diff --git a/embassy-stm32/build.rs b/embassy-stm32/build.rs
index df8af660..a6434a7e 100644
--- a/embassy-stm32/build.rs
+++ b/embassy-stm32/build.rs
@@ -9,7 +9,7 @@ fn main() {
         .expect("No stm32xx Cargo feature enabled")
         .strip_prefix("CARGO_FEATURE_")
         .unwrap()
-        .to_ascii_uppercase();
+        .to_ascii_lowercase();
 
     let out_dir = &PathBuf::from(env::var_os("OUT_DIR").unwrap());
     let out_file = out_dir.join("generated.rs").to_string_lossy().to_string();
@@ -30,6 +30,15 @@ fn main() {
         };
     );
 
+    let mut chip_and_core = chip_name.split('_');
+    let chip = chip_and_core.next().expect("Unexpected stm32xx feature");
+
+    if let Some(core) = chip_and_core.next() {
+        println!("cargo:rustc-cfg={}_{}", &chip[..(chip.len() - 2)], core);
+    } else {
+        println!("cargo:rustc-cfg={}", &chip[..(chip.len() - 2)]);
+    }
+
     println!("cargo:rerun-if-changed=build.rs");
     println!("cargo:rerun-if-changed=gen.py");
 }
diff --git a/embassy-stm32/src/pwr/none.rs b/embassy-stm32/src/pwr/f4.rs
similarity index 100%
rename from embassy-stm32/src/pwr/none.rs
rename to embassy-stm32/src/pwr/f4.rs
diff --git a/embassy-stm32/src/pwr/mod.rs b/embassy-stm32/src/pwr/mod.rs
index f0d47ca8..1bb104bd 100644
--- a/embassy-stm32/src/pwr/mod.rs
+++ b/embassy-stm32/src/pwr/mod.rs
@@ -1,5 +1,5 @@
 #[cfg_attr(any(pwr_h7, pwr_h7smps), path = "h7.rs")]
-#[cfg_attr(not(any(pwr_h7, pwr_h7smps)), path = "none.rs")]
+#[cfg_attr(pwr_f4, path = "f4.rs")]
 mod _version;
 
 pub use _version::*;
diff --git a/embassy-stm32/src/rcc/f4/max.rs b/embassy-stm32/src/rcc/f4/max.rs
index 03e1e983..dd8de3da 100644
--- a/embassy-stm32/src/rcc/f4/max.rs
+++ b/embassy-stm32/src/rcc/f4/max.rs
@@ -1,268 +1,21 @@
-#[cfg(any(
-    feature = "stm32f401cb",
-    feature = "stm32f401cc",
-    feature = "stm32f401cd",
-    feature = "stm32f401ce",
-    feature = "stm32f401rb",
-    feature = "stm32f401rc",
-    feature = "stm32f401rd",
-    feature = "stm32f401re",
-    feature = "stm32f401vb",
-    feature = "stm32f401vc",
-    feature = "stm32f401vd",
-    feature = "stm32f401ve",
-))]
+#[cfg(stm32f401)]
 pub(crate) const SYSCLK_MAX: u32 = 84_000_000;
 
-#[cfg(any(
-    feature = "stm32f405oe",
-    feature = "stm32f405og",
-    feature = "stm32f405rg",
-    feature = "stm32f405vg",
-    feature = "stm32f405zg",
-    feature = "stm32f407ie",
-    feature = "stm32f407ig",
-    feature = "stm32f407ve",
-    feature = "stm32f407vg",
-    feature = "stm32f407ze",
-    feature = "stm32f407zg",
-    feature = "stm32f415og",
-    feature = "stm32f415rg",
-    feature = "stm32f415vg",
-    feature = "stm32f415zg",
-    feature = "stm32f417ie",
-    feature = "stm32f417ig",
-    feature = "stm32f417ve",
-    feature = "stm32f417vg",
-    feature = "stm32f417ze",
-    feature = "stm32f417zg",
-))]
+#[cfg(any(stm32f405, stm32f407, stm32f415, stm32f417,))]
 pub(crate) const SYSCLK_MAX: u32 = 168_000_000;
 
