Hardware

Electronics

Currently DigitalRooster is built from these Components:

The total cost is about 120U$ on digikey while the rotary encoder alone accounts for 25US$.

Caveats

The Raspberry Pi has few hardware PWM pins. One is used for SPI, the other one I would like to use for Backlight control. Unfortunately the Pin is right next to the I2S pin for the speaker bonnet and may cause interference when connected through the speaker bonnet. As a quick fix I just cut the pin and soldered a flying wire from the Pi to the backlight pad of the TFT - not the most professional way to deal with EMI issues but it remedies the noise on the speakers.

Upcoming hardware

I am working on (my first) design of an extension PCB with three audio channels, integrated RTC, I2C PWM driver for backlight and possible LED illumination. This will also remedy the caveats and should work on Raspberry Pi and Banana Pi.

rendering of red PCB

Casing

The housing is printed on a Prusa MK3. You can find the STL-files here. Make sure you scale the housing with about 0.5% so the side panels fit in. otherwise you will have problems mounting.