2022-05-14

Continuing my experiments with the IceSugar-Pro board, building cores using Yosys and friends, I now have EightThirtyTwoDemos running, using PMODs to provide VGA out, I2S audio out, PS/2 keyboard and mouse, and SD card. (The latter isn’t strictly necessary since the FPGA board already has an SD card slot – but it’s on the underside of the board and impossible to access while the IceSugar-Pro is inserted into the carrier board.)

So how did I go about wiring up the PMODs?

2022-04-19 – Part 1: Establishing communication

If I’m going to find the problem with EightThirtyTwo that’s preventing interrupts from working, I’m going to need some way of observing what’s going on. The CPU works in GHDL Simulation, works on Altera/Intel chips, and works on Xilinx chips so there must be something I’m doing which the Open Source toolchain doesn’t like. (Or I may have stumbled upon an actual bug…)

There are basically three problems to solve here:

• Capturing the state of internal signals
• Transporting those signals to the host computer
• Displaying them in a meaningful and readable format.

2022-04-18

I’ve been tinkering with the IceSugarPro board recently, which is a nice little SO-DIMM form factor FPGA board containing a Lattice ECP5 FPGA. It’s the successor to the earlier IceSugar board which contained a Lattice iCE40UP5k: despite not having an iCE40 series chip, the IceSugarPro retains the name!