Merge #1376

1376: rtc: cleanup and consolidate r=Dirbaio a=xoviat

This removes an extra file that I left in, adds an example, and consolidates the files into one 'v2' file.

Co-authored-by: xoviat <[email protected]>

20 files changed, 251 insertions, 534 deletions

diff --git a/embassy-stm32/src/lib.rs b/embassy-stm32/src/lib.rs
index 599041302..11820b7a0 100644
--- a/embassy-stm32/src/lib.rs
+++ b/embassy-stm32/src/lib.rs
@@ -51,7 +51,7 @@ pub mod pwm;
 pub mod qspi;
 #[cfg(rng)]
 pub mod rng;
-#[cfg(all(rtc, not(any(rtc_v1, rtc_v2f0, rtc_v2f7, rtc_v3, rtc_v3u5))))]
+#[cfg(all(rtc, not(rtc_v1)))]
 pub mod rtc;
 #[cfg(sdmmc)]
 pub mod sdmmc;
diff --git a/embassy-stm32/src/rtc/datetime.rs b/embassy-stm32/src/rtc/datetime.rs
index 6274c1e05..0a590c1bb 100644
--- a/embassy-stm32/src/rtc/datetime.rs
+++ b/embassy-stm32/src/rtc/datetime.rs
@@ -51,7 +51,7 @@ pub struct DateTime {
 impl From<chrono::NaiveDateTime> for DateTime {
     fn from(date_time: chrono::NaiveDateTime) -> Self {
         Self {
-            year: (date_time.year() - 1970) as u16,
+            year: date_time.year() as u16,
             month: date_time.month() as u8,
             day: date_time.day() as u8,
             day_of_week: date_time.weekday().into(),
@@ -65,14 +65,10 @@ impl From<chrono::NaiveDateTime> for DateTime {
 #[cfg(feature = "chrono")]
 impl From<DateTime> for chrono::NaiveDateTime {
     fn from(date_time: DateTime) -> Self {
-        NaiveDate::from_ymd_opt(
-            (date_time.year + 1970) as i32,
-            date_time.month as u32,
-            date_time.day as u32,
-        )
-        .unwrap()
-        .and_hms_opt(date_time.hour as u32, date_time.minute as u32, date_time.second as u32)
-        .unwrap()
+        NaiveDate::from_ymd_opt(date_time.year as i32, date_time.month as u32, date_time.day as u32)
+            .unwrap()
+            .and_hms_opt(date_time.hour as u32, date_time.minute as u32, date_time.second as u32)
+            .unwrap()
     }
 }
 
@@ -159,6 +155,8 @@ pub(super) fn write_date_time(rtc: &Rtc, t: DateTime) {
     let (yt, yu) = byte_to_bcd2(yr_offset);
 
     unsafe {
+        use crate::pac::rtc::vals::Ampm;
+
         rtc.tr().write(|w| {
             w.set_ht(ht);
             w.set_hu(hu);
@@ -166,7 +164,7 @@ pub(super) fn write_date_time(rtc: &Rtc, t: DateTime) {
             w.set_mnu(mnu);
             w.set_st(st);
             w.set_su(su);
-            w.set_pm(stm32_metapac::rtc::vals::Ampm::AM);
+            w.set_pm(Ampm::AM);
         });
 
         rtc.dr().write(|w| {
diff --git a/embassy-stm32/src/rtc/datetime_chrono.rs b/embassy-stm32/src/rtc/datetime_chrono.rs
deleted file mode 100644
index b46316cc9..000000000
--- a/embassy-stm32/src/rtc/datetime_chrono.rs
+++ /dev/null
@@ -1,85 +0,0 @@
-use chrono::{Datelike, Timelike};
-
-use super::byte_to_bcd2;
-use crate::pac::rtc::Rtc;
-
-/// Alias for [`chrono::NaiveDateTime`]
-pub type DateTime = chrono::NaiveDateTime;
-/// Alias for [`chrono::Weekday`]
-pub type DayOfWeek = chrono::Weekday;
-
-/// Errors regarding the [`DateTime`] and [`DateTimeFilter`] structs.
-///
-/// [`DateTimeFilter`]: struct.DateTimeFilter.html
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub enum Error {
-    /// The [DateTime] has an invalid year. The year must be between 0 and 4095.
-    InvalidYear,
-    /// The [DateTime] contains an invalid date.
-    InvalidDate,
-    /// The [DateTime] contains an invalid time.
-    InvalidTime,
-}
-
-pub(super) fn day_of_week_to_u8(dotw: DayOfWeek) -> u8 {
-    dotw.num_days_from_monday() as u8
-}
-
-pub(crate) fn validate_datetime(dt: &DateTime) -> Result<(), Error> {
-    if dt.year() < 0 || dt.year() > 4095 {
-        // rp2040 can't hold these years
-        Err(Error::InvalidYear)
-    } else {
-        // The rest of the chrono date is assumed to be valid
-        Ok(())
-    }
-}
-
-pub(super) fn write_date_time(rtc: &Rtc, t: DateTime) {
-    let (ht, hu) = byte_to_bcd2(t.hour() as u8);
-    let (mnt, mnu) = byte_to_bcd2(t.minute() as u8);
-    let (st, su) = byte_to_bcd2(t.second() as u8);
-
-    let (dt, du) = byte_to_bcd2(t.day() as u8);
-    let (mt, mu) = byte_to_bcd2(t.month() as u8);
-    let yr = t.year() as u16;
-    let yr_offset = (yr - 1970_u16) as u8;
-    let (yt, yu) = byte_to_bcd2(yr_offset);
-
-    unsafe {
-        rtc.tr().write(|w| {
-            w.set_ht(ht);
-            w.set_hu(hu);
-            w.set_mnt(mnt);
-            w.set_mnu(mnu);
-            w.set_st(st);
-            w.set_su(su);
-            w.set_pm(stm32_metapac::rtc::vals::Ampm::AM);
-        });
-
-        rtc.dr().write(|w| {
-            w.set_dt(dt);
-            w.set_du(du);
-            w.set_mt(mt > 0);
-            w.set_mu(mu);
-            w.set_yt(yt);
-            w.set_yu(yu);
-            w.set_wdu(day_of_week_to_u8(t.weekday()));
-        });
-    }
-}
-
-pub(super) fn datetime(
-    year: u16,
-    month: u8,
-    day: u8,
-    _day_of_week: u8,
-    hour: u8,
-    minute: u8,
-    second: u8,
-) -> Result<DateTime, Error> {
-    let date = chrono::NaiveDate::from_ymd_opt(year.into(), month.try_into().unwrap(), day.into())
-        .ok_or(Error::InvalidDate)?;
-    let time = chrono::NaiveTime::from_hms_opt(hour.into(), minute.into(), second.into()).ok_or(Error::InvalidTime)?;
-    Ok(DateTime::new(date, time))
-}
diff --git a/embassy-stm32/src/rtc/mod.rs b/embassy-stm32/src/rtc/mod.rs
index 170783b2d..962927fb1 100644
--- a/embassy-stm32/src/rtc/mod.rs
+++ b/embassy-stm32/src/rtc/mod.rs
@@ -10,12 +10,12 @@ pub use self::datetime::{DateTime, DayOfWeek, Error as DateTimeError};
     any(
         rtc_v2f0, rtc_v2f2, rtc_v2f3, rtc_v2f4, rtc_v2f7, rtc_v2h7, rtc_v2l0, rtc_v2l1, rtc_v2l4, rtc_v2wb
     ),
-    path = "v2/mod.rs"
+    path = "v2.rs"
 )]
 #[cfg_attr(any(rtc_v3, rtc_v3u5), path = "v3.rs")]
-mod versions;
+mod _version;
+pub use _version::*;
 use embassy_hal_common::Peripheral;
-pub use versions::*;
 
