Hardware SPI DFU from one nRF52840 to another nRF52840.

[kfci-eng]

Hello,

I was wondering if there is away to perform DFU using SPI without smp protocol or mcumgr from one nRF52840 to another? What I am trying to do is to send a firmware image (.bin file) from one chip to another via SPI, and then have MCUboot update the image on the receiving chip. Is there a way to do this? So far, I have been able to enable MCUboot on the kits, generate a private key to sign images and also flash them using visual studio code. All the samples I have found of serial dfu use a shell or some other tool, but I want to replace this with SPI protocol. Is it possible? Any guidance will be greatly appreciated.

*I am aware that this could be done via BLE and that there are samples for this, but eventually I would want to update the nRF52840 from another MCU via SPI, so I want to test with two nRF52840 first. 

BR,

Kevin 

[Marte Myrvold]

Hi Kevin,

It should be possible to perform DFU over SPI, but we do not have any guides or information on how to do this. One option is to use SMP and implement the SPI transport layer yourself, but this will require work on your side.

A colleague has made some unofficial bootloader samples that you can take a look at: https://github.com/hellesvik-nordic/samples_for_nrf_connect_sdk/tree/main/bootloader_samples. You can find examples of performing DFU from one nRF52840 DK to another using BLE there. The samples use the Zephyr mcumgr driver for transport, so you would only need to implement the SPI transport layer once. Please note that these examples are unofficial and provided as-is.

Best regards,
Marte

[kfci-eng]

Hi Marte,

Thank you for your reply. I went over the sample but it is challeging to me to understand how I could modify or change the sample to use SPI as the transport layer. Is there any sample that performs DFU from one DK to another using Hardware UART (No USB, shell, etc). I think that would be very helpful. I have been looking on the devzone and on the ncs github but haven't found any.

Best,

Kevin

[Marte Myrvold]

Hi Kevin,

The method I mentioned in my previous reply uses mcumgr-lib. In this case, you must implement the transport for both the SMP client and the SMP server. I would recommend taking a look here: https://github.com/nrfconnect/sdk-zephyr/tree/main/subsys/mgmt/mcumgr/transport. Additionally, you can also look at this unofficial sample: https://github.com/hellesvik-nordic/samples_for_nrf_connect_sdk/tree/v2.2.0/bootloader_samples/client_smp/smp_client_uart. It is a modified version of the sample in my previous reply, and it uses UART instead of Bluetooth as transport.

The other option is to use the DFU target library. With this, you can implement the SPI however you like on the client and use the DFU target library on the server side to handle the image received over SPI.

Best regards,
Marte

[kfci-eng]

Hi Marte,

Thanks! I will follow that recommendation and use the DFU target library directly, I have been reading the API documentation. I appreciate your help!

Best regards,

Kevin