Default Keymap for BM43
The default key mapping for the KP Republic BM43 RGB keyboard does not feature any modifiers for typing numerical and special characters.
We have provided a custom firmware for the keyboard that features numerical characters.
Download the custom firmware below and follow the instructions for flashing new firmware onto the keyboard.
Update Key Map
Download the custom firmware below and follow the instructions for flashing new firmware onto the keyboard.
Once downloaded, unzip the firmware file to retrieve the kprepublic_bm43hsrgb_fruitjam.hex file.
Download QMK Toolbox
Use the link below to download the QMK Toolbox for your computer's operating system.
This will allow you to flash the custom firmware to the KPRepublic BM43 keyboard PCB.
Flash Custom Firmware
Open the QMK Toolbox app and click the open button in the app window.
Locate and select the custom .hex file you downloaded.
Select ATmega32U4 in the dropdown next to the open button.
Connect the BM43 keyboard to your computer and go into DFU boot mode using the DFU key command, Fn(function) + Escape keys (or the DFU button the back of the PCB).
The following message will be displayed in the QMK Tool window:
DFU Device connected: ATm32u4DFU...
Click the Flash button. Wait for the firmware to write and finish.
Custom Keymap for bm43hsrgb
Now you can use the Fn(function) key to type numercials and special characters. Use the image above to reference the new keymap layout.
Build and Make a Custom Keymap
If you'd like to create your own custom keymap, you'll need to install the QMK command line tools and clone the QMK firmware GitHub repository to create your own keymap. You will need to build the firmware for the keyboard using the command line tools to create a new .hex file. Use the links below to learn how to build your own firmware and keymap.
Page last edited February 20, 2026
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