DFU in nRF52820 using nRF connect SDK

[khodidas]

Hi,

We need to add DFU over BLE support to our nRF52820-based project. We have developed our application firmware using nRF connect SDK v2.1.2.

We have successfully added MCUboot + SMP support in one of our project which is based on nRF52840 and DFU over BLE is working fine in it.

But the same MCUBoot configuration we have used in this nRF52820-based project, but in this, we are facing a memory issue. Flash/RAM are overflowing. We have optimized our application, but still, it is using 80% of the flash memory. 

How can we add DFU over BLE support in our project? 

Is it possible to add/perform single bank DFU in MCUboot like we have in nRF5 SDK bootloader? 

Br,

Narendra

[Marte Myrvold]

Hi Narendra,

It is possible to use only one image slot for MCUboot by setting the CONFIG_SINGLE_APPLICATION_SLOT option. Please be aware that when using single slot bootloader the new application will overwrite the current application, and if there is something wrong with the new application you will not be able to revert back to the previous one.

Another option is to use external flash for the secondary slot, as explained in Using external flash memory partitions.

Best regards,

Marte

[khodidas]

Hi Marte,

Thanks for the answer.

I have tried with CONFIG_SINGLE_APPLICATION_SLOT=y, but it shows an undefined symbol. 

On searching Devzone about this, found that it is not supported for DFU over BLE..Please have look at below post,

 Single slot DFU using MCUBoot 

Can we use nRF connect secure bootloader with a single bank in place of MCUBoot?

Thanks,

Narendra

[Marte Myrvold]

Hi Narendra,

You are correct that you can only use single slot DFU over serial, and not over Bluetooth Low Energy. If you want DFU over Bluetooth you need to use external flash.

Best regards,

Marte

[Eirik Aa]

But that makes the whole DFU process on a nRF52820 running Zephyrus kind a useless? Or is there another way do do this?

[Kenneth]

Hello,

Have in mind that the bootloader should not take up much space, so it's tradeoff here. Also for your second question (DFU over BLE vs. external flash), this can likely be avoided by using an nRF52 variant with more flash space (e.g. nRF52840).

Kenneth