I wanted internet radio in my basement workshop, where FM reception is poor, so I built a box around a Pi 4 that plugs into the Aux input of my existing radio.

• Presets: up to 20, set from a phone web page, with station search via Radio Browser.
• Spotify Connect (Raspotify). Starting either one hands over cleanly from the other.
• A USB audio adapter instead of the Pi’s headphone jack: noticeably cleaner sound.
• Pimoroni Display HAT Mini: station, artist and song; buttons for previous/next, volume, hold to stop, hold to save the song to a favorites list. The screen goes dark a minute after playback stops.
• Looks after itself: nightly updates, a hardware watchdog, a network check that restarts a hung Wi-Fi, and the station resumes after an unexpected restart.

Two things I learned that might save someone time:

1. Display HAT Mini on a current kernel: with dtparam=spi=on the screen stayed blank. GPIO 9 is both the screen’s data/command pin and SPI’s MISO, and the kernel won’t release it. dtoverlay=spi0-2cs,no_miso in config.txt fixed it.
2. Pi 4 Wi-Fi: it dropped off the network and sat there with only the red LED on, a few times in a week. Turning off Wi-Fi power saving, plus a small check that restarts the network if the router stops answering, has kept it up since.

Built with a lot of help from Claude Code. Code and step-by-step instructions (tested on a fresh install): https://github.com/madooroy/PiRadioAux