Dactyl
See https://github.com/adereth/dactyl-keyboard
The Dactyl uses the Teensy Loader.
Linux users need to modify udev rules as described on the Teensy
Linux page.  Some distributions provide a binary, maybe called
teensy-loader-cli.
To flash the firmware:
- 
Build the firmware with make handwired/dactyl:<keymapname>, for examplemake handwired/dactyl:default
- 
This will result in a hex file called handwired_dactyl_<keymapname>.hex, e.g.handwired_dactyl_default.hex
- 
Start the teensy loader. 
- 
Load the .hex file into it. 
- 
Put the Teensy in firmware-loading mode: - If your current layout has a RESET key, press it.
- If you lack a RESET key, press the reset button on the Teensy board itself.
 
- 
Click the button in the Teensy app to download the firmware. 
To flash with ´teensy-loader-cli´:
- 
Build the firmware as above 
- 
Run <path/to/>teensy_loader_cli -mmcu=atmega32u4 -w handwired_dactyl_<keymapname>.hex
- 
If you like, you can do both at once: make handwired/dactyl:<keymapname>:teensy
- 
Put the Teensy in firmware-loading mode: - If your current layout has a RESET key, press it.
- If you lack a RESET key, press the reset button on the Teensy board itself.