-#[cfg(any(
-    feature = "stm32f410c8",
-    feature = "stm32f410cb",
-    feature = "stm32f410r8",
-    feature = "stm32f410rb",
-    feature = "stm32f410t8",
-    feature = "stm32f410tb",
-    feature = "stm32f411cc",
-    feature = "stm32f411ce",
-    feature = "stm32f411rc",
-    feature = "stm32f411re",
-    feature = "stm32f411vc",
-    feature = "stm32f411ve",
-    feature = "stm32f412ce",
-    feature = "stm32f412cg",
-    feature = "stm32f412re",
-    feature = "stm32f412rg",
-    feature = "stm32f412ve",
-    feature = "stm32f412vg",
-    feature = "stm32f412ze",
-    feature = "stm32f412zg",
-    feature = "stm32f413cg",
-    feature = "stm32f413ch",
-    feature = "stm32f413mg",
-    feature = "stm32f413mh",
-    feature = "stm32f413rg",
-    feature = "stm32f413rh",
-    feature = "stm32f413vg",
-    feature = "stm32f413vh",
-    feature = "stm32f413zg",
-    feature = "stm32f413zh",
-    feature = "stm32f423ch",
-    feature = "stm32f423mh",
-    feature = "stm32f423rh",
-    feature = "stm32f423vh",
-    feature = "stm32f423zh",
-))]
+#[cfg(any(stm32f410, stm32f411, stm32f412, stm32f413, stm32f423,))]
 pub(crate) const SYSCLK_MAX: u32 = 100_000_000;
 
 #[cfg(any(
-    feature = "stm32f427ag",
-    feature = "stm32f427ai",
-    feature = "stm32f427ig",
-    feature = "stm32f427ii",
-    feature = "stm32f427vg",
-    feature = "stm32f427vi",
-    feature = "stm32f427zg",
-    feature = "stm32f427zi",
-    feature = "stm32f429ag",
-    feature = "stm32f429ai",
-    feature = "stm32f429be",
-    feature = "stm32f429bg",
-    feature = "stm32f429bi",
-    feature = "stm32f429ie",
-    feature = "stm32f429ig",
-    feature = "stm32f429ii",
-    feature = "stm32f429ne",
-    feature = "stm32f429ng",
-    feature = "stm32f429ni",
-    feature = "stm32f429ve",
-    feature = "stm32f429vg",
-    feature = "stm32f429vi",
-    feature = "stm32f429ze",
-    feature = "stm32f429zg",
-    feature = "stm32f429zi",
-    feature = "stm32f437ai",
-    feature = "stm32f437ig",
-    feature = "stm32f437ii",
-    feature = "stm32f437vg",
-    feature = "stm32f437vi",
-    feature = "stm32f437zg",
-    feature = "stm32f437zi",
-    feature = "stm32f439ai",
-    feature = "stm32f439bg",
-    feature = "stm32f439bi",
-    feature = "stm32f439ig",
-    feature = "stm32f439ii",
-    feature = "stm32f439ng",
-    feature = "stm32f439ni",
-    feature = "stm32f439vg",
-    feature = "stm32f439vi",
-    feature = "stm32f439zg",
-    feature = "stm32f439zi",
-    feature = "stm32f446mc",
-    feature = "stm32f446me",
-    feature = "stm32f446rc",
-    feature = "stm32f446re",
-    feature = "stm32f446vc",
-    feature = "stm32f446ve",
-    feature = "stm32f446zc",
-    feature = "stm32f446ze",
-    feature = "stm32f469ae",
-    feature = "stm32f469ag",
-    feature = "stm32f469ai",
-    feature = "stm32f469be",
-    feature = "stm32f469bg",
-    feature = "stm32f469bi",
-    feature = "stm32f469ie",
-    feature = "stm32f469ig",
-    feature = "stm32f469ii",
-    feature = "stm32f469ne",
-    feature = "stm32f469ng",
-    feature = "stm32f469ni",
-    feature = "stm32f469ve",
-    feature = "stm32f469vg",
-    feature = "stm32f469vi",
-    feature = "stm32f469ze",
-    feature = "stm32f469zg",
-    feature = "stm32f469zi",
-    feature = "stm32f479ag",
-    feature = "stm32f479ai",
-    feature = "stm32f479bg",
-    feature = "stm32f479bi",
-    feature = "stm32f479ig",
-    feature = "stm32f479ii",
-    feature = "stm32f479ng",
-    feature = "stm32f479ni",
-    feature = "stm32f479vg",
-    feature = "stm32f479vi",
-    feature = "stm32f479zg",
-    feature = "stm32f479zi",
+    stm32f427, stm32f429, stm32f437, stm32f439, stm32f446, stm32f469, stm32f479,
 ))]
 pub(crate) const SYSCLK_MAX: u32 = 180_000_000;
 
