1 files changed, 27 insertions, 0 deletions

diff --git a/embassy-stm32/src/lib.rs b/embassy-stm32/src/lib.rs
index 6a3d1c463..05b1ff045 100644
--- a/embassy-stm32/src/lib.rs
+++ b/embassy-stm32/src/lib.rs
@@ -172,6 +172,14 @@ pub struct Config {
     #[cfg(dbgmcu)]
     pub enable_debug_during_sleep: bool,
 
+    /// On low-power boards (eg. `stm32l4`, `stm32l5` and `stm32u5`),
+    /// some GPIO pins are powered by an auxiliary, independent power supply (`VDDIO2`),
+    /// which needs to be enabled before these pins can be used.
+    ///
+    /// May increase power consumption. Defaults to true.
+    #[cfg(any(stm32l4, stm32l5, stm32u5))]
+    pub enable_independent_io_supply: bool,
+
     /// BDMA interrupt priority.
     ///
     /// Defaults to P0 (highest).
@@ -209,6 +217,8 @@ impl Default for Config {
             rcc: Default::default(),
             #[cfg(dbgmcu)]
             enable_debug_during_sleep: true,
+            #[cfg(any(stm32l4, stm32l5, stm32u5))]
+            enable_independent_io_supply: true,
             #[cfg(bdma)]
             bdma_interrupt_priority: Priority::P0,
             #[cfg(dma)]
@@ -270,6 +280,23 @@ pub fn init(config: Config) -> Peripherals {
         #[cfg(not(any(stm32f2, stm32f4, stm32f7, stm32l0, stm32h5, stm32h7)))]
         peripherals::FLASH::enable_and_reset_with_cs(cs);
 
+        // Enable the VDDIO2 power supply on chips that have it.
+        // Note that this requires the PWR peripheral to be enabled first.
+        #[cfg(any(stm32l4, stm32l5))]
+        {
+            crate::pac::PWR.cr2().modify(|w| {
+                // The official documentation states that we should ideally enable VDDIO2
+                // through the PVME2 bit, but it looks like this bit
+                w.set_iosv(config.enable_independent_io_supply);
+            });
+        }
+        #[cfg(stm32u5)]
+        {
+            crate::pac::PWR.svmcr().modify(|w| {
+                w.set_io2sv(config.enable_independent_io_supply);
+            });
+        }
+
         // dead battery functionality is still present on these
         // chips despite them not having UCPD- disable it
         #[cfg(any(stm32g070, stm32g0b0))]