RE: [nRf52840] Update firmware from external flash

Edvin — Tue, 12 Jan 2021 13:42:23 GMT

Hello,

[quote user=""] I cannot rely on single bank OTA.[/quote]

Please note that signel bank does not brick the device. It only means that if something happens during the DFU (runs out of battery or goes out of range), then the device will be stuck in DFU mode until it is updated again.

If you still wish to use an external flash, then this is something you need to implement. I would recommend that you start with one of the serial bootloaders, such as the SDK\examples\dfu\secure_bootloader\pca10056_uart_debug, (use _debug for development, and when you are done, apply the same changes to the non- _debug project).

The bootloader in the SDK is a passive bootloader. This means that by default, the bootloader will wait for the application being pushed to it while it is in DFU mode. In your case, that is not possible, so you would have to implement something that actually reads the application from the external flash, and performs the DFU. Look at how the event NRF_DFU_OP_OBJECT_EXECUTE is implemented, which I believe is the command that is sent when the transfer of the new image is done, which will actually move and replace the existing application.

Best regards,

Edvin