Want to discipline the RTC time with respect to UTC with the aid of UBLOX GPS module. what are the different ways I could do this?

[SM.31]

1. Use 1pps as external interrupt and count the number of pulses of RTC clock, then use sub second shift feature of RTC.

2. Supply the time pulse output of the UBLOX to the reference clock detection and configure the time pulse to be 60PPS and may be adjust duty cycle to 50 percent?

Im using a STM32H7 series Mcu- 5ppm RTC crystal 32.768khz , a Ublox neo M8 std modules.

Things I am looking for

Loss of GPS signal impact on time pulse signal and consequently on the RTC timing

RTC crystal ageing

For the reference clock detection I only found references to using it using mains supply

Pros and cons of each approach, any better approaches if any

Thanks

[SM.31]

@clive1 (NFA Crew) Can you please help me out?

[Tesla DeLorean]

Can't say I've dug into the H7 options here, but​

Should be able to export LSE via MCO pin(s)

Receiver has TIMEMARK input. Could measure pulse(s) from STM32 side.

Should be able to measure LSE with a TIM. Could measure 8x cycles against PLL.

Should be able to sample RTC via TIM/DMA trigger.

Could perhaps clock HSE from TP1/TP2.

Ethernet 1PPS input might be exploitable.​