The firmware on a Tiny Tapeout FPGA demo board

You want to know what runs on the RP2350 of a Tiny Tapeout FPGA demo board, and why it is left as it is.

The programming the controller does is on Programming a Tiny Tapeout FPGA demo board. The faults it can show are on Tiny Tapeout FPGA demo board faults.

The boards run the Tiny Tapeout MicroPython SDK, release 3.1.0. With that release the SDK’s tt object comes up as Shuttle FPGA, and the Tiny Tapeout Commander connects. The ttdbv3 build the boards shipped with stalled at boot.

The stall is in the stock main.py of the RP2350, which calls DemoBoard(). That call probes I2C and can hang permanently, which makes the board unrecoverable without a physical reset. SDK 3.1.0 boots cleanly, and the board reports board present.

The public site depends on that boot. The site and the fpgas-tt daemon’s design list need the SDK to boot into DemoBoard(). A main.py that does nothing therefore takes the board off the Tiny Tapeout site, so the board’s main.py stays the SDK’s own.

The check that runs on the host is on fpgas-verify: the Tiny Tapeout demo boards.