How to detect cause of Reset

Question

Hello,

I am using nRF52832, SDK_15.3.0, S132 SoftDevice and Segger for flashing the image. I am using ‘ble_app_blinky’.

1) As per below link, do I need to skip GPIO initialization when chip wakeup from System OFF or even peripheral, ble and other initializations (Ex: rtc, timers etc…) can be skipped.

https://devzone.nordicsemi.com/f/nordic-q-a/38550/gpio-value-after-wake-up-from-gpio

2) Is there any API to know the status of reset (System OFF, Watchdog etc…) or directly read NRF_POWER->RESETREAS register.

3) As per below link, I am trying to print RESETREAS register. But code gets hanged. Do I need to call NRF_POWER->RESETREAS before enabling of SoftDevice.

https://devzone.nordicsemi.com/f/nordic-q-a/38405/detect-wake-up-reason-from-deep-sleep/148200#148200

    #if 1
    uint32_t u32Reset_reason = NRF_POWER->RESETREAS;
    NRF_LOG_INFO("Reset Status %x", u32Reset_reason);
    NRF_POWER->RESETREAS = NRF_POWER->RESETREAS; // Clear reset reason by writting 1.
    #endif

I called above code after all Peripheral and SoftDevice initilization. But I am getting below debug prints.

<info> app: Reset Status 0

<error> app: SOFTDEVICE: INVALID MEMORY ACCESS

Thanks & Regards

Vishnu Beema

cbd · Accepted Answer

You'll certainly need to reinitialise the SoftDevice and your BLE. 
 Personally I prefer to run through as much initialisation as possible, but depending on your application there may be things that you skip e.g. GPIO lines that you set to specific states before power off, that you wish to retain their state without interruption on power-up. 
 Anything reliant on RAM will need to be initialised on restart from System OFF as its not retained unless you've set it to remain powered through use of RAM[n].POWER registers on shutdown.

Jimmy Wong · Answer

Hi, 
 You can store the err_code on the flash (particular region) inside the app_error_handler. 
 https://github.com/jimmywong2003/nrf5-debug-save-error-code-flash-app 
 void app_error_save_and_stop(uint32_t id, uint32_t pc, uint32_t info)
{
...
 case NRF_FAULT_ID_SDK_ERROR:
 m_error_data.p_error_info = (error_info_t *)info;
 m_error_data.err_code = m_error_data.p_error_info->err_code;
 m_error_data.line_num = m_error_data.p_error_info->line_num;
 m_error_data.p_file_name = m_error_data.p_error_info->p_file_name;
 path_addr=(uint32_t *)m_error_data.p_error_info->p_file_name;


 // Erase page:
 flash_page_erase(flash_addr);
 flash_word_write(flash_addr, m_error_data.err_code);
 flash_addr++;
 flash_word_write(flash_addr, m_error_data.line_num);
 flash_addr++;
 for(store_length=0; store_length<1000;)
 { 
 When you print out the reset reason (NRF_POWER->RESETREAS) after just system power up, 
 
 if the reset reason is 0, most likely it is caused by the POR (Power on reset ) or BOR (Burst on reset). 
 If it is non-zero value, you can refer to the table as below (inside the Product specification).

How to detect cause of Reset

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