 /// Errors that can occur on methods on [RtcClock]
 #[derive(Clone, Debug, PartialEq, Eq)]
@@ -113,7 +113,7 @@ impl Default for RtcCalibrationCyclePeriod {
 
 impl<'d, T: Instance> Rtc<'d, T> {
     pub fn new(_rtc: impl Peripheral<P = T> + 'd, rtc_config: RtcConfig) -> Self {
-        unsafe { enable_peripheral_clk() };
+        unsafe { T::enable_peripheral_clk() };
 
         let mut rtc_struct = Self {
             phantom: PhantomData,
@@ -179,14 +179,14 @@ impl<'d, T: Instance> Rtc<'d, T> {
         self.rtc_config
     }
 
-    pub const BACKUP_REGISTER_COUNT: usize = BACKUP_REGISTER_COUNT;
+    pub const BACKUP_REGISTER_COUNT: usize = T::BACKUP_REGISTER_COUNT;
 
     /// Read content of the backup register.
     ///
     /// The registers retain their values during wakes from standby mode or system resets. They also
     /// retain their value when Vdd is switched off as long as V_BAT is powered.
     pub fn read_backup_register(&self, register: usize) -> Option<u32> {
-        read_backup_register(&T::regs(), register)
+        T::read_backup_register(&T::regs(), register)
     }
 
     /// Set content of the backup register.
@@ -194,7 +194,7 @@ impl<'d, T: Instance> Rtc<'d, T> {
     /// The registers retain their values during wakes from standby mode or system resets. They also
     /// retain their value when Vdd is switched off as long as V_BAT is powered.
     pub fn write_backup_register(&self, register: usize, value: u32) {
-        write_backup_register(&T::regs(), register, value)
+        T::write_backup_register(&T::regs(), register, value)
     }
 }
 
@@ -219,17 +219,31 @@ pub(crate) fn bcd2_to_byte(bcd: (u8, u8)) -> u8 {
 }
 
 pub(crate) mod sealed {
+    use crate::pac::rtc::Rtc;
+
     pub trait Instance {
-        fn regs() -> crate::pac::rtc::Rtc;
-    }
-}
+        const BACKUP_REGISTER_COUNT: usize;
 
-pub trait Instance: sealed::Instance + 'static {}
+        fn regs() -> Rtc {
+            crate::pac::RTC
+        }
 
-impl sealed::Instance for crate::peripherals::RTC {
-    fn regs() -> crate::pac::rtc::Rtc {
-        crate::pac::RTC
+        unsafe fn enable_peripheral_clk() {}
+
+        /// Read content of the backup register.
+        ///
+        /// The registers retain their values during wakes from standby mode or system resets. They also
+        /// retain their value when Vdd is switched off as long as V_BAT is powered.
+        fn read_backup_register(rtc: &Rtc, register: usize) -> Option<u32>;
+
+        /// Set content of the backup register.
+        ///
+        /// The registers retain their values during wakes from standby mode or system resets. They also
+        /// retain their value when Vdd is switched off as long as V_BAT is powered.
+        fn write_backup_register(rtc: &Rtc, register: usize, value: u32);
+
+        // fn apply_config(&mut self, rtc_config: RtcConfig);
     }
 }
 
-impl Instance for crate::peripherals::RTC {}
+pub trait Instance: sealed::Instance + 'static {}
diff --git a/embassy-stm32/src/rtc/v2/mod.rs b/embassy-stm32/src/rtc/v2.rs
index 296adae89..adaafe67a 100644
--- a/embassy-stm32/src/rtc/v2/mod.rs
+++ b/embassy-stm32/src/rtc/v2.rs
@@ -1,29 +1,78 @@
 use stm32_metapac::rtc::vals::{Init, Osel, Pol};
 
