Keyboard Builders' Digest / Tips & Tricks
New flexible PCB
Alakuu from Skree.us revised his flexible PCBs and designed a new XIAO-Flex MCU breakout board.
Published September 4, 2023
Marshall Somerville (aka Alakuu/Skree/TheBigSkree) from Skree.us finished his big revision for flexible PCBs in conjunction with a new XIAO-Flex MCU on breakout board that allows for far less time spent on soldering small wires:
The whole build took 21 total solder joints (51 if you count each wire in a parallel set as a joint). Compared to single key amoebas it's an unreal reduction in the time and effort required to build any flat or curve welled keyboard! – Alakuu.
It uses FFC cables to connect to the flexible PCBs for rows, and columns connect with only a single solder joint per column that then plugs directly into the breakout board. This allows for also complete removal of a breakout board + MCU for easier diagnostics and replacement if something goes wrong.
The breakout board has actual low voltage cutoff extra circuitry and can either use the included LIR2450 pin cell battery or simply solder on whatever lithium battery connection you'd want!
I also added LED control with a 3.3v driving circuit that can be change with the flick of a switch to a level shifted 5v USB power delivery to the LEDS along with proper led logic voltage. My version 1 of flexible pcbs has sold with rave reviews for about 9 months now, this revision I hope will help people build any flat or curve welled keyboard – Marshall.
These PCBs support Choc v1 or MX switches, but according to Marshall with his design workflow doing custom distances and different switch types is super easy.
Finally, the Mk08 (module name) version hit a road bump with the circuit design but when it's revised there will be an up to 12x12 + SPI, I2C (3 and 4) along with multiple free extra GPIO pins all addressable with both FPC and JST-SH connections for builds with or without flexible PCBs.
So MX or Choc, LED or not, even screw mounted or simply hotglued, this is a versatile system for all kinds of builds.
Resources
- https://skree.us/ (5% discount with the KBDNEWS coupon code)
- XIAO Flex (board only)
- XIAO Flex (kit)
- Skree Claw MX flexible PCB Xiao-flex on github
Published on Mon 4th Sep 2023. Featured in KBD #134.