DFU from iPhone SE fails

RE: DFU from iPhone SE fails

Einar Thorsrud — Thu, 21 Jan 2021 11:23:42 GMT

Hi,

Good to hear. I cannot see any reason why you should see this issue again with PRN set to 1.

RE: DFU from iPhone SE fails

sjerlhagen — Wed, 20 Jan 2021 16:52:43 GMT

Yes, it is a 2020 iPhone SE with iOS 14.2, nrfconnect is version 2.4.6 build 10.

Reducing PRN to 1 in nrfconnect helps, is this a reliable solution ? PRN=2 did not work.

RE: DFU from iPhone SE fails

Einar Thorsrud — Wed, 20 Jan 2021 15:16:45 GMT

Hi,

[quote user="sjerlhagen"]So far we are using the ios nrfconnect app. [/quote]

I see. Then there is no way you can tweek this.

[quote user="sjerlhagen"]Do you mean NRF_SDH_BLE_GATT_MAX_MTU_SIZE 23 in the bootloader ?[/quote]

You can do it in the bootloader, yes. And it would be a good test to see if it works. But my original thought was to do it in your app, assuming it was a custom app (which I now understand is not the case).

[quote user="sjerlhagen"]What is PRN ?[/quote]

This is Packet Receipt Notification, which is a concept in the DFU protocol. It can be used as a form of flow control mechanism.

I assume this is the 2020 version of the iPhone SE, right? Which version of iOS and nRF Connect are you using?

RE: DFU from iPhone SE fails

sjerlhagen — Wed, 20 Jan 2021 14:37:49 GMT

So far we are using the ios nrfconnect app. The flash write requests are queued and use separate write buffers, so it shouldnt be a problem if some writes take a long time, but you are right, this is the problem.

Do you mean NRF_SDH_BLE_GATT_MAX_MTU_SIZE 23 in the bootloader ?

What is PRN ?

RE: DFU from iPhone SE fails

Einar Thorsrud — Wed, 20 Jan 2021 12:32:49 GMT

Hi,

Are you using a custom app to do the DFU? And are you using the IOS-Pods-DFU-Library library?

We have seen such issues from time to time, and often it is if data arrives too fast compared to the time it takes to write to flash. Typically this can be solved by reducing the BLE packet size (say down to 23) and/or using PRN with a lower number.