Buttonless Secure DFU with WDT needs DFU twice

Question

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 · Accepted Answer

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
");

 // 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.

Buttonless Secure DFU with WDT needs DFU twice

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