knob down to turn on/off.
- Turn the left knob to adjust volume.
- Turn the right knob to adjust frequency.
- Adjust the earphone wire position and length to adjust reception of signals.
I made it because I like tiny things (my most prized pencilcase posession is a tiny calculator), I like keychains, and I like radios. I'm also new to hardware stuff so it was nice to get started with a simpler receiver. That, and I had impulse-bought RDA5807 chips a year or so ago. I also wanted a neat trinket I could give to radio people when I meet them at conventions and stuff. Additionally, my current radio is rather large... so I can't really carry it around anywhere.e.
The development process is logged in detail here and later here. It took me quite a while (~1 1/2 month of consistent work) because I was pretty much new to PCB design. I learned a lot about KiCad and the design process through this project.
I want to try making multiple at a time (larger scale) so that I have enough to go around. Also, harder projects (tiny calculator...).