-use super::{Instance, RtcConfig};
+use super::{sealed, Instance, RtcConfig};
 use crate::pac::rtc::Rtc;
 
-#[cfg_attr(rtc_v2f0, path = "v2f0.rs")]
-#[cfg_attr(rtc_v2f2, path = "v2f2.rs")]
-#[cfg_attr(rtc_v2f3, path = "v2f3.rs")]
-#[cfg_attr(rtc_v2f4, path = "v2f4.rs")]
-#[cfg_attr(rtc_v2f7, path = "v2f7.rs")]
-#[cfg_attr(rtc_v2h7, path = "v2h7.rs")]
-#[cfg_attr(rtc_v2l0, path = "v2l0.rs")]
-#[cfg_attr(rtc_v2l1, path = "v2l1.rs")]
-#[cfg_attr(rtc_v2l4, path = "v2l4.rs")]
-#[cfg_attr(rtc_v2wb, path = "v2wb.rs")]
-mod family;
-
-pub use family::*;
-
 impl<'d, T: Instance> super::Rtc<'d, T> {
     /// Applies the RTC config
     /// It this changes the RTC clock source the time will be reset
     pub(super) fn apply_config(&mut self, rtc_config: RtcConfig) {
         // Unlock the backup domain
         unsafe {
-            unlock_backup_domain(rtc_config.clock_config as u8);
+            let clock_config = rtc_config.clock_config as u8;
+
+            #[cfg(not(rtc_v2wb))]
+            use stm32_metapac::rcc::vals::Rtcsel;
+
+            #[cfg(any(rtc_v2f2, rtc_v2f3, rtc_v2l1))]
+            let cr = crate::pac::PWR.cr();
+            #[cfg(any(rtc_v2f4, rtc_v2f7, rtc_v2h7, rtc_v2l4, rtc_v2wb))]
+            let cr = crate::pac::PWR.cr1();
+
+            // TODO: Missing from PAC for l0 and f0?
+            #[cfg(not(any(rtc_v2f0, rtc_v2l0)))]
+            {
+                cr.modify(|w| w.set_dbp(true));
+                while !cr.read().dbp() {}
+            }
+
+            #[cfg(not(any(rtc_v2l0, rtc_v2l1)))]
+            let reg = crate::pac::RCC.bdcr().read();
+            #[cfg(any(rtc_v2l0, rtc_v2l1))]
+            let reg = crate::pac::RCC.csr().read();
+
+            #[cfg(any(rtc_v2h7, rtc_v2l4, rtc_v2wb))]
+            assert!(!reg.lsecsson(), "RTC is not compatible with LSE CSS, yet.");
+
+            #[cfg(rtc_v2wb)]
+            let rtcsel = reg.rtcsel();
+            #[cfg(not(rtc_v2wb))]
+            let rtcsel = reg.rtcsel().0;
+
+            if !reg.rtcen() || rtcsel != clock_config {
+                #[cfg(not(any(rtc_v2l0, rtc_v2l1)))]
+                crate::pac::RCC.bdcr().modify(|w| w.set_bdrst(true));
+
+                #[cfg(not(any(rtc_v2l0, rtc_v2l1)))]
+                let cr = crate::pac::RCC.bdcr();
+                #[cfg(any(rtc_v2l0, rtc_v2l1))]
+                let cr = crate::pac::RCC.csr();
+
+                cr.modify(|w| {
+                    // Reset
+                    #[cfg(not(any(rtc_v2l0, rtc_v2l1)))]
+                    w.set_bdrst(false);
+
+                    // Select RTC source
+                    #[cfg(not(rtc_v2wb))]
+                    w.set_rtcsel(Rtcsel(clock_config));
+                    #[cfg(rtc_v2wb)]
+                    w.set_rtcsel(clock_config);
+                    w.set_rtcen(true);
+
+                    // Restore bcdr
+                    #[cfg(any(rtc_v2l4, rtc_v2wb))]
+                    w.set_lscosel(reg.lscosel());
+                    #[cfg(any(rtc_v2l4, rtc_v2wb))]
+                    w.set_lscoen(reg.lscoen());
+
+                    w.set_lseon(reg.lseon());
+
+                    #[cfg(any(rtc_v2f0, rtc_v2f7, rtc_v2h7, rtc_v2l4, rtc_v2wb))]
+                    w.set_lsedrv(reg.lsedrv());
+                    w.set_lsebyp(reg.lsebyp());
+                });
+            }
         }
 
         self.write(true, |rtc| unsafe {
@@ -148,24 +197,33 @@ impl<'d, T: Instance> super::Rtc<'d, T> {
     }
 }
 
-/// Read content of the backup register.
-///
-/// The registers retain their values during wakes from standby mode or system resets. They also
-/// retain their value when Vdd is switched off as long as V_BAT is powered.
-pub fn read_backup_register(rtc: &Rtc, register: usize) -> Option<u32> {
-    if register < BACKUP_REGISTER_COUNT {
-        Some(unsafe { rtc.bkpr(register).read().bkp() })
-    } else {
-        None
+impl sealed::Instance for crate::peripherals::RTC {
+    const BACKUP_REGISTER_COUNT: usize = 20;
+
+    unsafe fn enable_peripheral_clk() {
+        #[cfg(any(rtc_v2l4, rtc_v2wb))]
+        {
+            // enable peripheral clock for communication
+            crate::pac::RCC.apb1enr1().modify(|w| w.set_rtcapben(true));
+
+            // read to allow the pwr clock to enable
+            crate::pac::PWR.cr1().read();
+        }
     }
-}
 
