Ability to restart DFU when interrupted while in DFUTarg

[QuentinFarizon]

Sometimes during a DFU update, the NRF52811 can stay in bootloader mode (seen with name DFUTarg and mac_address equal tomac_address+1).
I am on Softdevice 16.0
I'm using the https://github.com/NordicSemiconductor/Android-DFU-Library.

To be able to resolve this situation, I imagine that it would be possible for this DFU library to recognize a previous DFU process failed, and restart the DFU process from here.

I have tried setting initiator.setNumberOfRetries(1) but it did not help.

Is there something I'm missing ? How can I implement this myself ? As I can connect to the mac_address+1, is there a command I can send to make it restart on normal mode ?

[Einar Thorsrud]

Hi,

There is not DFU command to exit DFU and reset the application. However, the bootloader has a timeout which is configured by NRF_BL_DFU_INACTIVITY_TIMEOUT_MS in the bootloader's sdk_config.h. This is set to 2 minutes (120000 ms) in most bootloader examples in SDK 16. So if there are more than 2 minutes of inactivity the bootloader will start the app if a valid app is present. If no valid app is present (typically if having started a single bank update), the only way to recover is to perform a successful DFU update.

[QuentinFarizon]

Indeed, I do not have NRF_BL_DFU_INACTIVITY_TIMEOUT_MS set.

When you say "the only way to recover is to perform a successful DFU update." => how can we perform a successfulDFU update when in this state ?

[Einar Thorsrud]

Hi,

QuentinFarizon said:

When you say "the only way to recover is to perform a successful DFU update." => how can we perform a successfulDFU update when in this state ?

That depends on which state the device is in, which is not entirely clear to me. What DFU master are you using? If you are testing for nRF Connect, then you can get a log which may give some relevant information. Any other information about when/how update fails will also be useful.

[QuentinFarizon]

I'm using an ionic library that uses https://github.com/NordicSemiconductor/Android-DFU-Library under the hood.

I'm not exactly encountering an issue with real uses, but I try to see if the DFU process is resistant to connection loss, loss of power, ... before allowing users to perform DFu themselves on the field.

I will try with NRF_BL_DFU_INACTIVITY_TIMEOUT_MS, if there is a loss of power during upload, it should restart with the previous application right ? 

[QuentinFarizon]

But I'll still have the issue of my previously distributed PCBs. In the state they are when interrupted, they are on bootloader on DFUTarg, but previous application should still be there. How can I just restart it on the previous application ?

[Einar Thorsrud]

Hi,

QuentinFarizon said:

I'm using an ionic library that uses https://github.com/NordicSemiconductor/Android-DFU-Library under the hood.

I see. Then I suggest you test with nRF Connect just to obtain the the log if needed.

QuentinFarizon said:

I'm not exactly encountering an issue with real uses, but I try to see if the DFU process is resistant to connection loss, loss of power, ... before allowing users to perform DFu themselves on the field.

Then it would also be useful to test with the debug bootloader with RTT logging to understand what happens on the bootloader whenever you see an issue of some sort.

QuentinFarizon said:

I will try with NRF_BL_DFU_INACTIVITY_TIMEOUT_MS, if there is a loss of power during upload, it should restart with the previous application right ? 

Yes. But that of course depends on the presence of a valid application. If the existing application has been removed allready because of a started single bank update of the app or SoftDevice/BL update, then there will not be any valid app to boot.

[QuentinFarizon]

Even withtout a valid app to boot, the bootloader should be OK. Is it not possible to perform a new DFU process, with the bootloader already in DFU mode ?

[Einar Thorsrud]

QuentinFarizon said:

Even withtout a valid app to boot, the bootloader should be OK.

Yes.

QuentinFarizon said:

Is it not possible to perform a new DFU process, with the bootloader already in DFU mode ?

That should not be any problem. (Though it seems like it is in your test, which is why I suggested to get logs to understand what is going on.)