Too short range to perform DFU OTA

[Vincent RED]

Hello,

To contextualize my questions, here is my project : I am working on a mesh network with a proprietary protocol. Each node is stationary. I use the nRF52832 SoC.I use the Bluetooth DFU to perform OTA update.
However, for the moment I update node "manually", I switch one node in Bluetooth DFU mode, then I update it with the nRF Connect application then I repeat it for each node of my network.
As you suspected this operation is pretty long and really far to be optimized.
So I am trying to find a solution to automate it with the nrfutil cli.

Firstly I use the BL654 USB Adapter ( https://connectivity-staging.s3.us-east-2.amazonaws.com/2019-07/CS-PB-BL654-USB_NORDIC_ZEPHYR_v1_0.pdf ) but the range is really to short for my use. So I try with the nRF52832 Development Kit but I got the same range.
After some research, I noticed that the nRF52832 SoC is not compatible with Bluetooth Long range, so I try the OTA update with nRF52840 Development Kit and the Dongle previously quoted to have two devices able to use Bluetooth Long Range. Unfortunately I did not observe any improvement.

I also tried to use the mesh DFU protocol with the nRF52832 SoC. I followed the quick start ( https://infocenter.nordicsemi.com/index.jsp?topic=%2Fcom.nordic.infocenter.meshsdk.v3.1.0%2Fmd_doc_libraries_dfu_dfu_quick_start.html )
But after 10 minutes I have this error : Failed to upgrade target. Error is: Failed to establish connection

That makes a lot of issues that i can't solve.

Here are my questions :

The DFU protocol seems to be proprietary, is it possible that it limits the range of communication ? I try to perform DFU with and without antenna, there is no differences.

Even if the SoC and the soft-device we use is Bluetooth 5 qualified, does it use it ? Or does it use Bluetooth 4.0 or 4.1 ? Is it the same version for the Bluetooth DFU ?

Why DFU mesh in not add to the latest release of nrfutil ? Why it seems to be an abandoned tool ?

How to hard reset the BL654 USB Adapter ? I try to program only the original bootloader that I get from nRF at the end of the quick start but I have some key issue.

( https://devzone.nordicsemi.com/nordic/short-range-guides/b/getting-started/posts/nrf52840-dongle-programming-tutorial )


Thank you in advance,

Vincent.

[tesc]

Hi,

The mesh DFU from nRF5 SDK for Mesh is our proprietary solution, yes. It communicates similarly to Bluetooth mesh, which is based on Bluetooth 4. Range is extended through messages being relayed through the mesh network, which means communication will break if the longest "hop" gets too large. The reason why mesh DFU uses an "old" version of nrfutil is this is a different solution than our "normal" DFU over BLE, and for the mesh solution nrfutil was forked. That means there are two versions of nrfutil - each with their own versioning - one for mesh DFU and one for BLE DFU.

Regarding the dongle from Laird, I am not familiar with that one as it is a third party product. If it is similar to the nRF52840 Dongle then you can follow the programming tutorial that you posted a link to. If they use a different DFU bootloader, or if they have different hardware, then you need to consult documentation and support from Laird.

Regards,
Terje

[Vincent RED]

Hi,

Thank you for your answer, that help me a lot.
The mesh DFU look like the best way to perform OTA update in my case but I was afraid that the tool was not maintain anymore. Your answer gives me comfort.

I still cannot explain why there is no range increase when I perform DFU over ble with or without antenna. If you have a part of the answer it would be nice.

As I will focus on mesh DFU, I allow myself to ask about the error I get.
I have seen some similar issue in other tickets, the solution was to use an other version of the bootloader and the softdevice, what I tried without improvements.
Tell me if you need more details or if it is more suitable to create a dedicated ticket.

Thanks a lot,
Regards,

Vincent.

[tesc]

Hi,

What do you mean by "perform DFU over BLE with our without antenna"? Both the Dongle form Laird and the DK does use an antenna, although most likely a different kind of antenna due to different space constraints. I would not expect a big difference in range between them.

Regarding the Mesh DFU error message, please open a new thread for that. Then that thread can concentrate on that issue alone, and this be more general about OTA DFU options and range implications.

Regards,
Terje

[Vincent RED]

Hi,

By "perform DFU over BLE with or without antenna" I mean with an external antenna which is supposed to increase significantly my range. Sorry for the vagueness.
I already explore the impedance clue and I am pretty sure my antenna is tuned with 50 Ohm

I will open a new thread for my mesh DFU issues, thanks for your help.

Regards,

Vincent

[tesc]

Hi,

The PCB antenna on the board should already give a fairly good range, as we always tune the antenna and matching network for our DKs. What range are we talking about? For instance if you see issues with anything less than 10 meters and line of sight then there is definitely something other than the antenna. What is the desired, and what is the actual, range that you see?

Regards,
Terje