-/// Set content of the backup register.
-///
-/// The registers retain their values during wakes from standby mode or system resets. They also
-/// retain their value when Vdd is switched off as long as V_BAT is powered.
-pub fn write_backup_register(rtc: &Rtc, register: usize, value: u32) {
-    if register < BACKUP_REGISTER_COUNT {
-        unsafe { rtc.bkpr(register).write(|w| w.set_bkp(value)) }
+    fn read_backup_register(rtc: &Rtc, register: usize) -> Option<u32> {
+        if register < Self::BACKUP_REGISTER_COUNT {
+            Some(unsafe { rtc.bkpr(register).read().bkp() })
+        } else {
+            None
+        }
+    }
+
+    fn write_backup_register(rtc: &Rtc, register: usize, value: u32) {
+        if register < Self::BACKUP_REGISTER_COUNT {
+            unsafe { rtc.bkpr(register).write(|w| w.set_bkp(value)) }
+        }
     }
 }
+
+impl Instance for crate::peripherals::RTC {}
diff --git a/embassy-stm32/src/rtc/v2/v2f0.rs b/embassy-stm32/src/rtc/v2/v2f0.rs
deleted file mode 100644
index d6871d91e..000000000
--- a/embassy-stm32/src/rtc/v2/v2f0.rs
+++ /dev/null
@@ -1,41 +0,0 @@
-use stm32_metapac::rcc::vals::Rtcsel;
-
-pub const BACKUP_REGISTER_COUNT: usize = 20;
-
-/// Unlock the backup domain
-pub(super) unsafe fn unlock_backup_domain(clock_config: u8) {
-    crate::pac::PWR.cr1().modify(|w| w.set_dbp(true));
-    while !crate::pac::PWR.cr1().read().dbp() {}
-
-    let reg = crate::pac::RCC.bdcr().read();
-    assert!(!reg.lsecsson(), "RTC is not compatible with LSE CSS, yet.");
-
-    if !reg.rtcen() || reg.rtcsel().0 != clock_config {
-        crate::pac::RCC.bdcr().modify(|w| w.set_bdrst(true));
-
-        crate::pac::RCC.bdcr().modify(|w| {
-            // Reset
-            w.set_bdrst(false);
-
-            // Select RTC source
-            w.set_rtcsel(Rtcsel(clock_config));
-            w.set_rtcen(true);
-
-            // Restore bcdr
-            w.set_lscosel(reg.lscosel());
-            w.set_lscoen(reg.lscoen());
-
-            w.set_lseon(reg.lseon());
-            w.set_lsedrv(reg.lsedrv());
-            w.set_lsebyp(reg.lsebyp());
-        });
-    }
-}
-
-pub(crate) unsafe fn enable_peripheral_clk() {
-    // enable peripheral clock for communication
-    crate::pac::RCC.apb1enr1().modify(|w| w.set_rtcapben(true));
-
-    // read to allow the pwr clock to enable
-    crate::pac::PWR.cr1().read();
-}
diff --git a/embassy-stm32/src/rtc/v2/v2f2.rs b/embassy-stm32/src/rtc/v2/v2f2.rs
deleted file mode 100644
index e041f3f4e..000000000
--- a/embassy-stm32/src/rtc/v2/v2f2.rs
+++ /dev/null
@@ -1,31 +0,0 @@
-use stm32_metapac::rcc::vals::Rtcsel;
-
-pub const BACKUP_REGISTER_COUNT: usize = 20;
-
-/// Unlock the backup domain
-pub(super) unsafe fn unlock_backup_domain(clock_config: u8) {
-    crate::pac::PWR.cr().modify(|w| w.set_dbp(true));
-    while !crate::pac::PWR.cr().read().dbp() {}
-
-    let reg = crate::pac::RCC.bdcr().read();
-
-    if !reg.rtcen() || reg.rtcsel().0 != clock_config {
-        crate::pac::RCC.bdcr().modify(|w| w.set_bdrst(true));
-
-        crate::pac::RCC.bdcr().modify(|w| {
-            // Reset
-            w.set_bdrst(false);
-
-            // Select RTC source
-            w.set_rtcsel(Rtcsel(clock_config));
-            w.set_rtcen(true);
-
-            w.set_lseon(reg.lseon());
-            w.set_lsebyp(reg.lsebyp());
-        });
-    }
-}
-
-pub(crate) unsafe fn enable_peripheral_clk() {
-    // Nothing to do
-}
diff --git a/embassy-stm32/src/rtc/v2/v2f3.rs b/embassy-stm32/src/rtc/v2/v2f3.rs
deleted file mode 100644
index e041f3f4e..000000000
--- a/embassy-stm32/src/rtc/v2/v2f3.rs
+++ /dev/null
@@ -1,31 +0,0 @@
-use stm32_metapac::rcc::vals::Rtcsel;
-
-pub const BACKUP_REGISTER_COUNT: usize = 20;
-
-/// Unlock the backup domain
-pub(super) unsafe fn unlock_backup_domain(clock_config: u8) {
-    crate::pac::PWR.cr().modify(|w| w.set_dbp(true));
-    while !crate::pac::PWR.cr().read().dbp() {}
-
-    let reg = crate::pac::RCC.bdcr().read();
-
-    if !reg.rtcen() || reg.rtcsel().0 != clock_config {
-        crate::pac::RCC.bdcr().modify(|w| w.set_bdrst(true));
-
-        crate::pac::RCC.bdcr().modify(|w| {
-            // Reset
-            w.set_bdrst(false);
-
-            // Select RTC source
-            w.set_rtcsel(Rtcsel(clock_config));
-            w.set_rtcen(true);
-
-            w.set_lseon(reg.lseon());
-            w.set_lsebyp(reg.lsebyp());
-        });
-    }
-}
-
-pub(crate) unsafe fn enable_peripheral_clk() {
-    // Nothing to do
-}
diff --git a/embassy-stm32/src/rtc/v2/v2f4.rs b/embassy-stm32/src/rtc/v2/v2f4.rs
deleted file mode 100644
index 4dd21cae4..000000000
--- a/embassy-stm32/src/rtc/v2/v2f4.rs
+++ /dev/null
@@ -1,31 +0,0 @@
-use stm32_metapac::rcc::vals::Rtcsel;
-
-pub const BACKUP_REGISTER_COUNT: usize = 20;
-
-/// Unlock the backup domain
-pub(super) unsafe fn unlock_backup_domain(clock_config: u8) {
-    crate::pac::PWR.cr1().modify(|w| w.set_dbp(true));
-    while !crate::pac::PWR.cr1().read().dbp() {}
-
-    let reg = crate::pac::RCC.bdcr().read();
-
-    if !reg.rtcen() || reg.rtcsel().0 != clock_config {
-        crate::pac::RCC.bdcr().modify(|w| w.set_bdrst(true));
-
-        crate::pac::RCC.bdcr().modify(|w| {
-            // Reset
-            w.set_bdrst(false);
-
-            // Select RTC source
-            w.set_rtcsel(Rtcsel(clock_config));
-            w.set_rtcen(true);
-
-            w.set_lseon(reg.lseon());
-            w.set_lsebyp(reg.lsebyp());
-        });
-    }
-}
-
-pub(crate) unsafe fn enable_peripheral_clk() {
-    // Nothing to do
-}
diff --git a/embassy-stm32/src/rtc/v2/v2f7.rs b/embassy-stm32/src/rtc/v2/v2f7.rs
deleted file mode 100644
index d6871d91e..000000000
--- a/embassy-stm32/src/rtc/v2/v2f7.rs
+++ /dev/null
@@ -1,41 +0,0 @@
-use stm32_metapac::rcc::vals::Rtcsel;
-
-pub const BACKUP_REGISTER_COUNT: usize = 20;
-
-/// Unlock the backup domain
-pub(super) unsafe fn unlock_backup_domain(clock_config: u8) {
-    crate::pac::PWR.cr1().modify(|w| w.set_dbp(true));
-    while !crate::pac::PWR.cr1().read().dbp() {}
-
-    let reg = crate::pac::RCC.bdcr().read();
-    assert!(!reg.lsecsson(), "RTC is not compatible with LSE CSS, yet.");
-
-    if !reg.rtcen() || reg.rtcsel().0 != clock_config {
-        crate::pac::RCC.bdcr().modify(|w| w.set_bdrst(true));
-
-        crate::pac::RCC.bdcr().modify(|w| {
-            // Reset
-            w.set_bdrst(false);
-
-            // Select RTC source
-            w.set_rtcsel(Rtcsel(clock_config));
-            w.set_rtcen(true);
-
-            // Restore bcdr
-            w.set_lscosel(reg.lscosel());
-            w.set_lscoen(reg.lscoen());
-
