2018-10-15 (M) ModuKey

The ModuKey project was taken off the back-burner. The boards were ready for data connections. Admittedly, this is a daunting task because once data lines are added, there is significant troubleshooting afterward. The IO expander ICs can be diagnosed for their connections, the I2C addresses must be assigned, inter-board connections have to be solid before subsequent boards can be seen by the controller. Trust me, it is not a cakewalk when things go poorly.

The next step in assembling the boards was to buy and add spacers so the boards could be laid out exactly as they would be once populated with switches. Before this, the boards were always upside down, so the ICs wouldn't be sandwiched between the circuit boards and the wooden platforms. The spacers were barely large enough to fit the #6 screws used to hold the boards down. Similar spacers should be available in 3mm or 4mm to accommodate either size screw.

Spacers installed

After the boards were arranged, jumpers were installed from each board to board to connect the Vcc, GND, SDA, and SCL pins to all the boards. Since it was a bus line, the boards could be connected in any arrangement: star, loop, daisy chain, or any combination. By the end, this keyboard will be a combination of daisy chains and stars.

Connecting data lines between boards

The data line started at the controller on the back of the circuit board shown below. It ran to the circuit board mounted at the top of the wooden block, then down the two in the middle which were linked with short jumpers, then down the small board at the bottom. The wire used was 26 AWG copper purchased from a surplus store.

One half wired for data

ModuKey on GitHub

The rest of the posts for this project have been arranged by date.

First time here?

Completed projects from year 1
Completed projects from year 2
Completed projects from year 3
Completed projects from year 4
Completed projects from year 5

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