Merge pull request #4729 from embassy-rs/mco2

stm32: add config to MCO to control the drive strength.

Author: Dirbaio

embassy-stm32/CHANGELOG.md

@@ -26,6 +26,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - fix: RTC register definition for STM32L4P5 and L4Q5 as they use v3 register map.
 - fix: Cut down the capabilities of the STM32L412 and L422 RTC as those are missing binary timer mode and underflow interrupt.
 - fix: Allow configuration of the internal pull up/down resistors on the pins for the Qei peripheral, as well as the Qei decoder mode.
+- feat: stm32/rcc/mco: Added support for IO driver strength when using Master Clock Out IO. This changes signature on Mco::new taking a McoConfig struct ([#4679](https://github.com/embassy-rs/embassy/pull/4679))
 
 ## 0.4.0 - 2025-08-26
 

embassy-stm32/src/rcc/mco.rs

@@ -91,12 +91,29 @@ pub struct Mco<'d, T: McoInstance> {
 
 impl<'d, T: McoInstance> Mco<'d, T> {
     /// Create a new MCO instance.
-    pub fn new(_peri: Peri<'d, T>, pin: Peri<'d, impl McoPin<T>>, source: T::Source, prescaler: McoPrescaler) -> Self {
+    pub fn new(_peri: Peri<'d, T>, pin: Peri<'d, impl McoPin<T>>, source: T::Source, config: McoConfig) -> Self {
         critical_section::with(|_| unsafe {
-            T::_apply_clock_settings(source, prescaler);
-            set_as_af!(pin, AfType::output(OutputType::PushPull, Speed::VeryHigh));
+            T::_apply_clock_settings(source, config.prescaler);
+            set_as_af!(pin, AfType::output(OutputType::PushPull, config.speed));
         });
 
         Self { phantom: PhantomData }
     }
 }
+
+#[non_exhaustive]
+pub struct McoConfig {
+    /// Master Clock Out prescaler
+    pub prescaler: McoPrescaler,
+    /// IO Drive Strength
+    pub speed: Speed,
+}
+
+impl Default for McoConfig {
+    fn default() -> Self {
+        Self {
+            prescaler: McoPrescaler::DIV1,
+            speed: Speed::VeryHigh,
+        }
+    }
+}

examples/stm32f4/src/bin/mco.rs

@@ -4,7 +4,7 @@
 use defmt::*;
 use embassy_executor::Spawner;
 use embassy_stm32::gpio::{Level, Output, Speed};
-use embassy_stm32::rcc::{Mco, Mco1Source, Mco2Source, McoPrescaler};
+use embassy_stm32::rcc::{Mco, Mco1Source, Mco2Source, McoConfig, McoPrescaler};
 use embassy_time::Timer;
 use {defmt_rtt as _, panic_probe as _};
 
@@ -13,8 +13,20 @@ async fn main(_spawner: Spawner) {
     let p = embassy_stm32::init(Default::default());
     info!("Hello World!");
 
-    let _mco1 = Mco::new(p.MCO1, p.PA8, Mco1Source::HSI, McoPrescaler::DIV1);
-    let _mco2 = Mco::new(p.MCO2, p.PC9, Mco2Source::PLL, McoPrescaler::DIV4);
+    let config_mco1 = {
+        let mut config = McoConfig::default();
+        config.prescaler = McoPrescaler::DIV1;
+        config
+    };
+
+    let config_mco2 = {
+        let mut config = McoConfig::default();
+        config.prescaler = McoPrescaler::DIV4;
+        config
+    };
+
+    let _mco1 = Mco::new(p.MCO1, p.PA8, Mco1Source::HSI, config_mco1);
+    let _mco2 = Mco::new(p.MCO2, p.PC9, Mco2Source::PLL, config_mco2);
     let mut led = Output::new(p.PB7, Level::High, Speed::Low);
 
     loop {

examples/stm32h5/src/bin/mco.rs

@@ -0,0 +1,29 @@
+#![no_std]
+#![no_main]
+
+use defmt::*;
+use embassy_executor::Spawner;
+use embassy_stm32::gpio::Speed;
+use embassy_stm32::rcc::{Mco, Mco2Source, McoConfig};
+use {defmt_rtt as _, panic_probe as _};
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    let p = embassy_stm32::init(Default::default());
+
+    /* Default "VeryHigh" drive strength and prescaler DIV1 */
+    // let _mco = Mco::new(p.MCO2, p.PC9, Mco2Source::SYS, McoConfig::default());
+
+    /* Choose Speed::Low drive strength */
+    let config = {
+        let mut config = McoConfig::default();
+        config.speed = Speed::Low;
+        config
+    };
+
+    let _mco = Mco::new(p.MCO2, p.PC9, Mco2Source::SYS, config);
+
+    info!("Clock out with low drive strength set on Master Clock Out 2 pin as AF on PC9");
+
+    loop {}
+}

