First PCB I have designed to use the
Adafruit ItsyBitsy. This is the
ATmega32u4 5V 16MHz version of the ItsyBitsy. They also have a 8MHz version as well as ARM M0 and M4 based ItsyBitsy, the firmware I have is written for the 16MHz ATmega32u4 version.
The matrix is the same as the
previous 4x4 PCBs, but this time it is staggered. It is as close an approximation to a
GNAP as I could make that would be modular, using all 1u keys.
The
firmware is the same as for the 4x4, only the pin mappings have been changed. Gerber files on
git.
The individual PCB's are under 100mm square and are cheap to have produced.
The assembled board using 3 PCB's. The center two switches can be replaced with a single switch and a 2U Cherry PCB mount stabilizer.
The bare board. You can see the solder bridges that hold the boards together. Also the 2U stabilizer for the space bar.
The ItsyBitsy is mounted on the left most board. The Mini USB connector can be placed on any of the boards, with the pigtail connecting it to the ItsyBitsy.
Close up of the ItsyBitsy. I am only using the pins along the edges of the board. The ItsyBitsy has the same bootloader as a ProMicro and you flash it the same way with AVRDUDE. It does have a tiny reset button which makes things a little easier.
The pinout.
I used another set of 3 PCBs solder together as the base of the keyboard.
M2 spacers and screws hold the top and bottom together.
It is possible to connect 4 boards together. I have tested the circuitry, but did not build it.
