Finally got everything working! The final problem was 100% my inability to read. As Orgia suggested, and catskull alluded to, my "link cable" was the final issue. I for some reason was using pin 19 instead of 16, so fixing this mistake got it talking immediately.

This doesn't account for my initial problem (and rich's), so I'll have to continue investigating if I want to use trash's most recent builds, but I'm happy to have it making noise in the meantime. If I find out anything more that may be useful to anyone else with similar issues, I'll follow up here.

Thanks again to everybody who offered help and advice - I'll post the finished build in another post when I'm done!


Thanks for keeping this thread going.
I haven't got it completely working but got to where perspectiveshifting where the arduinoboy receives the midi messages, the LEDs light up, but the gameboy doesn't play any sounds.

- I started again on the breadboard, is there anything obvious that stands out?
- I used CatSkull's unmodified code: currently at 9a3ed0c.
- I'm also powering the teensy with 5v from the gameboy itself so I've cut the USB power from the VCC, i thought this might have been an issue but the teensy is receiving midi. I also can see the device on my mac in the MIDI Studio app and can see messages coming from Live to Midi Monitor.
- I'm building with Teensyduino 1.52 on macOS 10.15.7
- I set the USB Type to "MIDI", "All of the Above" didn't want to connect to my computer as a midi device.
- It's a Teensy 3.2
- I set the Speed to 72MHz, the one just under the overlock setting.
- I wasn't sure that the serial to/from were around the right way to i tried both with no luck.

Currently the pins are:

Teeny 16 - link pin 3-SCK (green)
Teeny 17 - link pin 2-SIN (orange)
Teeny 18 - link pin 4-SOUT (red)
Ground   - link pin 6-GND (red)
n/a      - link pin 1-VCC
n/a      - link pin 5-SD

I might try seeing what the output of the link cable shows in the oscilloscope next but if anybody has any other ideas please let me know!

Last edited by richy486 (Oct 20, 2020 9:03 pm)


I'm seeing activity on the oscilloscope on the "Teeny 17 - link pin 2-SIN (orange)" when i play any notes.
I also noticed that the little arrow above each channel in mGB is showing up when I play notes, so messages are getting through to the gameboy but no sounds, is there something wrong with how mGB is setup?

Tried playing C-2 to C8 but still no sound.


It was the settings in mGB! I didn't really know what they should be set to but i moved the first wave option to the right a bit and it worked!!

Thanks for your help everybody