diff --git a/embassy-stm32/src/rcc/bd.rs b/embassy-stm32/src/rcc/bd.rs
index d774b993..762e8435 100644
--- a/embassy-stm32/src/rcc/bd.rs
+++ b/embassy-stm32/src/rcc/bd.rs
@@ -1,5 +1,5 @@
 #[allow(dead_code)]
-#[derive(Default)]
+#[derive(Default, Clone, Copy)]
 pub enum LseDrive {
     #[cfg(any(rtc_v2f7, rtc_v2l4))]
     Low = 0,
@@ -87,40 +87,42 @@ impl BackupDomain {
         rtc_v3u5
     ))]
     #[allow(dead_code, unused_variables)]
-    pub fn configure_ls(clock_source: RtcClockSource, lse_drive: Option<LseDrive>) {
-        match clock_source {
-            RtcClockSource::LSI => {
-                #[cfg(rtc_v3u5)]
-                let csr = crate::pac::RCC.bdcr();
+    pub fn configure_ls(clock_source: RtcClockSource, lsi: bool, lse: Option<LseDrive>) {
+        if lsi {
+            #[cfg(rtc_v3u5)]
+            let csr = crate::pac::RCC.bdcr();
 
-                #[cfg(not(rtc_v3u5))]
-                let csr = crate::pac::RCC.csr();
-
-                Self::modify(|_| {
-                    #[cfg(not(any(rcc_wb, rcc_wba)))]
-                    csr.modify(|w| w.set_lsion(true));
-
-                    #[cfg(any(rcc_wb, rcc_wba))]
-                    csr.modify(|w| w.set_lsi1on(true));
-                });
+            #[cfg(not(rtc_v3u5))]
+            let csr = crate::pac::RCC.csr();
 
+            Self::modify(|_| {
                 #[cfg(not(any(rcc_wb, rcc_wba)))]
-                while !csr.read().lsirdy() {}
+                csr.modify(|w| w.set_lsion(true));
 
                 #[cfg(any(rcc_wb, rcc_wba))]
-                while !csr.read().lsi1rdy() {}
-            }
-            RtcClockSource::LSE => {
-                let lse_drive = lse_drive.unwrap_or_default();
+                csr.modify(|w| w.set_lsi1on(true));
+            });
 
-                Self::modify(|w| {
-                    #[cfg(any(rtc_v2f7, rtc_v2h7, rtc_v2l0, rtc_v2l4))]
-                    w.set_lsedrv(lse_drive.into());
-                    w.set_lseon(true);
-                });
+            #[cfg(not(any(rcc_wb, rcc_wba)))]
+            while !csr.read().lsirdy() {}
 
-                while !Self::read().lserdy() {}
-            }
+            #[cfg(any(rcc_wb, rcc_wba))]
+            while !csr.read().lsi1rdy() {}
+        }
+
+        if let Some(lse_drive) = lse {
+            Self::modify(|w| {
+                #[cfg(any(rtc_v2f7, rtc_v2h7, rtc_v2l0, rtc_v2l4))]
+                w.set_lsedrv(lse_drive.into());
+                w.set_lseon(true);
+            });
+
+            while !Self::read().lserdy() {}
+        }
+
+        match clock_source {
+            RtcClockSource::LSI => assert!(lsi),
+            RtcClockSource::LSE => assert!(&lse.is_some()),
             _ => {}
         };
 
diff --git a/embassy-stm32/src/rcc/f2.rs b/embassy-stm32/src/rcc/f2.rs
index da88e44d..56ccdcbd 100644
--- a/embassy-stm32/src/rcc/f2.rs
+++ b/embassy-stm32/src/rcc/f2.rs
@@ -291,6 +291,8 @@ pub struct Config {
     pub pll: PLLConfig,
     pub mux: ClockSrc,
     pub rtc: Option<RtcClockSource>,
+    pub lsi: bool,
+    pub lse: Option<Hertz>,
     pub voltage: VoltageScale,
     pub ahb_pre: AHBPrescaler,
     pub apb1_pre: APBPrescaler,
@@ -308,6 +310,8 @@ impl Default for Config {
             voltage: VoltageScale::Scale3,
             mux: ClockSrc::HSI,
             rtc: None,
+            lsi: false,
+            lse: None,
             ahb_pre: AHBPrescaler::DIV1,
             apb1_pre: APBPrescaler::DIV1,
             apb2_pre: APBPrescaler::DIV1,
@@ -421,9 +425,11 @@ pub(crate) unsafe fn init(config: Config) {
     RCC.apb1enr().modify(|w| w.set_pwren(true));
     PWR.cr().read();
 
