Fomu: An FPGA in your USB Port

What is an FPGA?

An FPGA is like a hardware emulator. It can change itself so that it can take on the characteristics of any other digital logic.

FPGAs are measured in resources called LUTs or LCs.

What is Fomu?

Fomu is an FPGA that fits in your USB port. It has foru buttons, 2 MB of SPI flash, an RGB LED, and an ICE40UP5K with 5280 LCs. It also has 128 kB of dedicated RAM, not counting the block RAM. Unlike many other PCBs, Fomu does not have a separate USB controller chip. This means that any projects that want to use the USB port must include a USB softcore.

What is this PCB?

This is Fomu EVT1. This is the original stretch prototype of Fomu. The schematics are the same, but much has changed: * Name changed from Tomu-FPGA to Fomu * Package changed from SG48 to WLCSP32 Additionally, some patches were needed to get this PCB working: * SO-8 for SPI flash was too small * Crystal footprint was upside-down These are yours to take home with you! Differences between EVT1 and EVT3: * Silkscreen on Raspberry Pi header * Populate Raspberry Pi header * Add PMOD pins to touchpads * Swap PMODa pins for I3C

Levels of Fomu

Fomu aims to be accessable on three levels:

1. Python / Interpreted
2. RISC-V
3. Verilog / FPGA