-            w.set_lseon(reg.lseon());
-            w.set_lsedrv(reg.lsedrv());
-            w.set_lsebyp(reg.lsebyp());
-        });
-    }
-}
-
-pub(crate) unsafe fn enable_peripheral_clk() {
-    // enable peripheral clock for communication
-    crate::pac::RCC.apb1enr1().modify(|w| w.set_rtcapben(true));
-
-    // read to allow the pwr clock to enable
-    crate::pac::PWR.cr1().read();
-}
diff --git a/embassy-stm32/src/rtc/v2/v2h7.rs b/embassy-stm32/src/rtc/v2/v2h7.rs
deleted file mode 100644
index f3b180683..000000000
--- a/embassy-stm32/src/rtc/v2/v2h7.rs
+++ /dev/null
@@ -1,33 +0,0 @@
-use stm32_metapac::rcc::vals::Rtcsel;
-
-pub const BACKUP_REGISTER_COUNT: usize = 20;
-
-/// Unlock the backup domain
-pub(super) unsafe fn unlock_backup_domain(clock_config: u8) {
-    crate::pac::PWR.cr1().modify(|w| w.set_dbp(true));
-    while !crate::pac::PWR.cr1().read().dbp() {}
-
-    let reg = crate::pac::RCC.bdcr().read();
-    assert!(!reg.lsecsson(), "RTC is not compatible with LSE CSS, yet.");
-
-    if !reg.rtcen() || reg.rtcsel().0 != clock_config {
-        crate::pac::RCC.bdcr().modify(|w| w.set_bdrst(true));
-
-        crate::pac::RCC.bdcr().modify(|w| {
-            // Reset
-            w.set_bdrst(false);
-
-            // Select RTC source
-            w.set_rtcsel(Rtcsel(clock_config));
-            w.set_rtcen(true);
-
-            w.set_lseon(reg.lseon());
-            w.set_lsedrv(reg.lsedrv());
-            w.set_lsebyp(reg.lsebyp());
-        });
-    }
-}
-
-pub(crate) unsafe fn enable_peripheral_clk() {
-    // Nothing to do
-}
diff --git a/embassy-stm32/src/rtc/v2/v2l0.rs b/embassy-stm32/src/rtc/v2/v2l0.rs
deleted file mode 100644
index dbd3b0882..000000000
--- a/embassy-stm32/src/rtc/v2/v2l0.rs
+++ /dev/null
@@ -1,26 +0,0 @@
-pub const BACKUP_REGISTER_COUNT: usize = 20;
-
-/// Unlock the backup domain
-pub(super) unsafe fn unlock_backup_domain(clock_config: u8) {
-    // TODO: Missing from PAC?
-    // crate::pac::PWR.cr().modify(|w| w.set_dbp(true));
-    // while !crate::pac::PWR.cr().read().dbp() {}
-
-    let reg = crate::pac::RCC.csr().read();
-
-    if !reg.rtcen() || reg.rtcsel().0 != clock_config {
-        crate::pac::RCC.csr().modify(|w| {
-            // Select RTC source
-            w.set_rtcsel(crate::pac::rcc::vals::Rtcsel(clock_config));
-            w.set_rtcen(true);
-
-            w.set_lseon(reg.lseon());
-            w.set_lsedrv(reg.lsedrv());
-            w.set_lsebyp(reg.lsebyp());
-        });
-    }
-}
-
-pub(crate) unsafe fn enable_peripheral_clk() {
-    // Nothing to do
-}
diff --git a/embassy-stm32/src/rtc/v2/v2l1.rs b/embassy-stm32/src/rtc/v2/v2l1.rs
deleted file mode 100644
index 1ac78b31a..000000000
--- a/embassy-stm32/src/rtc/v2/v2l1.rs
+++ /dev/null
@@ -1,24 +0,0 @@
-pub const BACKUP_REGISTER_COUNT: usize = 20;
-
-/// Unlock the backup domain
-pub(super) unsafe fn unlock_backup_domain(clock_config: u8) {
-    crate::pac::PWR.cr().modify(|w| w.set_dbp(true));
-    while !crate::pac::PWR.cr().read().dbp() {}
-
-    let reg = crate::pac::RCC.csr().read();
-
-    if !reg.rtcen() || reg.rtcsel().0 != clock_config {
-        crate::pac::RCC.csr().modify(|w| {
-            // Select RTC source
-            w.set_rtcsel(crate::pac::rcc::vals::Rtcsel(clock_config));
-            w.set_rtcen(true);
-
-            w.set_lseon(reg.lseon());
-            w.set_lsebyp(reg.lsebyp());
-        });
-    }
-}
-
-pub(crate) unsafe fn enable_peripheral_clk() {
-    // Nothing to do
-}
diff --git a/embassy-stm32/src/rtc/v2/v2l4.rs b/embassy-stm32/src/rtc/v2/v2l4.rs
deleted file mode 100644
index d6871d91e..000000000
--- a/embassy-stm32/src/rtc/v2/v2l4.rs
+++ /dev/null
@@ -1,41 +0,0 @@
-use stm32_metapac::rcc::vals::Rtcsel;
-
-pub const BACKUP_REGISTER_COUNT: usize = 20;
-
-/// Unlock the backup domain
-pub(super) unsafe fn unlock_backup_domain(clock_config: u8) {
-    crate::pac::PWR.cr1().modify(|w| w.set_dbp(true));
-    while !crate::pac::PWR.cr1().read().dbp() {}
-
-    let reg = crate::pac::RCC.bdcr().read();
-    assert!(!reg.lsecsson(), "RTC is not compatible with LSE CSS, yet.");
-
-    if !reg.rtcen() || reg.rtcsel().0 != clock_config {
-        crate::pac::RCC.bdcr().modify(|w| w.set_bdrst(true));
-
-        crate::pac::RCC.bdcr().modify(|w| {
-            // Reset
-            w.set_bdrst(false);
-
-            // Select RTC source
-            w.set_rtcsel(Rtcsel(clock_config));
-            w.set_rtcen(true);
-
-            // Restore bcdr
-            w.set_lscosel(reg.lscosel());
-            w.set_lscoen(reg.lscoen());
-
-            w.set_lseon(reg.lseon());
-            w.set_lsedrv(reg.lsedrv());
-            w.set_lsebyp(reg.lsebyp());
-        });
-    }
-}
-
-pub(crate) unsafe fn enable_peripheral_clk() {
-    // enable peripheral clock for communication
-    crate::pac::RCC.apb1enr1().modify(|w| w.set_rtcapben(true));
-
-    // read to allow the pwr clock to enable
-    crate::pac::PWR.cr1().read();
-}
diff --git a/embassy-stm32/src/rtc/v2/v2wb.rs b/embassy-stm32/src/rtc/v2/v2wb.rs
deleted file mode 100644
index 98761fa60..000000000
--- a/embassy-stm32/src/rtc/v2/v2wb.rs
+++ /dev/null
@@ -1,39 +0,0 @@
-pub const BACKUP_REGISTER_COUNT: usize = 20;
-
-/// Unlock the backup domain
-pub(super) unsafe fn unlock_backup_domain(clock_config: u8) {
-    crate::pac::PWR.cr1().modify(|w| w.set_dbp(true));
-    while !crate::pac::PWR.cr1().read().dbp() {}
-
-    let reg = crate::pac::RCC.bdcr().read();
-    assert!(!reg.lsecsson(), "RTC is not compatible with LSE CSS, yet.");
-
-    if !reg.rtcen() || reg.rtcsel() != clock_config {
-        crate::pac::RCC.bdcr().modify(|w| w.set_bdrst(true));
-
-        crate::pac::RCC.bdcr().modify(|w| {
-            // Reset
-            w.set_bdrst(false);
-
-            // Select RTC source
-            w.set_rtcsel(clock_config);
-            w.set_rtcen(true);
-
-            // Restore bcdr
-            w.set_lscosel(reg.lscosel());
-            w.set_lscoen(reg.lscoen());
-
-            w.set_lseon(reg.lseon());
-            w.set_lsedrv(reg.lsedrv());
-            w.set_lsebyp(reg.lsebyp());
-        });
-    }
-}
-
-pub(crate) unsafe fn enable_peripheral_clk() {
-    // enable peripheral clock for communication
-    crate::pac::RCC.apb1enr1().modify(|w| w.set_rtcapben(true));
-
-    // read to allow the pwr clock to enable
-    crate::pac::PWR.cr1().read();
-}
diff --git a/embassy-stm32/src/rtc/v3.rs b/embassy-stm32/src/rtc/v3.rs
index 6998c48c2..19c52ee02 100644
--- a/embassy-stm32/src/rtc/v3.rs
+++ b/embassy-stm32/src/rtc/v3.rs
@@ -1,6 +1,6 @@
 use stm32_metapac::rtc::vals::{Calp, Calw16, Calw8, Fmt, Init, Key, Osel, Pol, TampalrmPu, TampalrmType};
 
