This page documents the automated process for converting keyboards to use drop-in replacement controllers. This process is designed to be easy to use and can be completed in a few simple steps.
Each converter category is broken down by its declared `pin compatibility`. This ensures that only valid combinations are attempted. You can generate the firmware by appending `-e CONVERT_TO=<target>` to your compile/flash command. For example:
You can also add the same `CONVERT_TO=<target>` to your keymap's `rules.mk`, which will accomplish the same thing.
?> If you get errors about `PORTB/DDRB`, etc not being defined, you'll need to convert the keyboard's code to use the [GPIO Controls](gpio_control.md) that will work for both ARM and AVR. This shouldn't affect the AVR builds at all.
### Conditional Configuration
Once a converter is enabled, it exposes the `CONVERT_TO_<target_uppercase>` flag that you can use in your code with `#ifdef`s, For example:
To ensure compatibility, provide validation, and enable future workflows, a keyboard should declare its `pin compatibility`. For legacy reasons, this is currently assumed to be `promicro`. The following pin compatibility interfaces are currently defined:
If a board currently supported in QMK uses a [Pro Micro](https://www.sparkfun.com/products/12640) (or compatible board), the supported alternative controllers are:
The Proton C only has one on-board LED (C13), and by default, the TXLED (D5) is mapped to it. If you want the RXLED (B0) mapped to it instead, add this line to your `config.h`:
```c
#define CONVERT_TO_PROTON_C_RXLED
```
The following defaults are based on what has been implemented for STM32 boards.
| [Backlight](feature_backlight.md) | Forces [task driven PWM](feature_backlight.md#software-pwm-driver) until ARM can provide automatic configuration |
| USB Host (e.g. USB-USB converter) | Not supported (USB host code is AVR specific and is not currently supported on ARM) |
| [Split keyboards](feature_split_keyboard.md) | Partial - heavily dependent on enabled features |
### Adafruit KB2040 :id=kb2040
The following defaults are based on what has been implemented for [RP2040](platformdev_rp2040.md) boards.
| [RGB Lighting](feature_rgblight.md) | Enabled via `PIO` vendor driver |
| [Backlight](feature_backlight.md) | Forces [task driven PWM](feature_backlight.md#software-pwm-driver) until ARM can provide automatic configuration |
| USB Host (e.g. USB-USB converter) | Not supported (USB host code is AVR specific and is not currently supported on ARM) |
| [Split keyboards](feature_split_keyboard.md) | Partial via `PIO` vendor driver - heavily dependent on enabled features |
STeMCell has support to swap UART and I2C pins to enable single-wire uart communication in STM chips. The following additional flags has to be used while compiling, based on the pin used for split communication:
The Bonsai C4 only has one on-board LED (B2), and by default, both the Pro Micro TXLED (D5) and RXLED (B0) are mapped to it. If you want only one of them mapped, you can undefine one and redefine it to another pin by adding these line to your `config.h`:
Feature set is identical to [Adafruit KB2040](#kb2040). VBUS detection is enabled by default for superior split keyboard support. For more information, refer to the [Community Edition pinout](platformdev_rp2040.md#rp2040_ce) docs.
If a board currently supported in QMK uses an [Elite-C](https://keeb.io/products/elite-c-low-profile-version-usb-c-pro-micro-replacement-atmega32u4), the supported alternative controllers are:
