This is the layout I came up with to preserve a standard QWERTY 104 key ANSI layout as much as possible, in as few layers as possible for a 30 key board.
1. The standard Gherkin uses a ProMicro (or clone) microcontroller, which has the Caterina bootloader by default.
2. If you have never flashed your ProMicro with QMK before, you will need to short the RST pin to GND to put it into bootloader mode (you only have 7 seconds to flash once it enters bootloader mode). You may need to touch the RST pin to GND **TWICE** in quick succession if it doesn't flash with just one touch.
3. Once connected to your computer, you should be able to flash using
4. Once you've been able to successfully flash the ProMicro, you should be able to use the `QK_BOOT` key for future flashes instead of shorting the RST pin.
The built-in `:avrdude` QMK target in Linux doesn't work with the default Caterina bootloader on the ProMicro, so we have to use avrdude separately. The instructions below are adapted from https://deskthority.net/workshop-f7/how-to-use-a-pro-micro-as-a-cheap-controller-converter-like-soarer-s-t8448.html
3. Next, plug in your device and re-run `ls /dev/tty*`
There should be one more device than was seen previously. Make a note of it. For me, it's `/dev/ttyACM0`.
4. Navigate to the directory with your `.hex` file in it. Touch the RST pin to GND **TWICE** in quick succession, then run the following within 7 seconds:
If you miss the 7 second window, the ProMicro will leave bootloader mode and the flash will fail. Hit `Control` + `C` to exit the `avrdude` command, connect RST to GND twice quickly, and try the `avrdude` command again.
# ProMicro Bootloader Replacement (Caterina to QMK DFU)
If you have an Arduino (or clone), you can replace the bootloader for a few extra features (e.g. no more 7 second "flash window", simplified Linux flashing, blinking LED when the ProMicro is in bootloader mode, ability to exit bootloader mode without unplugging your keyboard, among others).
The instructions below have been adapted from https://www.reddit.com/r/olkb/comments/8sxgzb/replace_pro_micro_bootloader_with_qmk_dfu/)
## Arduino Setup
1. Upload the ArduinoISP sketch onto your Arduino board (https://www.arduino.cc/en/Tutorial/ArduinoISP).
3. In `config.h` add the following. This is already set up in `qmk_firmware/layouts/community/ortho_3x10/wanleg`. You only need to do this on other keymaps.
The `QMK_ESC_` lines define where the bootloader escape key is. Refer to the `MATRIX_ROW_PINS` and `MATRIX_COL_PINS` lines in your keyboard's `config.h` to choose your preferred key.
You hit the bootloader escape key to exit bootloader mode after you've hit the QK_BOOT key to enter bootloader mode (e.g. if you change your mind and don't want to flash just then).
On a Gherkin, B4/F7 corresponds to the top-left corner key.
`B0` is an indicator light on one of the ProMicro's onboard LEDs. With QMK DFU, it will flash to indicate the ProMicro is in bootloader mode.
You can add `#define QMK_SPEAKER C6` if you have a speaker hooked up to pin C6. The Gherkin PCB already uses pin C6 in its switch layout, so you cannot use a speaker on a standard Gherkin.
4. Also, you should add `BOOTLOADER = qmk-dfu` to your `rules.mk` file, so it is flagged properly. Again, this is already set up in `qmk_firmware/layouts/community/ortho_3x10/wanleg`.
5. Once you've made the required edits, it's time to compile the firmware. If you use the `:production` target when compiling, it will produce the usual `.hex` file as well as `_bootloader.hex` and `_production.hex` files. The `_production.hex` will be what we want. This contains the bootloader and the firmware, so we only have to flash once (rather than flash the bootloader, and THEN flash the firmware).
Change `comPORT` to whatever port is used by the Arduino (e.g. `com11` in Windows or `/dev/ttyACM0` in Linux). Use Device Manager in Windows to find the port being used. Use `ls /dev/tty*` in Linux. Change `YOUR_production.hex` to whatever you've created in the previous step.