-use super::{Instance, RtcCalibrationCyclePeriod, RtcConfig};
+use super::{sealed, Instance, RtcCalibrationCyclePeriod, RtcConfig};
 use crate::pac::rtc::Rtc;
 
 impl<'d, T: Instance> super::Rtc<'d, T> {
@@ -9,43 +9,30 @@ impl<'d, T: Instance> super::Rtc<'d, T> {
     pub(super) fn apply_config(&mut self, rtc_config: RtcConfig) {
         // Unlock the backup domain
         unsafe {
-            #[cfg(feature = "stm32g0c1ve")]
+            #[cfg(any(rtc_v3u5, rcc_g0))]
+            use crate::pac::rcc::vals::Rtcsel;
+            #[cfg(not(any(rtc_v3u5, rcc_g0, rcc_g4, rcc_wl5, rcc_wle)))]
+            use crate::pac::rtc::vals::Rtcsel;
+
+            #[cfg(not(any(rtc_v3u5, rcc_wl5, rcc_wle)))]
             {
                 crate::pac::PWR.cr1().modify(|w| w.set_dbp(true));
                 while !crate::pac::PWR.cr1().read().dbp() {}
             }
-
-            #[cfg(not(any(
-                feature = "stm32g0c1ve",
-                feature = "stm32g491re",
-                feature = "stm32u585zi",
-                feature = "stm32g473cc"
-            )))]
+            #[cfg(any(rcc_wl5, rcc_wle))]
             {
-                crate::pac::PWR
-                    .cr1()
-                    .modify(|w| w.set_dbp(stm32_metapac::pwr::vals::Dbp::ENABLED));
-                while crate::pac::PWR.cr1().read().dbp() != stm32_metapac::pwr::vals::Dbp::DISABLED {}
+                use crate::pac::pwr::vals::Dbp;
+
+                crate::pac::PWR.cr1().modify(|w| w.set_dbp(Dbp::ENABLED));
+                while crate::pac::PWR.cr1().read().dbp() != Dbp::ENABLED {}
             }
 
