RTC2 continues to operate in Application after Bootloader execution

[Denis Shreiber]

Hello, Guys!

As I know, the Bootloader uses RTC2.

The problem is that RTC2 continues to operate after executing the bootloader, in my Application.

My Application not uses RTC2, and there is no any handler for RTC2_IRQn. When RTC2_IRQn happens the program freezes at Dummy_Handler.

After reset by Watchdog the RTC2 registers are cleared and the program runs well.

I solved my problem by executing this code at startup of my Application.

    uint32_t mask = NRF_RTC_INT_TICK_MASK     |
                    NRF_RTC_INT_OVERFLOW_MASK |
                    NRF_RTC_INT_COMPARE0_MASK |
                    NRF_RTC_INT_COMPARE1_MASK |
                    NRF_RTC_INT_COMPARE2_MASK |
                    NRF_RTC_INT_COMPARE3_MASK;

    NRFX_IRQ_DISABLE(RTC2_IRQn);

    nrf_rtc_task_trigger(NRF_RTC2, NRF_RTC_TASK_STOP);
    nrf_rtc_event_disable(NRF_RTC2, mask);
    nrf_rtc_int_disable(NRF_RTC2, mask);

I think my solution is not very good. Counting RTC2 in my Application is the consequence of executing bootloader.

Are you familiar with this problem? What would be a good solution?

I use SDK 16.0.0

[Hung Bui]

Hi Denis, 

When do you see that RTC kept running after the bootloader ? Was it on a normal booting or it's right after a DFU update ? 
As far as I know in SDK v16 (and newer) the bootloader will trigger a reboot after it receives the image. This reboot will reset all the peripherals that the bootloader uses including the RTC2. 
On a normal booting RTC2 shouldn't be running as the bootloader would go straight to the application. 

[Denis Shreiber]

The RTC2 keep running:

• After OTA DFU
• After downloading and running firmware via j-link
• After click Restart in debugger in SES
• After selfreset by NVIC_SystemReset()

The RTC2 is in reset state:

• After reset by PINRESET
• After reset by Watchdog
• If there are no Bootloader in internal flash

I did make some changes in Bootlodaer. May be this is a reason:

1. I enabled WDT by adding nrf_bootloader_wdt_init() to the first line in main

I attached sdk_config.h file of Bootloader

3583.sdk_config.h

[Hung Bui]

Hi Denis, 

Calling nrf_bootloader_wdt_init() will trigger the nrf_bootloader_wdt_feed_timer_start() which starts the RTC2 to feed the watch dog. This explain why you see the RTC active in many cases. 

What you can do is before nrf_bootloader_app_start() called in the bootloader, you can stop RTC2. This way you don't need to implement the code to stop RTC2 in your application. 

[Denis Shreiber]

Thank you, Hung!

I understood the root of the problem.

It would be nice if stop RTC2 was implemented in Bootloader in future releases of SDK