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This repository contains the kicad and gerber files for the ström keyboard. The PCB and plates are below 100mm x 100mm. The ström is a split keyboard with 20 column staggered keys on each half.
The PCB supports through hole diodes as well as 0805 diodes.
The ström is assembled in a similar fashion as most sandwich style keyboards such as the Let's Split or the Gherkin. Unlike the Let's split however, the PCB is not invertible, instead it offers two potential footprints for the TRRS jack with the Pro Micro in between, the ström also doesn't require any jumper settings. The Pro Micro is mounted with the USB towards the PCB on both sides to save space.
By default the ström uses the QMK serial connection to communicate between the two halves, although either I2C support or shared RGB backlighting can be added.
I2C has not been tested but should generally be working, follow the instructions below.
In order to use I2C, Pin 2 (SDA) on the Pro Micro has to be connected to the dormant trace in the TRRS connection, a pad to do so is provided as "DT2" right next to Pin 2, simply jump from the pin to the pad with a short wire.
Additionally I2C requires a 4.7kΩ pull-up resistor to each data line, the best place to add them is one of the empty TRRS jack footprints. VCC is connected to the right topmost pad, below is DT2 and the other data trace DT1 is the bottommost pad on that side, the single pad on the left side is GND. Simply use a SMD resistor between VCC and DT2 and solder the legs of a through hole resistor between VCC and DT2.
Use a 3 trace RGB strip, tap DT2, VCC and GND to propagate the color to the other half. Use either pin 9 or pin 10 on the pro micro as RGB pin.
The ström supports QMK. You can use a flat screw driver to short RST and GND instead of soldering a switch on SW1.
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