It uses the hardware on the raspberry pi that is actually meant to generate spread-spectrum clock signals on the GPIO pins to output FM Radio energy. This means that all you need to do to turn the Raspberry-Pi into a (ridiculously powerful) FM Transmitter is to plug in a wire as the antenna (as little as 20cm will do) into GPIO pin 4 and run the code posted below.
- SFTP the pifm.c and sound.wav files on to your Raspberry PI.
- You will need to enable SHH to SFTP a file on your Raspberry PI
- From the SHH terminal window, compile the pifm.c for your distro of linux. By default gcc will produce a a.out file as the compiled program.
gcc -lm -std=c99 pifm.c
- Run the output. You must run the application as an administrator (sudo) because this application uses direct memory management to access the GPIO pins.
sudo ./a.out sound.wav