RTC fails to wake chip from SystemON Sleep nrf52840

RE: RTC fails to wake chip from SystemON Sleep nrf52840

ovrebekk — Tue, 18 Aug 2020 07:23:12 GMT

Hi Conner

[quote user="EMPConner562"]This is this first time i'm posting about the issue?[/quote]

Seems so, yes. My point is that I can't remember anyone else posting about similar issues either, so it's not a known issue to us.

[quote user="EMPConner562"]One other thing that I've since found out is that the ones in production were programmed with the nRFgo Studio, with Read back protection enabled. These are the devices that appear to have failed.[/quote]

This might explain it. nRFgo Studio is very old, and is not recommended for use with the nRF5 series. I would strongly suggest using nrfjprog instead, and make sure you have up to date JLink drivers.

[quote user="EMPConner562"]I also enabled read back protection in the following way in code:[/quote]

When writing to the flash it is important to check the state of the READY register before and after each operation. For reference I have included a code snippet from the system_nrf52840.c file to illustrate this:

#if defined (CONFIG_GPIO_AS_PINRESET)
    if (((NRF_UICR->PSELRESET[0] & UICR_PSELRESET_CONNECT_Msk) != (UICR_PSELRESET_CONNECT_Connected << UICR_PSELRESET_CONNECT_Pos)) ||
        ((NRF_UICR->PSELRESET[1] & UICR_PSELRESET_CONNECT_Msk) != (UICR_PSELRESET_CONNECT_Connected << UICR_PSELRESET_CONNECT_Pos))){
        NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Wen << NVMC_CONFIG_WEN_Pos;
        while (NRF_NVMC->READY == NVMC_READY_READY_Busy){}
        NRF_UICR->PSELRESET[0] = 18;
        while (NRF_NVMC->READY == NVMC_READY_READY_Busy){}
        NRF_UICR->PSELRESET[1] = 18;
        while (NRF_NVMC->READY == NVMC_READY_READY_Busy){}
        NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Ren << NVMC_CONFIG_WEN_Pos;
        while (NRF_NVMC->READY == NVMC_READY_READY_Busy){}
        NVIC_SystemReset();
    }
#endif

Best regards
Torbjørn

RE: RTC fails to wake chip from SystemON Sleep nrf52840

EMPConner562 — Mon, 17 Aug 2020 08:27:56 GMT

Hello,

This is this first time i'm posting about the issue?

The battery is soldered in, so I've removed and then re-soldered the battery and the device didn't start working again, with the one i tested.

The voltage on the batteries is close to the nominal 3V.

This is the RTC handler code:

static void rtc_handler(nrf_drv_rtc_int_type_t int_type)
{
    if (int_type == NRF_DRV_RTC_INT_COMPARE0)
    {
       nrfx_clock_hfclk_start();
       gpio_check_and_esb_tx();
       nrf_drv_rtc_counter_clear(&rtc);
       nrf_drv_rtc_cc_set(&rtc,0,COMPARE_COUNTERTIME * 8,true);
    }
}

One other thing that I've since found out is that the ones in production were programmed with the nRFgo Studio, with Read back protection enabled. These are the devices that appear to have failed. I also enabled read back protection in the following way in code:

    if (NRF_UICR->APPROTECT != 0x0)
    {
    NRF_NVMC->CONFIG = 0x1;
    NRF_UICR->APPROTECT = 0x0;
    NRF_NVMC->CONFIG = 0x0;
    }

I have setup a test to see if enabling the read back protection in nRFgo Studio has any affect on the crash. I have programmed three devices one with segger, one with nRFgo without the read back protection, and one with nRFgo Studio with read back protection.

After letting these run from Wednesday, I have checked them again today and only the one programmed with nRFgo Studio with read back protection has stopped working. This could be a coincidence however I now believe this to be the issue.

Is there any reason that you can think of that this might cause such an issue?

Kind regards

Conner

RE: RTC fails to wake chip from SystemON Sleep nrf52840

ovrebekk — Fri, 14 Aug 2020 07:05:18 GMT

I can't remember seeing reports of this issue earlier.

Does it start working again if you remove and re-insert the battery?

What is the voltage over the batteries?

Could you show me how the RTC interrupt is handled?

Best regards
Torbjørn