Buttonless Secure DFU with WDT needs DFU twice

[kamisen]

I use nrf51822xxAC，SDK 12.2，Buttonless Secure DFU and WDT in application.

I added NRF_WDT->RR[0] = WDT_RR_RR_Reload; to the wait_for_event loop in the DFU to pet the dog.

But it needs to DFU twice to let the chip run into application.

The same question in this link.

Could anyone help me?

[Hung Bui]

Hi Kamisen,

I'm sorry indeed for late response. I was occupied by something else and forgot to get back to the case.

I checked again, it seems that if we only put the NRF_WDT->RR[0] = WDT_RR_RR_Reload; inside wait_for_event() it's not enough as after we receive the image and then do swapping it may last longer than 2 seconds ( i tried 10seconds and it worked) and cause a WDT reset. What you can do is to put the NRF_WDT->RR[0] = WDT_RR_RR_Reload; also inside the while loop in nrf_dfu_app_continue() in nrf_dfu_utils.c like this:

NRF_LOG_INFO("Enter nrf_dfu_app_continue\r\n");

    // Copy the application down safely
    do
    {   NRF_WDT->RR[0] = WDT_RR_RR_Reload;

        cur_len = (length_left > split_size) ? split_size : length_left;

Please try and let me know if it fix the issue for you.

[kamisen]

Thanks a lot. I think you can update your Secure DFU blog with the WTD handle. ;-)

[Hung Bui]

Good to know it worked. Thanks for the tip, I will update my blog.

[Guillaume LS]

You will face the same watchdog issue if you try to update the SoftDevice. I think the same fix has to be applied also in the nrf_dfu_sd_continue_impl() function.