Flashing Firmware

The last step is to flash compiled firmware to your microcontroller. RMK supports flashing the firmware via uf2 bootloader or debug probe.

Use uf2 bootloader

Flashing using uf2 bootloader is easy: set your board to bootloader mode, then a USB drive should appear in your computer. Copy the uf2 firmware to the USB drive, and that's it!

If you're using macOS, an error might appear, you can safely ignore it.

Tips for nRF52840

For nRF52840, you need to check whether your have a uf2 bootloader flashed to your board. If you can enter bootloader mode, there will be an USB drive shown in your computer. If there's INFO_UF2.TXT in the USB drive, you have it!

The Adafruit_nRF52_Bootloader for nRF52840 has a special MBR section at the beginning of the flash, ensure that the flash origin in memory.x starts with 0x00001000:

MEMORY { /* These values correspond to the nRF52840 WITH Adafruit nRF52 bootloader */ FLASH : ORIGIN = 0x00001000, LENGTH = 1020K RAM : ORIGIN = 0x20000008, LENGTH = 255K }

If you have a debug probe and don't want to use the bootloader, use the following memory.x config:

{ /* These values correspond to the nRF52840 WITHOUT Adafruit nRF52 bootloader */ FLASH : ORIGIN = 0x00000000, LENGTH = 1024K RAM : ORIGIN = 0x20000000, LENGTH = 256K }

Use debug probe

If you have a debug probe like daplink, jlink or stlink(stm32 only), things become much easier: connect it with your board and host, make sure you have installed probe-rs, then just run

cargo run --release

Then the command configured in .cargo/config.toml will be executed. The firmware will be flashed to your microcontroller and run automatically, yay!

Next Steps

Now you've finished the RMK's user guide. For the next steps, you can checkout features that RMK provides or explore how to configure RMK keyboard:

Supported FeaturesFeatures that RMK supports
ConfigurationExplore how to configure RMK keyboard