             let reg = crate::pac::RCC.bdcr().read();
             assert!(!reg.lsecsson(), "RTC is not compatible with LSE CSS, yet.");
 
             let config_rtcsel = rtc_config.clock_config as u8;
-            #[cfg(not(any(
-                feature = "stm32wl54jc-cm0p",
-                feature = "stm32wle5ub",
-                feature = "stm32g0c1ve",
-                feature = "stm32wl55jc-cm4",
-                feature = "stm32wl55uc-cm4",
-                feature = "stm32g491re",
-                feature = "stm32g473cc",
-                feature = "stm32u585zi",
-                feature = "stm32wle5jb"
-            )))]
-            let config_rtcsel = stm32_metapac::rtc::vals::Rtcsel(config_rtcsel);
-            #[cfg(feature = "stm32g0c1ve")]
-            let config_rtcsel = stm32_metapac::rcc::vals::Rtcsel(config_rtcsel);
+            #[cfg(not(any(rcc_wl5, rcc_wle, rcc_g4)))]
+            let config_rtcsel = Rtcsel(config_rtcsel);
 
             if !reg.rtcen() || reg.rtcsel() != config_rtcsel {
                 crate::pac::RCC.bdcr().modify(|w| w.set_bdrst(true));
@@ -195,32 +182,24 @@ impl<'d, T: Instance> super::Rtc<'d, T> {
     }
 }
 
-pub(super) unsafe fn enable_peripheral_clk() {
-    // Nothing to do
-}
+impl sealed::Instance for crate::peripherals::RTC {
+    const BACKUP_REGISTER_COUNT: usize = 32;
 
-pub const BACKUP_REGISTER_COUNT: usize = 32;
-
-/// Read content of the backup register.
-///
-/// The registers retain their values during wakes from standby mode or system resets. They also
-/// retain their value when Vdd is switched off as long as V_BAT is powered.
-pub fn read_backup_register(_rtc: &Rtc, register: usize) -> Option<u32> {
-    if register < BACKUP_REGISTER_COUNT {
-        //Some(rtc.bkpr()[register].read().bits())
-        None // RTC3 backup registers come from the TAMP peripe=heral, not RTC. Not() even in the L412 PAC
-    } else {
-        None
+    fn read_backup_register(_rtc: &Rtc, register: usize) -> Option<u32> {
+        if register < Self::BACKUP_REGISTER_COUNT {
+            //Some(rtc.bkpr()[register].read().bits())
+            None // RTC3 backup registers come from the TAMP peripe=heral, not RTC. Not() even in the L412 PAC
+        } else {
+            None
+        }
     }
-}
 
-/// Set content of the backup register.
-///
-/// The registers retain their values during wakes from standby mode or system resets. They also
-/// retain their value when Vdd is switched off as long as V_BAT is powered.
-pub fn write_backup_register(_rtc: &Rtc, register: usize, _value: u32) {
-    if register < BACKUP_REGISTER_COUNT {
-        // RTC3 backup registers come from the TAMP peripe=heral, not RTC. Not() even in the L412 PAC
-        //unsafe { self.rtc.bkpr()[register].write(|w| w.bits(value)) }
+    fn write_backup_register(_rtc: &Rtc, register: usize, _value: u32) {
+        if register < Self::BACKUP_REGISTER_COUNT {
+            // RTC3 backup registers come from the TAMP peripe=heral, not RTC. Not() even in the L412 PAC
+            //unsafe { self.rtc.bkpr()[register].write(|w| w.bits(value)) }
+        }
     }
 }
+
+impl Instance for crate::peripherals::RTC {}
diff --git a/examples/stm32f4/Cargo.toml b/examples/stm32f4/Cargo.toml
index 511a1fa8c..f5f8b632d 100644
--- a/examples/stm32f4/Cargo.toml
+++ b/examples/stm32f4/Cargo.toml
@@ -26,6 +26,7 @@ nb = "1.0.0"
 embedded-storage = "0.3.0"
 micromath = "2.0.0"
 static_cell = "1.0"
+chrono = { version = "^0.4", default-features = false}
 
