Firmware Update over UART Interface

[Jatala]

Hello,

Background: I have a custom board that contains nRF52832 module and exposes UART pins (RX, TX, RTS, CTS). I have developed an application using nRF5 SDK v17.0.2. The application does not use any so -called SoftDevice.

Objective: I want to develop a mechanism to update the application firmware of on the nRF52832 module over the UART interface from another micro-controller.

Seeking Help: After searching through the SDK and the forum, it looks like I have to use libraries under Bootloader and DFU modules But I am still confused which components to use and in what order. On the nRF52832 module, do I need to program, as part of my application, routines to receive and process DFU commands/data packets. I am also using the same UART port to exchange application data (from sensors attached sensors )  with the other micro-controller.

I would appreciate any help that can get me started on the right path to achieve the objective.

[Jatala]

Thanks. There are two examples pca10040_uart and pca10040e_uart  in ../examples/dfu/secure_bootloader.  I assume they both are exactly same except that the latter use easy DMA. Could you please confirm.

[Hung Bui]

The PCA10040e is for nRF52810 emulation on PCA10040, you can have a look here.

[Jatala]

That is new information for me, thanks.

It appears that the UART port pin assignment, configuration and registration as DFU transport are handled in ../components/libraries/bootloader/serial_dfu/nrf_dfu_serial_uart.c.

[Hung Bui]

I would suggest to test the bootloader with nRFutil on PC first to get familiar to it before you move to other tasks. 

[Jatala]

Hi Hung,

For switching to the bootloader, the APIs (sd_power_gpregret_clr, sd_power_gpregret_set) to write to the retention register GPREGRET are part of the SoftDevice library.  That means I must flash SoftDevice in my board. Alternative is to use NRF_POWER->GPREGRET available in nrf52.h that will not require me to use the SoftDevice. Seems I am on the right track?