How to do DFU on BLE central devices?

RE: How to do DFU on BLE central devices?

Einar Thorsrud — Fri, 05 Nov 2021 07:35:24 GMT

Hi,

[quote user="researcher"]Even though USB 2.0 is available in nrf52833, Secure DFU Bootloader over USB is pointing DFU over USB (USB CDC ACM) is available only on nrf52840. I am bit confused.[/quote]

That is just because we do not provide all examples for all boards, as that would greatly increase the size of the SDK etc. But you can adapt examples for other boards without too much effort.

The PCA10056e projects are for nRF52811. The PCA10100 projects are for the nRF51833 DK. However, in any case migrating an example from one DK and IC to another is normally not that much work.

The nRF52840 and nRF52833 are very similar, so porting projects between these ICs is quite straightforward. In addition to the general things you need to remember when changing IC variant (linker configuration of flash and RAM sizes, defines that specify IC variant and board), you also need to change nrf_crypto backend from CC310, as that is only available on nRF2840. For the latter reason I think it makes more sense to start with the pca10100e sample, as that exists for USB. So, I suggest you take the example from <SDK>/examples/dfu/secure_bootloader/pca10100e_usb/.

RE: How to do DFU on BLE central devices?

researcher — Fri, 05 Nov 2021 02:32:09 GMT

Hi Einer,

Thanks a lot for the information.

Ok, DFU over USB is nice option. We are using nrf5 SDK 17.

But <InstallFolder>\examples\dfu\secure_bootloader\pca10040e_uart is only available at SDK for nrf52833. I could not see the DFU over USB example for nrf52833 at SDK.

Even though USB 2.0 is available in nrf52833, Secure DFU Bootloader over USB is pointing DFU over USB (USB CDC ACM) is available only on nrf52840. I am bit confused.

RE: How to do DFU on BLE central devices?

Einar Thorsrud — Thu, 04 Nov 2021 17:54:07 GMT

Hi,

[quote user="researcher"]Yes, It is dongle and nrf52833's USB 2.0 lines are always connected to PC. Actually, can i do DFU through this USB?[/quote]

Yes, you can. For a USB connected dongle that makes the most sense. We provide a USB DFU solution out of the box. Which SDK are you using for your development? If you are using the nRF5 SDK, then see Secure DFU Bootloader over Serial Link (UART/USB). In your case, USB is what is relevant and not UART, as that is what you already have as a communication channel between the PC and the nRF.

[quote user="researcher"]Does it need jlink debugging tool for making DFU over UART? i[/quote]

No, there is no need for a J-Link debugger, and also no UART. It is simply using USB communication between the PC and the dongle.

[quote user="researcher"]2. In DFU over BLE, How to switch the central device from the application to DFU mode? This dongle will not advertise while application is running, then how can i switch to DFU mode using 'nrf connect' android application? [/quote]

You need some application specific way of telling your dongle that it should enter DFU mode. How that is depends on what fits your product. When that happens, you use a few lines of code to enter DFU mode. That happens by resetting into the bootloader, which is configured to always act as a peripheral. And you would need a BLE central to connect to it to perform the DFU.

RE: How to do DFU on BLE central devices?

researcher — Thu, 04 Nov 2021 15:29:06 GMT

Hi Einar,

Thank you for making me to look at that DFU over UART is available on nrf52833.

Yes, It is dongle and nrf52833's USB 2.0 lines are always connected to PC. Actually, can i do DFU through this USB? Does it need jlink debugging tool for making DFU over UART? if so, i have to think about DFU over BLE.

2. In DFU over BLE, How to switch the central device from the application to DFU mode? This dongle will not advertise while application is running, then how can i switch to DFU mode using 'nrf connect' android application?

Thank you for your assistance and kind helping

RE: How to do DFU on BLE central devices?

Einar Thorsrud — Thu, 04 Nov 2021 11:59:32 GMT

Hi,

As this is a dongle I would think perhaps DFU over USB would be relevant? If so that is demonstrated by the DFU bootloader examples in the SDK (which also demonstrate other transports like BLE and UART).

Or do you intend to use DFU over BLE? If so, what will be the DFU master in this case? Generally I would suggest that even if the device is normally central it could switch to being a peripheral while doing DFU. That way you can use the existing BLE DFU bootloader example, which is a BLE peripheral. The device could still act as a central only in the application.