Proton C Conversion

Since the Proton C is a drop-in replacement for a Pro Micro we've made it easy to use. This page documents a handy automated process for converting keyboards, as well as documenting the manual process if you'd like to make use of Proton C features that aren't available on Pro Micros.

Automatic Conversion

If a board currently supported in QMK uses a Pro Micro (or compatible board) and you want to use the Proton C, you can generate the firmware by appending CONVERT_TO_PROTON_C=yes (or CTPC=yes) to your make argument, like this:

make 40percentclub/mf68:default CTPC=yes

You can add the same argument to your keymap's rules.mk, which will accomplish the same thing.

This exposes the CONVERT_TO_PROTON_C flag that you can use in your code with #ifdefs, like this:

#ifdef CONVERT_TO_PROTON_C
// Proton C code
#else
// Pro Micro code
#endif

If you get errors about PORTB/DDRB, etc not being defined, so you'll need to convert the keyboard's code to use the GPIO Controls that will work for both ARM and AVR. This shouldn't affect the AVR builds at all.

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 like to your config.h:

#define CONVERT_TO_PROTON_C_RXLED

Feature Conversion

These are defaults based on what has been implemented for ARM boards.

Feature

Notes

Audio

Enabled

RGB Lighting

Disabled

Backlight

Forces task driven PWM 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

Partial - heavily dependent on enabled features

Manual Conversion

To use the Proton C natively, without having to specify CTPC=yes, you need to change the MCU line in rules.mk:

MCU = STM32F303

Remove these variables if they exist:

  • BOOTLOADER

  • EXTRA_FLAGS

Finally convert all pin assignments in config.h to the stm32 equivalents.

Pro Micro Left

Proton C Left

Proton C Right

Pro Micro Right

D3

A9

5v

RAW (5v)

D2

A10

GND

GND

GND

GND

FLASH

RESET

GND

GND

3.3v

VCC 1

D1

B7

A2

F4

D0

B6

A1

F5

D4

B5

A0

F6

C6

B4

B8

F7

D7

B3

B13

B1

E6

B2

B14

B3

B4

B1

B15

B2

B5

B0

B9

B6

B0 (RX LED)

C13 2

C13 2

D5 (TX LED)

You can also make use of several new pins on the extended portion of the Proton C:

Left

Right

A43

B10

A54

B11

A6

B12

A7

A145 (SWCLK)

A8

A135 (SWDIO)

A15

RESET6

Notes:

  1. On a Pro Micro VCC can be 3.3v or 5v.

  2. A Proton C only has one onboard LED, not two like a Pro Micro. The Pro Micro has an RX LED on D5 and a TX LED on B0.

  3. A4 is shared with the speaker.

  4. A5 is shared with the speaker.

  5. A13 and A14 are used for hardware debugging (SWD). You can also use them for GPIO, but should use them last.

  6. Short RESET to 3.3v (pull high) to reboot the MCU. This does not enter bootloader mode like a Pro Micro, it only resets the MCU.