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Use u32 instead of Duration for IWDG

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This commit is contained in:
chemicstry 2022-07-11 00:00:33 +03:00
parent 3bf1e1d4aa
commit d7d1e46a5f
2 changed files with 13 additions and 10 deletions
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21
embassy-stm32/src/wdg/mod.rs
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@ -1,6 +1,5 @@
use core::marker::PhantomData;
use embassy::time::Duration;
use embassy_hal_common::{unborrow, Unborrow};
use stm32_metapac::iwdg::vals::{Key, Pr};
@ -13,25 +12,29 @@ pub struct IndependentWatchdog<'d, T: Instance> {
// 12-bit counter
const MAX_RL: u16 = 0xFFF;
/// Calculates maximum watchdog timeout (RL = 0xFFF) for a given prescaler
const fn max_timeout(prescaler: u8) -> Duration {
Duration::from_micros(1_000_000 / (LSI_FREQ.0 / prescaler as u32) as u64 * MAX_RL as u64)
/// Calculates maximum watchdog timeout in us (RL = 0xFFF) for a given prescaler
const fn max_timeout(prescaler: u8) -> u32 {
1_000_000 * MAX_RL as u32 / (LSI_FREQ.0 / prescaler as u32)
}
/// Calculates watchdog reload value for the given prescaler and desired timeout
const fn reload_value(prescaler: u8, timeout: Duration) -> u16 {
((LSI_FREQ.0 / prescaler as u32) as u64 * timeout.as_micros() / 1_000_000) as u16
const fn reload_value(prescaler: u8, timeout_us: u32) -> u16 {
(timeout_us / prescaler as u32 * LSI_FREQ.0 / 1_000_000) as u16
}
impl<'d, T: Instance> IndependentWatchdog<'d, T> {
pub fn new(_instance: impl Unborrow<Target = T> + 'd, timeout: Duration) -> Self {
/// Creates an IWDG (Independent Watchdog) instance with a given timeout value in microseconds.
///
/// [Self] has to be started with [Self::unleash()].
/// Once timer expires, MCU will be reset. To prevent this, timer must be reloaded by repeatedly calling [Self::pet()] within timeout interval.
pub fn new(_instance: impl Unborrow<Target = T> + 'd, timeout_us: u32) -> Self {
unborrow!(_instance);
// Find lowest prescaler value, which makes watchdog period longer or equal to timeout.
// This iterates from 4 (2^2) to 256 (2^8).
let psc_power = unwrap!((2..=8).find(|psc_power| {
let psc = 2u8.pow(*psc_power);
timeout <= max_timeout(psc)
timeout_us <= max_timeout(psc)
}));
// Prescaler value
@ -42,7 +45,7 @@ impl<'d, T: Instance> IndependentWatchdog<'d, T> {
assert!(pr <= 0b110);
// Reload value
let rl = reload_value(psc, timeout);
let rl = reload_value(psc, timeout_us);
let wdg = T::regs();
unsafe {

2
examples/stm32f4/src/bin/wdt.rs
View File

@ -16,7 +16,7 @@ async fn main(_spawner: Spawner, p: Peripherals) {
let mut led = Output::new(p.PB7, Level::High, Speed::Low);
let mut wdt = IndependentWatchdog::new(p.IWDG, Duration::from_secs(1));
let mut wdt = IndependentWatchdog::new(p.IWDG, 1_000_000);
unsafe {
wdt.unleash();
}