RE: Buttonless Serial DFU Example on NRF52840-DK

Vidar Berg — Mon, 11 Nov 2019 10:47:24 GMT

Hi,

We don't have a buttonless template example for UART DFU. But there are several ways to signal the bootloader to enter DFU mode. The easiest way is maybe to write the BOOTLOADER_DFU_START flag to NRF_POWER->GPREGRET (use sd_power_gpregret_set if SD is enabled) followed by an NVIC_SystemReset(). The bootloader will enter DFU mode on the next startup as long as it has been compiled with the NRF_BL_DFU_ENTER_METHOD_GPREGRET config enabled. Alternatively, if the reset pin is connected to the host CPU, you can enable the NRF_BL_DFU_ENTER_METHOD_PINRESET option and assert the reset line whenever you want to enter DFU mode.

You can try the UART bootloader without flow control to verify the stability at the baud rate you wish to use. The BLE transport should not impact the performance if you disable it once DFU is initiated on the serial transport.

Best regards,

Vidar