Pi FM RDS Transmitter
If you like playing with electronics and computers, you probably know the Raspberry Pi.
This tiny and affordable computer is used in tons of DIY projects.
I wanted to try to make a FM transpitter to transmit mp3's and audiostreams to my vintage radio receiver.
The electronics is not difficult at all: just hook a SI4713 FM transmitter breakout board to your Pi, add some software and go ! (Adafruit https://www.adafruit.com/product/1958 is all you need)
The SI4713 is conected to the Pi GPIO header as follwos:
| Pi | Breakout |
|---|---|
| 3V3 | VIN |
| GND | GND |
| SCL | SCL |
| SDA | SDA |
| GPIO5 | RST |
The audio also is taken from the Pi, I connected the 3.5mm audio connector to the SI4713 LIN and RIN.
The available Pi software on the Adafruit website is for CircuitPython, but I did not want to install that, so I wrote a multifunctional configuration program in C.
You can find this in my Github repository https://github.com/on7lds/SI47123config. This only needs the WiringPi libraries (and, ofcourse, that I²C is working).
IMPORTANT: Check your local regulator to know what the maximum output power is you are legally allowed to use.