-#[cfg(any(
-    feature = "stm32f401cb",
-    feature = "stm32f401cc",
-    feature = "stm32f401cd",
-    feature = "stm32f401ce",
-    feature = "stm32f401rb",
-    feature = "stm32f401rc",
-    feature = "stm32f401rd",
-    feature = "stm32f401re",
-    feature = "stm32f401vb",
-    feature = "stm32f401vc",
-    feature = "stm32f401vd",
-    feature = "stm32f401ve",
-    feature = "stm32f410c8",
-    feature = "stm32f410cb",
-    feature = "stm32f410r8",
-    feature = "stm32f410rb",
-    feature = "stm32f410t8",
-    feature = "stm32f410tb",
-    feature = "stm32f411cc",
-    feature = "stm32f411ce",
-    feature = "stm32f411rc",
-    feature = "stm32f411re",
-    feature = "stm32f411vc",
-    feature = "stm32f411ve",
-    feature = "stm32f412ce",
-    feature = "stm32f412cg",
-    feature = "stm32f412re",
-    feature = "stm32f412rg",
-    feature = "stm32f412ve",
-    feature = "stm32f412vg",
-    feature = "stm32f412ze",
-    feature = "stm32f412zg",
-    feature = "stm32f413cg",
-    feature = "stm32f413ch",
-    feature = "stm32f413mg",
-    feature = "stm32f413mh",
-    feature = "stm32f413rg",
-    feature = "stm32f413rh",
-    feature = "stm32f413vg",
-    feature = "stm32f413vh",
-    feature = "stm32f413zg",
-    feature = "stm32f413zh",
-    feature = "stm32f423ch",
-    feature = "stm32f423mh",
-    feature = "stm32f423rh",
-    feature = "stm32f423vh",
-    feature = "stm32f423zh",
-))]
+#[cfg(any(stm32f401, stm32f410, stm32f411, stm32f412, stm32f413, stm32f423,))]
 pub(crate) const PCLK2_MAX: u32 = SYSCLK_MAX;
 
-#[cfg(not(any(
-    feature = "stm32f401cb",
-    feature = "stm32f401cc",
-    feature = "stm32f401cd",
-    feature = "stm32f401ce",
-    feature = "stm32f401rb",
-    feature = "stm32f401rc",
-    feature = "stm32f401rd",
-    feature = "stm32f401re",
-    feature = "stm32f401vb",
-    feature = "stm32f401vc",
-    feature = "stm32f401vd",
-    feature = "stm32f401ve",
-    feature = "stm32f410c8",
-    feature = "stm32f410cb",
-    feature = "stm32f410r8",
-    feature = "stm32f410rb",
-    feature = "stm32f410t8",
-    feature = "stm32f410tb",
-    feature = "stm32f411cc",
-    feature = "stm32f411ce",
-    feature = "stm32f411rc",
-    feature = "stm32f411re",
-    feature = "stm32f411vc",
-    feature = "stm32f411ve",
-    feature = "stm32f412ce",
-    feature = "stm32f412cg",
-    feature = "stm32f412re",
-    feature = "stm32f412rg",
-    feature = "stm32f412ve",
-    feature = "stm32f412vg",
-    feature = "stm32f412ze",
-    feature = "stm32f412zg",
-    feature = "stm32f413cg",
-    feature = "stm32f413ch",
-    feature = "stm32f413mg",
-    feature = "stm32f413mh",
-    feature = "stm32f413rg",
-    feature = "stm32f413rh",
-    feature = "stm32f413vg",
-    feature = "stm32f413vh",
-    feature = "stm32f413zg",
-    feature = "stm32f413zh",
-    feature = "stm32f423ch",
-    feature = "stm32f423mh",
-    feature = "stm32f423rh",
-    feature = "stm32f423vh",
-    feature = "stm32f423zh",
-)))]
+#[cfg(not(any(stm32f401, stm32f410, stm32f411, stm32f412, stm32f413, stm32f423,)))]
 pub(crate) const PCLK2_MAX: u32 = SYSCLK_MAX / 2;
 
 pub(crate) const PCLK1_MAX: u32 = PCLK2_MAX / 2;