What is the connection between RTCCLK and Sysclock?

[HCohe.1]

I am using hw_timerserver and sequencer for BLE. I added additional tasks to the sequencer for my application. It appeared that my tasks are running much too frequently, so I looked into the clock configuration of the RTC and found that WUCLK was driven by HSE and did not have the WU Clock and WU Counters configured properly. I switched the clock source to LSE, with WU clock & counters set to RTCCLK/16 & 2, for proper operation in Low-power modes. I then found that Systick was slowed down considerably. Any ideas?

[HCohe.1]

I attached the .ioc file. Can anyone explain why Systick is now slow as molasses after switching RTC to LSE? It was okay when HSE was used.

[Christophe Arnal]

Hello,

There is clearly no connection between RTCCLK and Systick.

I would check the configuration of the Systick. For an unknown reason, I believe it has been wrongly setup.

Regards.