 [profile.release]
 debug = 2
diff --git a/examples/stm32f4/src/bin/rtc.rs b/examples/stm32f4/src/bin/rtc.rs
new file mode 100644
index 000000000..0eca58203
--- /dev/null
+++ b/examples/stm32f4/src/bin/rtc.rs
@@ -0,0 +1,30 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+use chrono::{NaiveDate, NaiveDateTime};
+use defmt::*;
+use embassy_executor::Spawner;
+use embassy_stm32::rtc::{Rtc, RtcConfig};
+use embassy_time::{Duration, Timer};
+use {defmt_rtt as _, panic_probe as _};
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    let p = embassy_stm32::init(Default::default());
+    info!("Hello World!");
+
+    let now = NaiveDate::from_ymd_opt(2020, 5, 15)
+        .unwrap()
+        .and_hms_opt(10, 30, 15)
+        .unwrap();
+
+    let mut rtc = Rtc::new(p.RTC, RtcConfig::default());
+
+    rtc.set_datetime(now.into()).expect("datetime not set");
+
+    // In reality the delay would be much longer
+    Timer::after(Duration::from_millis(20000)).await;
+
+    let _then: NaiveDateTime = rtc.now().unwrap().into();
+}
diff --git a/tests/stm32/Cargo.toml b/tests/stm32/Cargo.toml
index 84261f8ea..d10d01e29 100644
--- a/tests/stm32/Cargo.toml
+++ b/tests/stm32/Cargo.toml
@@ -6,7 +6,7 @@ license = "MIT OR Apache-2.0"
 
 [features]
 stm32f103c8 = ["embassy-stm32/stm32f103c8"]     # Blue Pill
-stm32f429zi = ["embassy-stm32/stm32f429zi", "sdmmc"]     # Nucleo
+stm32f429zi = ["embassy-stm32/stm32f429zi", "sdmmc", "chrono"]     # Nucleo
 stm32g071rb = ["embassy-stm32/stm32g071rb"]     # Nucleo
 stm32c031c6 = ["embassy-stm32/stm32c031c6"]     # Nucleo
 stm32g491re = ["embassy-stm32/stm32g491re"]     # Nucleo
@@ -16,6 +16,7 @@ stm32h563zi = ["embassy-stm32/stm32h563zi"]     # Nucleo
 stm32u585ai = ["embassy-stm32/stm32u585ai"]     # IoT board
 
 sdmmc = []
+chrono = ["embassy-stm32/chrono", "dep:chrono"]
 
 [dependencies]
 embassy-sync = { version = "0.2.0", path = "../../embassy-sync", features = ["defmt"] }
@@ -33,6 +34,8 @@ embedded-hal-1 = { package = "embedded-hal", version = "=1.0.0-alpha.10" }
 embedded-hal-async = { version = "=0.2.0-alpha.1" }
 panic-probe = { version = "0.3.0", features = ["print-defmt"] }
 
+chrono = { version = "^0.4", default-features = false, optional = true}
+
 # BEGIN TESTS
 # Generated by gen_test.py. DO NOT EDIT.
 [[bin]]
@@ -41,6 +44,11 @@ path = "src/bin/gpio.rs"
 required-features = []
 
 [[bin]]
+name = "rtc"
+path = "src/bin/rtc.rs"
+required-features = [ "chrono",]
+
+[[bin]]
 name = "sdmmc"
 path = "src/bin/sdmmc.rs"
 required-features = [ "sdmmc",]
diff --git a/tests/stm32/src/bin/rtc.rs b/tests/stm32/src/bin/rtc.rs
new file mode 100644
index 000000000..ccf2ca609
--- /dev/null
+++ b/tests/stm32/src/bin/rtc.rs
@@ -0,0 +1,52 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+// required-features: chrono
+
+#[path = "../example_common.rs"]
+mod example_common;
+use chrono::{NaiveDate, NaiveDateTime};
+use defmt::assert;
+use embassy_executor::Spawner;
+use embassy_stm32::pac;
+use embassy_stm32::rtc::{Rtc, RtcConfig};
+use embassy_time::{Duration, Timer};
+use example_common::*;
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    let p = embassy_stm32::init(config());
+    info!("Hello World!");
+
+    let now = NaiveDate::from_ymd_opt(2020, 5, 15)
+        .unwrap()
+        .and_hms_opt(10, 30, 15)
+        .unwrap();
+
+    info!("Starting LSI");
+
+    unsafe {
+        pac::RCC.csr().modify(|w| w.set_lsion(true));
+        while !pac::RCC.csr().read().lsirdy() {}
+    }
+
+    info!("Started LSI");
+
+    let mut rtc = Rtc::new(p.RTC, RtcConfig::default());
+
+    rtc.set_datetime(now.into()).expect("datetime not set");
+
+    info!("Waiting 5 seconds");
+    Timer::after(Duration::from_millis(5000)).await;
+
+    let then: NaiveDateTime = rtc.now().unwrap().into();
+    let seconds = (then - now).num_seconds();
+
+    defmt::info!("measured = {}", seconds);
+
+    assert!(seconds > 3 && seconds < 7);
+
+    info!("Test OK");
+    cortex_m::asm::bkpt();
+}