RTC runs at 1/3 speed or sometimes does not intialise

[MedadRufus]

Swapping the crystal for the tracker running at 1/3 speed does not fix it. Could there be an error in setting the capacitors for this crystal?

[MedadRufus]

Could it be related to setting the drive level? https://st.force.com/community/s/question/0D50X0000BvkqIZSQY/inexplicably-slow-rtc

[MedadRufus]

Or leakage current due to flux? https://electronics.stackexchange.com/a/300414

[MedadRufus]

Could be related to setting the LSE drive level: ARMmbed/mbed-os#13797 (comment)

[MedadRufus]

The LSE crystal used for RTC is almost certainly the SC-20S by SII
https://www.sii.co.jp/en/quartz/files/2019/10/201909ST-test-Eng.pdf

[MedadRufus]

Some info on bad load capacitance

[MedadRufus]

More info on how the drive level could affect startup: ARMmbed/mbed-os#13781

[MedadRufus]

Consider backup like this:

        // Enable LSE Oscillator
        RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_LSE;
        RCC_OscInitStruct.PLL.PLLState   = RCC_PLL_NONE; /* Mandatory, otherwise the PLL is reconfigured! */
        RCC_OscInitStruct.LSEState       = RCC_LSE_ON; /* External 32.768 kHz clock on OSC_IN/OSC_OUT */
        if (HAL_RCC_OscConfig(&RCC_OscInitStruct) == HAL_OK) {
            // Connect LSE to RTC
            __HAL_RCC_RTC_CLKPRESCALER(RCC_RTCCLKSOURCE_LSE);
            __HAL_RCC_RTC_CONFIG(RCC_RTCCLKSOURCE_LSE);
            rtc_freq = LSE_VALUE;
        } else {
            // Enable LSI clock
            RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_LSI | RCC_OSCILLATORTYPE_LSE;
            RCC_OscInitStruct.PLL.PLLState   = RCC_PLL_NONE; // Mandatory, otherwise the PLL is reconfigured!
            RCC_OscInitStruct.LSEState       = RCC_LSE_OFF;
            RCC_OscInitStruct.LSIState       = RCC_LSI_ON;
            if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK) {
                error("RTC error: LSI clock initialization failed.");
            }
            // Connect LSI to RTC
            __HAL_RCC_RTC_CLKPRESCALER(RCC_RTCCLKSOURCE_LSI);
            __HAL_RCC_RTC_CONFIG(RCC_RTCCLKSOURCE_LSI);
            // [TODO] This value is LSI typical value. To be measured precisely using a timer input capture
            rtc_freq = LSI_VALUE;
        }

Source: https://os.mbed.com/questions/61064/How-to-enable-Nucleos-internal-lowspeed-/

[MedadRufus]

Looks like an issue specific to only one hardware instance. Not worth fixing. Just don't use this faulty tracker.