diff --git a/embassy-stm32/src/dma/bdma.rs b/embassy-stm32/src/dma/bdma.rs
index cf1222c4..a23bb8cd 100644
--- a/embassy-stm32/src/dma/bdma.rs
+++ b/embassy-stm32/src/dma/bdma.rs
@@ -9,7 +9,8 @@ use embassy_cortex_m::interrupt::Priority;
 use embassy_hal_common::{into_ref, Peripheral, PeripheralRef};
 use embassy_sync::waitqueue::AtomicWaker;
 
-use super::{Dir, Word, WordSize};
+use super::word::{Word, WordSize};
+use super::Dir;
 use crate::_generated::BDMA_CHANNEL_COUNT;
 use crate::interrupt::{Interrupt, InterruptExt};
 use crate::pac;
@@ -167,7 +168,7 @@ impl<'a, C: Channel> Transfer<'a, C> {
             ptr as *mut u32,
             len,
             true,
-            W::bits(),
+            W::size(),
             options,
         )
     }
@@ -202,7 +203,7 @@ impl<'a, C: Channel> Transfer<'a, C> {
             ptr as *mut u32,
             len,
             true,
-            W::bits(),
+            W::size(),
             options,
         )
     }
@@ -225,7 +226,7 @@ impl<'a, C: Channel> Transfer<'a, C> {
             repeated as *const W as *mut u32,
             count,
             false,
-            W::bits(),
+            W::size(),
             options,
         )
     }
diff --git a/embassy-stm32/src/dma/dma.rs b/embassy-stm32/src/dma/dma.rs
index 62c09224..ef1d2757 100644
--- a/embassy-stm32/src/dma/dma.rs
+++ b/embassy-stm32/src/dma/dma.rs
@@ -9,7 +9,8 @@ use embassy_hal_common::{into_ref, Peripheral, PeripheralRef};
 use embassy_sync::waitqueue::AtomicWaker;
 use pac::dma::regs;
 
-use super::{Dir, Word, WordSize};
+use super::word::{Word, WordSize};
+use super::Dir;
 use crate::_generated::DMA_CHANNEL_COUNT;
 use crate::interrupt::{Interrupt, InterruptExt};
 use crate::pac::dma::vals;
@@ -246,7 +247,7 @@ impl<'a, C: Channel> Transfer<'a, C> {
             ptr as *mut u32,
             len,
             true,
-            W::bits(),
+            W::size(),
             options,
         )
     }
@@ -281,7 +282,7 @@ impl<'a, C: Channel> Transfer<'a, C> {
             ptr as *mut u32,
             len,
             true,
-            W::bits(),
+            W::size(),
             options,
         )
     }
@@ -304,7 +305,7 @@ impl<'a, C: Channel> Transfer<'a, C> {
             repeated as *const W as *mut u32,
             count,
             false,
-            W::bits(),
+            W::size(),
             options,
         )
     }
@@ -464,7 +465,7 @@ impl<'a, C: Channel, W: Word> DoubleBuffered<'a, C, W> {
         assert!(len > 0 && len <= 0xFFFF);
 
         let dir = Dir::PeripheralToMemory;
-        let data_size = W::bits();
+        let data_size = W::size();
 
         let channel_number = channel.num();
         let dma = channel.regs();
diff --git a/embassy-stm32/src/dma/gpdma.rs b/embassy-stm32/src/dma/gpdma.rs
index 5c6676a5..5a516ccd 100644
--- a/embassy-stm32/src/dma/gpdma.rs
+++ b/embassy-stm32/src/dma/gpdma.rs
@@ -9,7 +9,8 @@ use embassy_cortex_m::interrupt::Priority;
 use embassy_hal_common::{into_ref, Peripheral, PeripheralRef};
 use embassy_sync::waitqueue::AtomicWaker;
 
-use super::{Dir, Word, WordSize};
+use super::word::{Word, WordSize};
+use super::Dir;
 use crate::_generated::GPDMA_CHANNEL_COUNT;
 use crate::interrupt::{Interrupt, InterruptExt};
 use crate::pac;
@@ -165,7 +166,7 @@ impl<'a, C: Channel> Transfer<'a, C> {
             ptr as *mut u32,
             len,
             true,
-            W::bits(),
+            W::size(),
             options,
         )
     }
@@ -200,7 +201,7 @@ impl<'a, C: Channel> Transfer<'a, C> {
             ptr as *mut u32,
             len,
             true,
-            W::bits(),
+            W::size(),
             options,
         )
     }
@@ -223,7 +224,7 @@ impl<'a, C: Channel> Transfer<'a, C> {
             repeated as *const W as *mut u32,
             count,
             false,
-            W::bits(),
+            W::size(),
             options,
         )
     }
diff --git a/embassy-stm32/src/dma/mod.rs b/embassy-stm32/src/dma/mod.rs
index d29ef4a1..3312ca75 100644
--- a/embassy-stm32/src/dma/mod.rs
+++ b/embassy-stm32/src/dma/mod.rs
@@ -21,6 +21,8 @@ pub use gpdma::*;
 #[cfg(dmamux)]
 mod dmamux;
 
