Thread Secure DFU

[xiang san]

Hi,

I have a question about 'Thread Secrue DFU',according to the 'https://infocenter.nordicsemi.com/index.jsp' ,the 'Thread Secrue DFU'  does not use softdevice of transform components, So does it support multi protocol  OTA DFU? example Ble_Thread protocol，because the Ble will used softdevice.

[Jørgen Holmefjord]

Hi,

That is correct, the softdevices are only used for BLE (and ANT) protocols. The Thread stack (OpenThread) is delivered as a linkable library in the nRF5 SDK for Thread and Zigbee, and is also available as source code on GitHub.

The Thread Secure DFU solution uses the Thread protocol to transfer the DFU image to the device. This transfer happens in the application, and a bootloader will handle the swap to new firmware when the entire package is deceived. This solution requires the device to store two separate firmwares at the same time (dual bank DFU), which means that the available size for DFU firmware is ~half of the flash size of the device (some will flash pages will be used for storing bootloader/MBR). If you want to have a multiprotocol application with both BLE and Thread, the softdevice will also require some space in flash, limiting the size available for the rest of the application even further.

Do you also want to support DFU over BLE in the bootloader, or do you want DFU to happen over Thread, but the application to support both Thread and BLE? We do not have any examples showing this, but I'm sure that the bootloader/application examples can be extended to support this, even though the maximum supported size for the application will be quite small, event in nRF52840 IC with 1MB flash.

Best regards,
Jørgen