Breakout Garden Specs

I’ve been enjoying using breakout garden modules, so I’m looking at putting together a mechanical keyboard with some breakout garden parts, this would involve:

  1. Using the trackball directly (soldered to PCB). For this, it would be really helpful to have a kicad footprint for the device, or failing that a mechanical drawing. I’m anticipating that if I provide the correct 0.1" holes and mounting holes matching the trackball board I should be able to connect one up with a header strip and some standoffs.

  2. Providing some breakout garden sockets on the keyboard for connecting breakout boards, e.g. to add a display. For this, it would be great to know the pinout and any other notes for compatibility, including the footprint and/or part number of the edge connector. I’m assuming each pair of pins in the two rows is connected together on the breakout garden boards themselves (since on the breakout boards there is a via that ends up between the connector contacts), and the signals go pretty much straight to compatible pins on the Pi. If I can get hold of the connectors that’s great, otherwise I was thinking I would get the extenders and try to desolder the connectors from the little PCBs.

I was also wondering about the INT pins - are all of them connected to the same IO on the Pi, e.g. as open collector? Which boards actually use them (e.g. does the trackball require this?).

I’m thinking of providing a few I2C and one or two SPI connectors on the keyboard, so it would be useful to know the details of both. I’ll be using something like an STM32F405 MCU, so I’ll need to port the drivers as well, but it’s mainly the pinouts/footprints I’m interested in at the moment.

Thanks in advance for your help!