phiboard

in progress...

Goals

• fully reversible pcb including hotswap sockets, MCU, OLED screen
• wireless using the XIAO BLE as MCU
• low profile (choc kailh) and thin PCB + components
• no visible screws from the top
• no visible seams from the top
• custom graphics and silk screen
• super easy, local zmk development

Manual additions after Ergogen

Ergogen is used to generate most parts of the PCB. From within the ergogen folder, this can be done using:

ergogen . && cp output/pcbs/pcb.kicad_pcb ../kicad-prj/

However, various smaller modifications as well as the reversible OLED and silkscreen graphics are placed manually by hand. It is likely that this could be done through ergogen as well, feel free to fork and adjust my config. All modifications are listed in here:

• Removed silksceens from diodes and modified silksceen for the battery pads. Be careful with this, as it make messing up the diode configuration very easy!
• Wired up MCU and keys in a reversible fashion
• Included reversible OLED
• Put on silkscreens on front porsche-front-big.kicad_mod and back porsche-back-big.kicad_mod

Customize Graphics

In graphics you can find the source images used in this project. There are two types of graphics.

Silkscreen

The silksceen uses the porsche images. To use a different image you have to open kicad > image converter. In here you can load your desired image, choose an output size and threshold and save it as footprint on F.Silkscreen. In order for KiCad to detect your custom footprints, you have to save them to a folder with the extension .pretty like in kicad-prj/graphics.pretty/. Lastly you need to tell KiCad where to find your footprints. If you decide to use my project and its graphics.pretty folder then KiCad should automatically pick it up through the fp-lib-table. Else, you can specify your .pretty path in Preferences > Manage Footprint Libraries... > Project Specific Libraries.

Solder Images

In the palm of the hand there is a little empty space on the PCB which I decided to use with images which are printed on there using solder. I got the idea from this video. Here is the workflow to put your own images on there: You will most likely have a .png or .jpg image, which needs to be transformed to .svg. For this you can use popular online tools like convertio.co. Optionally you can try to optimize your svg using this website, although it didn't make much of a difference for me. Next, we need to transform our svg into an array of points, for which i used this website. Lastly, you can replace the point array in ergogen/footprints/phi-caps for the front side or ergogen/footprints/phi-logo for the back side.

Parts

40 keys, 20 per side

• 40 choc kailh switches
• 40 choc kailh keycaps
• 40 choc hotswap sockets
• 40 smd diodes 1N4148
• 2 xiao ble
• 2 oled 0.91 inch i2c (optional)
• 2 batteries 3.7v (optional, requres cable otherwise)

Firmware

Usually ZMK is compiled throug a GitHub actions workflow. However, I prefer to use it locally using a docker devcontainer. The devcontainer is provided by the official ZMK project.

Setting up the ZMK docker toolchain

nix develop     # or install devcontainer cli otherwise
cd <path-to-phiboard>/firmware
./setup-zmk.sh  # this may take a while

Compiling the ZMK firmware

nix develop     # or install devcontainer cli otherwise
cd <path-to-phiboard>/firmware
./build.sh  # clean build, is needed the first time
./build.sh --cached   # faster, if a build has been done before
# the firmware is now located at <path-to-phiboard>/firmware/(left|right).uf2

Flashing the firmware

• connect mcu with pc
• double press the reset button
• the file explorer should now show a usb media
• copy the corresponding .uf2 firmware to the usb media
• it should now auto-eject and run the new firmware

Fighting with ZMK

• spend a lot of time on local toolchain and scripts
• other projects may have their config files in different places
• explain most important files which the user might want to change (and where)
• confusing, overwhelming (at first)
• flash reset firmware to fix problems
• dtsi is "weird" because of the way the matrix is connected (only on prototype)
• right overlay columns are reversed because its mirrored but pcb is non-mirrored
• main half controls layers of secondary half -> perhaps need to flash both sides for keymap to take new changes
• displays have close to 0 documentation at all

Thanks

• to https://github.com/MvEerd/ergogen/tree/mveerd for ergogen
• to https://flatfootfox.com/ergogen-introduction/ for teaching ergogen
• to https://github.com/Pipshag/goosekb for inspiration on ergogen and zmk
• to https://www.youtube.com/watch?v=ohu4tZ4qov8 for finally making me follow through
• and many, many more!