stm32/rtc: cleanup and consolidate

15 files changed, 110 insertions, 438 deletions

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..c2f07a066 100644
--- a/embassy-stm32/src/rtc/mod.rs
+++ b/embassy-stm32/src/rtc/mod.rs
@@ -10,7 +10,7 @@ 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;
diff --git a/embassy-stm32/src/rtc/v2/mod.rs b/embassy-stm32/src/rtc/v2.rs
index 296adae89..abf3da3be 100644
--- a/embassy-stm32/src/rtc/v2/mod.rs
+++ b/embassy-stm32/src/rtc/v2.rs
@@ -3,20 +3,6 @@ use stm32_metapac::rtc::vals::{Init, Osel, Pol};
 use super::{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
@@ -169,3 +155,81 @@ pub fn write_backup_register(rtc: &Rtc, register: usize, value: u32) {
         unsafe { rtc.bkpr(register).write(|w| w.set_bkp(value)) }
     }
 }
+
+pub(crate) unsafe fn enable_peripheral_clk() {
+    #[cfg(any(rtc_v2f0, rtc_v2f7, 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();
+    }
+}
+
+pub const BACKUP_REGISTER_COUNT: usize = 20;
+
+pub(super) unsafe fn unlock_backup_domain(clock_config: 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_v2f0, rtc_v2f4, rtc_v2f7, rtc_v2h7, rtc_v2l4, rtc_v2wb))]
+    let cr = crate::pac::PWR.cr1();
+
+    // TODO: Missing from PAC for l0?
+    #[cfg(not(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_v2f0, rtc_v2f7, 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_v2f0, rtc_v2f7, rtc_v2l4, rtc_v2wb))]
+            w.set_lscosel(reg.lscosel());
+            #[cfg(any(rtc_v2f0, rtc_v2f7, 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());
+        });
+    }
+}
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/examples/stm32f4/Cargo.toml b/examples/stm32f4/Cargo.toml
index 69dcab64c..275c2c1a7 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();
+}