* Hi all, how important is this particular clock speed? See the 100Mhz setting in the blinky example below.  I'm wondering if this is causing some instability (see https://forum.arduino.cc/t/flashing-bin-file-for-blinky-demo-for-blue-led-gets-stuck-on-first-power-cycle/1218080)

```
#[entry]
fn main() -> ! {
    let cp = cortex_m::Peripherals::take().unwrap();
    let dp = pac::Peripherals::take().unwrap();

    // Constrain and Freeze power
    info!("Setup PWR...                  ");
    let pwr = dp.PWR.constrain();
    let mut pwrcfg = pwr.freeze();

    // Take the backup power domain
    let backup = pwrcfg.backup().unwrap();

    // Constrain and Freeze clock
    info!("Setup RCC...                  ");
    let rcc = dp.RCC.constrain();
    let ccdr = rcc.sys_ck(100.MHz()).freeze(pwrcfg, &dp.SYSCFG);

    info!("");
    info!("stm32h7xx-hal example - Blinky");
    info!("");

    let gpioe = dp.GPIOE.split(ccdr.peripheral.GPIOE);

    // Configure PE3     as output.
    let mut led = gpioe.pe3.into_push_pull_output();

    // Get the delay provider.
    let mut delay = cp.SYST.delay(ccdr.clocks);a

    loop {
        led.set_high();
        delay.delay_ms(1000_u16);

        led.set_low();
        delay.delay_ms(1000_u16);
    }
}
```