-    config
-        .rtc
-        .map(|clock_source| BackupDomain::configure_ls(clock_source, None));
+    BackupDomain::configure_ls(
+        config.rtc.unwrap_or(RtcClockSource::NOCLOCK),
+        config.lsi,
+        config.lse.map(|_| Default::default()),
+    );
 
     set_freqs(Clocks {
         sys: sys_clk,
diff --git a/embassy-stm32/src/rcc/f4.rs b/embassy-stm32/src/rcc/f4.rs
index f7bc0d99..d8d0312b 100644
--- a/embassy-stm32/src/rcc/f4.rs
+++ b/embassy-stm32/src/rcc/f4.rs
@@ -35,6 +35,8 @@ pub struct Config {
 
     pub pll48: bool,
     pub rtc: Option<RtcClockSource>,
+    pub lsi: bool,
+    pub lse: Option<Hertz>,
 }
 
 #[cfg(stm32f410)]
@@ -461,12 +463,15 @@ pub(crate) unsafe fn init(config: Config) {
         })
     });
 
-    config
-        .rtc
-        .map(|clock_source| BackupDomain::configure_ls(clock_source, None));
+    BackupDomain::configure_ls(
+        config.rtc.unwrap_or(RtcClockSource::NOCLOCK),
+        config.lsi,
+        config.lse.map(|_| Default::default()),
+    );
 
     let rtc = match config.rtc {
         Some(RtcClockSource::LSI) => Some(LSI_FREQ),
+        Some(RtcClockSource::LSE) => Some(config.lse.unwrap()),
         _ => None,
     };
 
diff --git a/embassy-stm32/src/rcc/l0.rs b/embassy-stm32/src/rcc/l0.rs
index 2dfd0232..1c655592 100644
--- a/embassy-stm32/src/rcc/l0.rs
+++ b/embassy-stm32/src/rcc/l0.rs
@@ -138,6 +138,8 @@ pub struct Config {
     #[cfg(crs)]
     pub enable_hsi48: bool,
     pub rtc: Option<RtcClockSource>,
+    pub lse: Option<Hertz>,
+    pub lsi: bool,
 }
 
 impl Default for Config {
@@ -151,6 +153,8 @@ impl Default for Config {
             #[cfg(crs)]
             enable_hsi48: false,
             rtc: None,
+            lse: None,
+            lsi: false,
         }
     }
 }
@@ -235,9 +239,11 @@ pub(crate) unsafe fn init(config: Config) {
         }
     };
 
-    config.rtc.map(|rtc| {
-        BackupDomain::configure_ls(rtc, None);
-    });
+    BackupDomain::configure_ls(
+        config.rtc.unwrap_or(RtcClockSource::NOCLOCK),
+        config.lsi,
+        config.lse.map(|_| Default::default()),
+    );
 
     RCC.cfgr().modify(|w| {
         w.set_sw(sw);
diff --git a/embassy-stm32/src/rcc/l4.rs b/embassy-stm32/src/rcc/l4.rs
index 447a57b2..f7b9354a 100644
--- a/embassy-stm32/src/rcc/l4.rs
+++ b/embassy-stm32/src/rcc/l4.rs
@@ -241,6 +241,8 @@ pub struct Config {
     #[cfg(not(any(stm32l471, stm32l475, stm32l476, stm32l486)))]
     pub hsi48: bool,
     pub rtc_mux: RtcClockSource,
+    pub lse: Option<Hertz>,
+    pub lsi: bool,
 }
 
 impl Default for Config {
@@ -255,6 +257,8 @@ impl Default for Config {
             #[cfg(not(any(stm32l471, stm32l475, stm32l476, stm32l486)))]
             hsi48: false,
             rtc_mux: RtcClockSource::LSI,
+            lsi: true,
+            lse: None,
         }
     }
 }
@@ -407,7 +411,7 @@ pub(crate) unsafe fn init(config: Config) {
 
