A question about ota

Question

Hi, all!
I am rencently studying ota,and that is what I have done: 
 
 Program softdevice 6.0 into my nrf51822 chip. 
 Program bootloader(version in SDK5.2) into my nrf51822 chip. 
 Use Nrf_TooBox app to upload an application into my nrf51822 chip by means of OTA. 
 
 So far the OTA is finished.But I got the further question: 
 If the application I upload into my chip is a normal application without the function of DFU(like ble_app_hrs), how could the chip be able to go back to the bootloader again and then run the ota again?
If possiable,please tell me what I should do in deteils. 
 Looking forward to your reply. Thank you very much!

kk · Accepted Answer

I think I got the right answer after reading the similar question in forum.
And my solution is: 
 
 
 about application code,just set the NRF_POWER->GPREGRET=1 and on power reset the chip is enough: 
 sd_softdevice_disable(); 
 NRF_POWER->GPREGRET = 1;
 NVIC_SystemReset();
 
 
 
 or just use 
 sd_power_gpregret_set(1);
 
 if you don't disable the softdevice; 
 
 about bootloader, set the NRF_POWER->GPREGRET=0 is enough: 
 
 replace the code like this: 
 uint32_t a;
 sd_power_gpregret_get(&a);
 if (bootloader_is_pushed || (!bootloader_app_is_valid(DFU_BANK_0_REGION_START)) || (a == 1))
 {
 nrf_gpio_pin_set(LED_2);

 sd_power_gpregret_set(0);

 // Initiate an update of the firmware.
 err_code = bootloader_dfu_start();
 APP_ERROR_CHECK(err_code);

 nrf_gpio_pin_clear(LED_2);
 }
 
 If something is wrong or missing, please point it out.
Thank you very much!