panic if STM32 clock prescaler value overflows

Author: antonok-edm

rtic-monotonics/CHANGELOG.md

@@ -13,6 +13,7 @@ For each category, *Added*, *Changed*, *Fixed* add new entries at the top!
 
 - Updated esp32c3 dependency to v0.28.0
 - Updated esp32c3 dependency to v0.27.0
+- Panic if STM32 prescaler value would overflow
 
 ### Added
 

rtic-monotonics/src/stm32.rs

@@ -238,8 +238,8 @@ macro_rules! make_timer {
                 $timer.cr1().modify(|r| r.set_cen(false));
 
                 assert!((tim_clock_hz % timer_hz) == 0, "Unable to find suitable timer prescaler value!");
-                let psc = tim_clock_hz / timer_hz - 1;
-                $timer.psc().write(|r| r.set_psc(psc as u16));
+                let psc = u16::try_from(tim_clock_hz / timer_hz - 1).expect("Clock prescaler overflowed!");
+                $timer.psc().write(|r| r.set_psc(psc));
 
                 // Enable full-period interrupt.
                 $timer.dier().modify(|r| r.set_uie(true));