The Cantor is a 42-key split mechanical keyboard with an aggressive stagger. I have built a few of these, both for my own use and to sell.
Parts list
This is what we need to build a Cantor:
- PCB – I order these from JLCPCB
- Two STM32F401CC blackpill microcontrollers and sockets – can be picked up really cheaply from Aliexpress
- 42 choc v1 switches
- 42 choc-compatible 1U keycaps
- 2 TRRS jacks (PJ-320A)
- TRRS cable
- USB-C cable
- 10-12 rubber feet
All the example code in this guide will be assuming that the Vial firmware will be used. It requires having a working installation of the vial-qmk github repository.
Flashing Controllers
Flash each controller to test they work, and to define which controller belongs to which side of the keyboard.
Firstly test that your firmware compiles:
qmk compile -kb cantor -km vial
Then flash each controller in turn:
qmk flash -kb cantor -km vial --bootloader dfu-util-split-left
qmk flash -kb cantor -km vial --bootloader dfu-util-split-right
If you get the message Waiting for USB serial port - reset your controller now (Ctrl+C to cancel) you will need to bridge BOOT0 to VCC (via BOOT0 button or jumper), short RESET to GND (via RESET button or jumper), and then let go of the BOOT0 bridge.
Once you have done this then label the controllers so you are absolutely sure which is which.
If QMK encounters errors it will let you know. Fix any errors before proceeding to the next step.
PCB
These steps will get us a PCB that we can test:
- Solder the sockets to the PCB
- Solder the TRRS jacks to the PCB
- Socket the controllers (for this build both controllers will be face down)
- Connect the two halves with the TRRS cable
Testing
Plug the keyboard into a computer, and short every single socket to test that the right key codes are sent. I use QMK Configurator to test this.
If anything is awry, fix it before soldering switches.
Soldering switches
Press each switch into the PCB, and ensure they are straight. Then solder each one in turn.
Once the switches are soldered, repeat the same tests as before. If any switches do not work, or behave oddly (repeated keys, excessive chatter etc.) then resolder them.
Final touches
Apply 5-6 rubber feet to the bottom of each half of the PCB, and then add keycaps.