The Open Bootloader example uses the Bootloader and DFU modules to implement a bootloader with Device Firmware Update (DFU) functionality. Open bootloader has relaxed security compared to the Secure Bootloader .

• Application update may come from an unsigned package ( NRF_DFU_REQUIRE_SIGNED_APP_UPDATES ).
• SoftDevice update may come from an unsigned package if the bootloader does not depend on the SoftDevice ( NRF_DFU_REQUIRE_SIGNED_APP_UPDATES ).
• Bootloader update must come from signed packages.
• Single-bank updates are preferred ( NRF_DFU_SINGLE_BANK_APP_UPDATES ).
• Firmware version get command is supported ( NRF_PROTOCOL_FW_VERSION_MSG ).

The open bootloader example ( examples/dfu/open_bootloader ) is provided only with USB CDC ACM DFU Transport .