Mk19-pcb

mk19-pcb

The antithesis of 'keep it simple, stupid' - all the features, all the time.

Do you need...

• To use the Cyboard flex-pcb system? and extend it??
• Two Ultrafalcons...per side?
• SPI devices
  • PMW3360/3389 (right side only)
  • Dual GC9A01 TFTs per side
  • Quad-shift register-powered 32 pins for rows/cols? (available as a dedicated breakout here)
• 5-way switch or RKJXT for arrow keys?
• Perhaps enough RGB to illumine your entire home? (and almost certainly require 5v supplementary power - a feature, not a bug!)
• Audio and ADC breakouts? Reset switch? Power and debug breakouts?
• And use an existing RP Pico to do it?

...probably not, which is why I had to design my own pcb. So here it is...

the community that built it

• burkfers (research assistant extraordinaire)
• bomtarnes, chefcooke, walrus, wimads, yingeling, genki, others for design/3d printing help
• Quentin @ BKB & Erik @ Cyboard
• casuanoob (Falcon and diy pcb inspiration)
• tzarc, freznel, KarlK90, Dr. Faustroll, GeorgeN, (and others!) work on shift registers, pcbs, etc
• BKB discord crew; QMK discord; fingerpunch discord (Sadek and Melon, thanks!)
• cardiactuna for the font suggestion

rev2 improvements

• added rkjxt to dpad connector
• added resistor networks for col shift register pulldown
• relocated cyboard connectors
• fixed a bunch of incorrect pinout orderings
• changed from solder pads to pin jumpers
• re-thought led bypass
• moved TFTs to FFC cables, made 3 of them
• added external 5v power source option
• re-thought the test pins

design goals

• Provide a re-usable platform for the arcboards
• Make it possible to use the Cyboard flex-pcb system to save on the madness of per-key pcb soldering
• Minimize GPIO usage by moving cols/rows over to shift registers
• Reduce the amount of fiddly soldering and wire stripping a normal hand-wire build requires of you
• USB-C interconnects
• General improvements on the mk17 as a whole

feature details

• Raspberry PI Pico (RP2040) footprint - just add pin headers and solder away - or, solder directly to pads
• keys provided through the Cyboard flex-pcb system or, JST-XH 2.54 headers
• macropad using Cyboard flex-pcb keys, custom breakout pcb: https://github.com/christrotter/macropad-pcb (0.5mm pitch 16-pin FFC cable)
  • in future I'd just make this a custom FPC cable
• dpad using custom breakout pcbs 5-way switch or RKJXT
• diodes are configured for ROW2COL (to match Cyboard)
• USB-C split connector w. tzarc-grade voltage protection
• included a solder pad jumper to bypass if needed
• split-handedness via pin (jumper)
• SPI breakouts
  • PMW33xx
  • 3x TFT LCD (e.g. GC9A01)
  • shift registers (595 for rows, 589 for cols)
• pin breakouts
• power, debug, ADC, audio, reset
• remaining GPIO pins
• test points
• led breakouts w. bypasses
• keys
• 2x falcon pcbs
• indicator strip
• screen-mounted external indicators via USB-C
• this passes 5v/GND, level-shifted 5v LED DI/DO signal via USB-C cable
• pin for whatever else you want to add to the chain

pcb features

• two-layer pcb w. dual ground planes tied w. vias
• components configured as per datasheets
• bypass capacitors!
• care taken to avoid power running alongside signal for too long

schematic overview

mcu

keys via shift registers

peripherals

usb connections

breakouts