With the compass functionality tested on a breadboard, the next step is to transfer it to a universal prototyping board, adding a status display and IO expansion ports to drive a LED ring that simulates the horizon. For the board, I am going to use the Takachi TNF 89-136.
In the left half of the universal prototyping board, I placed the remaining components: the DS3231 RTC clock, the MicroSD card reader, and a bigger 128x64 OLED display. For data exchange, was going to connect the two Nano over the serial line interface. But before that, I run into severe RAM space issues. The MicroSD card driver requires >512 Bytes buffer space, the bigger 128x64 OLED reserves a larger frame buffer, exhausting the 2K RAM space of the Nano without having written any code yet.