* Also, does this mean the max I can run the CPU is at 63Mhz with a divider `63_u8`? https://docs.rs/stm32h7xx-hal/latest/stm32h7xx\_hal/rtc/enum.RtcClock.html#variant.Lse

```
Hse
   Fields
     divider: u8
HSE (High-Speed External) divided by 2..=63

The resulting clock must be lower than 1MHz. This clock is automatically disabled by hardware when the CPU enters Stop or standby mode.
```