Implementing background DFU in app with writing own custom transport layer for Wi-Fi?

[vishal]

Hello,

We have implemented DFU services in application but getting lots of difficulties for writing own transport layer for Wi-Fi to upgrade firmware from server. We are using nRF52840 DK with SES and SDK15.3 version. I am trying to understand UART serial transport layer for the reference. 

Will you please help or guide me for writing own transport layer. In program when we sent GET request to server got first init packet buffer from server in responsive but how to pass this buffer to DFU using transport layer. Once init packet verification validate will send second GET request to server to get firmware image buffer from server. How pass this firmware image buffer to DFU in multiple packets request or Can I complete pass in one time?

Looking forward you help..

Thanks...!!!!

[bjorn-spockeli]

I am afraid that we do not have any guide on how to implement a custom transport layer for our DFU bootloader. 

If you are transferring the data received on WiFi to the nRF52832 over UART, then I recommend taking a look at the Serial Transport layer documentation, found here. We use the SLIP library  to encode the data and there are several Message sequence charts how to send the init packet and firmware packets. 

A FAE has also written a serial DFU host in C that you can take a look at. 

https://github.com/jimmywong2003/nrf-slim-serial-uart-dfu-host-c-code

Best regards

Bjørn