A Blinky Project for the ULX3S Board

Here is a blinky project for the ULX3S board with a 45F FPGA.

I downloaded the latest version of Yosys from https://github.com/YosysHQ/oss-cad-suite-build/releases/latest.

The blinky.v file can be simulated under Verilator, just type make at the command line. It will use blinky_tb.cpp as the testbench and that requires testb.h.

To build the ULX3S bitstream, do a make ulx3s.bit . If you don't have a 45F FPGA chip, change the nextpnr-ecp5 --45k line in the Makefile to something more suitable. If you have an older board, you will need to find a constraints file that matches your board. Have a look in https://github.com/emard/ulx3s/tree/master/doc/constraints .

Making the ulx3s.bit file requires blinky.ys which tells Yosys what to do, and ulx3s_v20.lpf to tell nextpnr what to do.

Use ujprog from https://github.com/emard/ulx3s-bin to program your board.

Other Projects and Tips

If you are using the serial link to the FT231X chip, you need to disable hardware flow control. With minicom, ctrl-A O, Serial port setup, F, Exit.

As I get other projects to work on the board, I'll put links below:

• Echo characters on the USB serial port
• Tic Tac Toe using the serial port, and with HDMI output
• A 4-bit CPU using the serial port
• A HDMI test pattern generator based on Emard and Dan Gisselquist's code