     RCC.apb1enr1().modify(|w| w.set_pwren(true));
 
-    BackupDomain::configure_ls(config.rtc_mux, None);
+    BackupDomain::configure_ls(config.rtc_mux, config.lsi, config.lse.map(|_| Default::default()));
 
     let (sys_clk, sw) = match config.mux {
         ClockSrc::MSI(range) => {
diff --git a/embassy-stm32/src/rcc/mod.rs b/embassy-stm32/src/rcc/mod.rs
index 892dcf93..ff9b9bac 100644
--- a/embassy-stm32/src/rcc/mod.rs
+++ b/embassy-stm32/src/rcc/mod.rs
@@ -31,6 +31,16 @@ pub use _version::*;
 #[cfg(feature = "low-power")]
 use atomic_polyfill::{AtomicU32, Ordering};
 
+//  Model Clock Configuration
+//
+//  pub struct Clocks {
+//      hse: Option<Hertz>,
+//      hsi: bool,
+//      lse: Option<Hertz>,
+//      lsi: bool,
+//      rtc: RtcSource,
+//  }
+
 #[derive(Clone, Copy, Debug)]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub struct Clocks {
diff --git a/embassy-stm32/src/rcc/wb.rs b/embassy-stm32/src/rcc/wb.rs
index 3f4c3742..ee45a342 100644
--- a/embassy-stm32/src/rcc/wb.rs
+++ b/embassy-stm32/src/rcc/wb.rs
@@ -108,6 +108,7 @@ pub struct Pll {
 pub struct Config {
     pub hse: Option<Hse>,
     pub lse: Option<Hertz>,
+    pub lsi: bool,
     pub sys: Sysclk,
     pub mux: Option<PllMux>,
     pub pll48: Option<Pll48Source>,
@@ -136,6 +137,7 @@ pub const WPAN_DEFAULT: Config = Config {
     }),
     pll48: None,
     rtc: Some(RtcClockSource::LSE),
+    lsi: false,
 
     pll: Some(Pll {
         mul: 12,
@@ -164,6 +166,7 @@ impl Default for Config {
             pll: None,
             pllsai: None,
             rtc: None,
+            lsi: false,
 
             ahb1_pre: AHBPrescaler::DIV1,
             ahb2_pre: AHBPrescaler::DIV1,
@@ -294,9 +297,11 @@ pub(crate) fn configure_clocks(config: &Config) {
 
     rcc.cfgr().modify(|w| w.set_stopwuck(true));
 
-    config
-        .rtc
-        .map(|clock_source| BackupDomain::configure_ls(clock_source, None));
+    BackupDomain::configure_ls(
+        config.rtc.unwrap_or(RtcClockSource::NOCLOCK),
+        config.lsi,
+        config.lse.map(|_| Default::default()),
+    );
 
     match &config.hse {
         Some(hse) => {
diff --git a/embassy-stm32/src/rcc/wl.rs b/embassy-stm32/src/rcc/wl.rs
index 07856a28..5db942fc 100644
--- a/embassy-stm32/src/rcc/wl.rs
+++ b/embassy-stm32/src/rcc/wl.rs
@@ -138,6 +138,8 @@ pub struct Config {
     pub apb1_pre: APBPrescaler,
     pub apb2_pre: APBPrescaler,
     pub rtc_mux: RtcClockSource,
+    pub lse: Option<Hertz>,
+    pub lsi: bool,
     pub adc_clock_source: AdcClockSource,
 }
 
@@ -151,6 +153,8 @@ impl Default for Config {
             apb1_pre: APBPrescaler::DIV1,
             apb2_pre: APBPrescaler::DIV1,
             rtc_mux: RtcClockSource::LSI,
+            lsi: true,
+            lse: None,
             adc_clock_source: AdcClockSource::default(),
         }
     }
@@ -231,7 +235,7 @@ pub(crate) unsafe fn init(config: Config) {
     while FLASH.acr().read().latency() != ws {}
 
     // Enables the LSI if configured
-    BackupDomain::configure_ls(config.rtc_mux, None);
+    BackupDomain::configure_ls(config.rtc_mux, config.lsi, config.lse.map(|_| Default::default()));
 
     match config.mux {
         ClockSrc::HSI16 => {