DFU Peripheral to Central?

[Arepa]

Hi all

Is possible have DFU in the peripheral side to update a Central app program? Is there example doing it?

I have a Peripheral (custom board nRF52 dongle) connected to a PC, and I want to update the application program in the Central side (remote battery powered) using DFU.

Is possible to do a DFU Periphera-to-Central role instead of Central-to-Peripheral?

Thanks

[Hung Bui]

Hi Arepa,

Does it have to be the remote device running in central mode when you are doing DFU ?

We currently don't have an example for that.

But please be noted that the S132 is capable of running in both central and peripheral. So there is an option that you run your device in central mode, then you send a command from the peripheral connected PC that the remote device switch to bootloader and starts as a peripheral. You then can also switch the peripheral into central mode to do DFU update.

With this solution you only need to make the DFU master part which run on the PC. (We don't have this part yet). Alternatives are you can update using a phone or from PC via nrfutil tool (if you run the dongle with connectivity firmware).

If you really have to keep the remote device in central role, then you need to implement your own bootloader. You can reuse many parts from the default bootloader, you can set up a GATT server on the central side and receive image to that server. Only difference here is the DFU master advertise, the DFU target connects instead of the other way around.

[Hung Bui]

Hi Arepa,

Actually it's the opposite, the central usually consume more power consumption. The central usually have to listen most of the time, and staying in RX mode can consume even more than when transmitting.

Note that the peripheral only need to switch to TX mode when it want to send something, and this can be very short period in time.

So, usually the central should be the one more power hungry than the peripheral. You should consider running the device connect to PC in central mode.

Regaring the DFU master, we don't have an example that you can run the DFU master on the nRF52 directly as a central. The example we have, as described, to have connectivity firmware on the nRF52 and all the code running on the PC. You can have a look at the source code of nrfutil on github as the reference code.

Other source is to have a look at the code of DFU library in NRFToolbox app for Android/iOS. But the best is just to follow the documentation of the DFU protocol in the SDK on Infocenter.

How do you plan to send data from your PC to your nRF52 connected to PC ? Do you have plan to simply use connectivity firmware on the nRF52 and then use BLE driver to control it from PC. It's then much easier to do DFU that way. You still can use PC to create a normal peripheral. There are several example provided. Have a look here.