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stm32/usb: assert usb clock is okay.

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This commit is contained in:
Dario Nieuwenhuis 2024-03-19 21:33:20 +01:00
parent daa64bd540
commit d90abb8ac9
1 changed files with 13 additions and 0 deletions
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13
embassy-stm32/src/usb/mod.rs
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@ -10,6 +10,19 @@ use crate::rcc::sealed::RccPeripheral;
/// clock, power initialization stuff that's common for USB and OTG. /// clock, power initialization stuff that's common for USB and OTG.
fn common_init<T: Instance>() { fn common_init<T: Instance>() {
// Check the USB clock is enabled and running at exactly 48 MHz.
// frequency() will panic if not enabled
let freq = T::frequency();
// Check frequency is within the 0.25% tolerance allowed by the spec.
// Clock might not be exact 48Mhz due to rounding errors in PLL calculation, or if the user
// has tight clock restrictions due to something else (like audio).
if freq.0.abs_diff(48_000_000) > 120_000 {
panic!(
"USB clock should be 48Mhz but is {} Hz. Please double-check your RCC settings.",
freq.0
)
}
#[cfg(any(stm32l4, stm32l5, stm32wb))] #[cfg(any(stm32l4, stm32l5, stm32wb))]
critical_section::with(|_| crate::pac::PWR.cr2().modify(|w| w.set_usv(true))); critical_section::with(|_| crate::pac::PWR.cr2().modify(|w| w.set_usv(true)));