Asicle rollover: Have you played Wordle on raw silicon yet? (This is a resubmission from MPW5.).

Clone this repo:


  1. 99b64f7 final gds oasis by Jeff DiCorpo · 1 year, 8 months ago main
  2. 01cae45 Change GPIO modes and rebuild by Tamas Hubai · 2 years, 4 months ago
  3. dfcf619 Rebuild with DECAP_PERCENT=100 by Tamas Hubai · 2 years, 4 months ago
  4. 98ea4e9 Fix broken symlink by Tamas Hubai · 2 years, 4 months ago
  5. 8ec3fb3 Add build outputs by Tamas Hubai · 2 years, 4 months ago


Screenshot of VGA output

Okay, so Wordle took the net by storm and was ported to a myriad of platforms including retro computers and microcontrollers with tight constraints. But have you played it on raw silicon yet?

After tapeout using the OpenLane flow and the Caravel harness, put the manufactured chip on a board with 6 push buttons, a VGA connector through resistor ladders as well as the usual Caravel requirements (voltage regulator, clock source, flash memory & passives) and start playing.

Sources live in verilog/rtl:

  • display.v is responsible for showing the game screen. It builds on vga.v for interfacing with VGA hardware, frame.v for the screen layout and square.v for rendering individual squares with letters.
  • control.v contains code for the game logic and its inputs. It uses wordlist.v to generate solutions and to check whether words are valid, eval.v to calculate the square colors and debounce.v to separate real button presses from fake ones.
  • top.v integrates the two aforementioned parts while user_project.v and user_project_wrapper.v provide connections to the Caravel harness
  • font.mem contains the Apache licensed font Roboto Bold rendered at 38 pts
  • wordlist.mem contains a public domain word list
  • picks.mem contains indices of a selection of 1000 words to be used as solutions, filtered by removing plurals, past participles, proper nouns and a few obscure words and then sorting by their frequency on the English Wikipedia