Flashing Firmware

The firmware can be flashed to your device either via a debug probe or via a bootloader.

Flashing via Debug Probe

The firmware can be flashed via a debug probe (e.g. CMSIS-DAP, ST-Link, J-Link) using the probe-rs tool. Before flashing, the debug probe has to be connected to the microcontroller and the host computer. Then the following command can be used to flash the firmware:

probe-rs run --chip <CHIP_NAME>

Lokey firmware projects usually also configure the cargo runner, which allows flashing the firmware using the following command as an alternative:

cargo run --release

Refer to the probe-rs documentation for more information.

Flashing via Bootloader

Flashing the firmware via a bootloader differs based on the microcontroller and the used bootloader. Below are instructions for some specific setups.

nRF52840 with UF2 Bootloader

If you are using the nRF52840 microcontroller with the Adafruit nRF52 bootloader, you can flash the firmware by following these steps:

• Compile your firmware to a .hex file using the cargo objcopy command from cargo-binutils.

  cargo objcopy --release -- -O ihex your_firmware.hex

• Convert the HEX file to a UF2 file using this python script:

  uf2conv.py your_firmware.hex --convert --family 0xADA52840

  0xADA52840 is the family ID of the nRF52840 microcontroller. Refer to the Adafruit nRF52 bootloader documentation for more information.

• Connect your nRF52840 microcontroller to your computer via USB.

• Put the nRF52840 into bootloader mode by double pressing the reset button. The device should appear on your computer as a USB drive with the file INFO_UF2.TXT in it.

• Copy the generated UF2 file to the USB drive. The bootloader will automatically flash the firmware and restart the device.