Serial DFU bootloader for electronut labs bluey
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hex update binaries Jul 22, 2017

nRF52832 HCI/UART DFU Bootloader - From nRF5 SDK v11.0.0

Device firmware update (DFU) bootloader which allows the nRF52832's firmware and/or SoftDevice to be updated serially.

nrfutil v0.5.2 can be used to transfer a firmware image from computer to nRF52832.

To enter the bootloader, press and hold button1 on bluey and then press and release RESET button -- must be held low on startup or reset. The Blue LED will blink in a "timebomb" pattern to indicate the board is in the bootloader state.

For more information on the Nordic BLE & HCI/UART Bootloader/DFU, check out their SDK Reference Page.


  • /config -- Platform-specific configurations.
  • /hex -- Compiled hex files for the SoftDevice (S132) and bootloader.
  • main.c -- Main source file for bootloader application

Toolchain Requirements

To compile this bootloader, you'll need armgcc and Nordic's nRF5_SDK_V11.0.0.

Documentation for the nRF5 SDK (v11.0.0) can be found at Follow along with the instructions there to install and set up the SDK. Note that GCC is used instead of Keil or IAR.

Building the Bootloader

Before building the bootloader, open the Makefile and modify SDK_PATH (line 4, setting the relative path to the top-level path of your Nordic SDK.

Once that is set, open this "bootloader-custom" folder in a command terminal and type make. sfe_nrf52832_dfu.hex should be created in a "_build" folder, which can be uploaded to the Bootloader section of the nRF52832's flash.