GPIO, USB problems

I’ve continued working on the firmware, and have run into two problems:

  1. I can only turn on one of the four LEDs on the Tiva board. The other three obstinately remain off. I don’t really need any LEDs, but this makes me think that I don’t understand the Tiva GPIO as well as I should, and that could cause other problems.
  2. After all of the USB stack initialization, the USB interrupt is never invoked, so nothing ever happens. It won’t enumerate when the USB is plugged into a host computer.

I put the partially reverse-engineered firmware of the Helix Labs bubble memory card for the Apple II on github. That’s not part of this RetroChallenge project, but it’s somewhat relevant because the card uses the same Intel bubble memory chipset as this project.

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