examples/stm32h7/src/bin/camera.rs

@@ -5,7 +5,7 @@ use embassy_executor::Spawner;
 use embassy_stm32::dcmi::{self, *};
 use embassy_stm32::gpio::{Level, Output, Speed};
 use embassy_stm32::i2c::I2c;
-use embassy_stm32::rcc::{Mco, Mco1Source, McoPrescaler};
+use embassy_stm32::rcc::{Mco, Mco1Source, McoConfig, McoPrescaler};
 use embassy_stm32::{bind_interrupts, i2c, peripherals, Config};
 use embassy_time::Timer;
 use ov7725::*;
@@ -48,7 +48,14 @@ async fn main(_spawner: Spawner) {
     let p = embassy_stm32::init(config);
 
     defmt::info!("Hello World!");
-    let mco = Mco::new(p.MCO1, p.PA8, Mco1Source::HSI, McoPrescaler::DIV3);
+
+    let mco_config = {
+        let mut config = McoConfig::default();
+        config.prescaler = McoPrescaler::DIV3;
+        config
+    };
+
+    let mco = Mco::new(p.MCO1, p.PA8, Mco1Source::HSI, mco_config);
 
     let mut led = Output::new(p.PE3, Level::High, Speed::Low);
     let cam_i2c = I2c::new(p.I2C1, p.PB8, p.PB9, Irqs, p.DMA1_CH1, p.DMA1_CH2, Default::default());

examples/stm32h7/src/bin/mco.rs

@@ -4,7 +4,7 @@
 use defmt::*;
 use embassy_executor::Spawner;
 use embassy_stm32::gpio::{Level, Output, Speed};
-use embassy_stm32::rcc::{Mco, Mco1Source, McoPrescaler};
+use embassy_stm32::rcc::{Mco, Mco1Source, McoConfig, McoPrescaler};
 use embassy_time::Timer;
 use {defmt_rtt as _, panic_probe as _};
 
@@ -15,7 +15,13 @@ async fn main(_spawner: Spawner) {
 
     let mut led = Output::new(p.PB14, Level::High, Speed::Low);
 
-    let _mco = Mco::new(p.MCO1, p.PA8, Mco1Source::HSI, McoPrescaler::DIV8);
+    let config = {
+        let mut config = McoConfig::default();
+        config.prescaler = McoPrescaler::DIV8;
+        config
+    };
+
+    let _mco = Mco::new(p.MCO1, p.PA8, Mco1Source::HSI, config);
 
     loop {
         info!("high");

examples/stm32h7rs/src/bin/mco.rs

@@ -4,7 +4,7 @@
 use defmt::*;
 use embassy_executor::Spawner;
 use embassy_stm32::gpio::{Level, Output, Speed};
-use embassy_stm32::rcc::{Mco, Mco1Source, McoPrescaler};
+use embassy_stm32::rcc::{Mco, Mco1Source, McoConfig, McoPrescaler};
 use embassy_time::Timer;
 use {defmt_rtt as _, panic_probe as _};
 
@@ -15,7 +15,13 @@ async fn main(_spawner: Spawner) {
 
     let mut led = Output::new(p.PB14, Level::High, Speed::Low);
 
-    let _mco = Mco::new(p.MCO1, p.PA8, Mco1Source::HSI, McoPrescaler::DIV8);
+    let config = {
+        let mut config = McoConfig::default();
+        config.prescaler = McoPrescaler::DIV8;
+        config
+    };
+
+    let _mco = Mco::new(p.MCO1, p.PA8, Mco1Source::HSI, config);
 
     loop {
         info!("high");

examples/stm32l4/src/bin/mco.rs

@@ -4,7 +4,7 @@
 use defmt::*;
 use embassy_executor::Spawner;
 use embassy_stm32::gpio::{Level, Output, Speed};
-use embassy_stm32::rcc::{Mco, McoPrescaler, McoSource};
+use embassy_stm32::rcc::{Mco, McoConfig, McoPrescaler, McoSource};
 use embassy_time::Timer;
 use {defmt_rtt as _, panic_probe as _};
 
@@ -13,7 +13,13 @@ async fn main(_spawner: Spawner) {
     let p = embassy_stm32::init(Default::default());
     info!("Hello World!");
 
-    let _mco = Mco::new(p.MCO, p.PA8, McoSource::HSI, McoPrescaler::DIV1);
+    let config = {
+        let mut config = McoConfig::default();
+        config.prescaler = McoPrescaler::DIV1;
+        config
+    };
+
+    let _mco = Mco::new(p.MCO, p.PA8, McoSource::HSI, config);
 
     let mut led = Output::new(p.PB14, Level::High, Speed::Low);