+pub mod word;
+
 use core::mem;
 
 use embassy_cortex_m::interrupt::Priority;
@@ -36,53 +38,6 @@ enum Dir {
     PeripheralToMemory,
 }
 
-#[derive(Debug, Copy, Clone, PartialEq, Eq)]
-#[cfg_attr(feature = "defmt", derive(defmt::Format))]
-pub enum WordSize {
-    OneByte,
-    TwoBytes,
-    FourBytes,
-}
-
-impl WordSize {
-    pub fn bytes(&self) -> usize {
-        match self {
-            Self::OneByte => 1,
-            Self::TwoBytes => 2,
-            Self::FourBytes => 4,
-        }
-    }
-}
-
-mod word_sealed {
-    pub trait Word {}
-}
-
-pub trait Word: word_sealed::Word {
-    fn bits() -> WordSize;
-}
-
-impl word_sealed::Word for u8 {}
-impl Word for u8 {
-    fn bits() -> WordSize {
-        WordSize::OneByte
-    }
-}
-
-impl word_sealed::Word for u16 {}
-impl Word for u16 {
-    fn bits() -> WordSize {
-        WordSize::TwoBytes
-    }
-}
-
-impl word_sealed::Word for u32 {}
-impl Word for u32 {
-    fn bits() -> WordSize {
-        WordSize::FourBytes
-    }
-}
-
 pub struct NoDma;
 
 impl_peripheral!(NoDma);
diff --git a/embassy-stm32/src/dma/word.rs b/embassy-stm32/src/dma/word.rs
new file mode 100644
index 00000000..aef6e970
--- /dev/null
+++ b/embassy-stm32/src/dma/word.rs
@@ -0,0 +1,79 @@
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub enum WordSize {
+    OneByte,
+    TwoBytes,
+    FourBytes,
+}
+
+impl WordSize {
+    pub fn bytes(&self) -> usize {
+        match self {
+            Self::OneByte => 1,
+            Self::TwoBytes => 2,
+            Self::FourBytes => 4,
+        }
+    }
+}
+
+mod sealed {
+    pub trait Word {}
+}
+
+pub trait Word: sealed::Word + Default + Copy + 'static {
+    fn size() -> WordSize;
+    fn bits() -> usize;
+}
+
+macro_rules! impl_word {
+    (_, $T:ident, $bits:literal, $size:ident) => {
+        impl sealed::Word for $T {}
+        impl Word for $T {
+            fn bits() -> usize {
+                $bits
+            }
+            fn size() -> WordSize {
+                WordSize::$size
+            }
+        }
+    };
+    ($T:ident, $uX:ident, $bits:literal, $size:ident) => {
+        #[repr(transparent)]
+        #[derive(Copy, Clone, Default)]
+        pub struct $T(pub $uX);
+        impl_word!(_, $T, $bits, $size);
+    };
+}
+
+impl_word!(U1, u8, 1, OneByte);
+impl_word!(U2, u8, 2, OneByte);
+impl_word!(U3, u8, 3, OneByte);
+impl_word!(U4, u8, 4, OneByte);
+impl_word!(U5, u8, 5, OneByte);
+impl_word!(U6, u8, 6, OneByte);
+impl_word!(U7, u8, 7, OneByte);
+impl_word!(_, u8, 8, OneByte);
+impl_word!(U9, u16, 9, TwoBytes);
+impl_word!(U10, u16, 10, TwoBytes);
+impl_word!(U11, u16, 11, TwoBytes);
+impl_word!(U12, u16, 12, TwoBytes);
+impl_word!(U13, u16, 13, TwoBytes);
+impl_word!(U14, u16, 14, TwoBytes);
+impl_word!(U15, u16, 15, TwoBytes);
+impl_word!(_, u16, 16, TwoBytes);
+impl_word!(U17, u32, 17, FourBytes);
+impl_word!(U18, u32, 18, FourBytes);
+impl_word!(U19, u32, 19, FourBytes);
+impl_word!(U20, u32, 20, FourBytes);
+impl_word!(U21, u32, 21, FourBytes);
+impl_word!(U22, u32, 22, FourBytes);
+impl_word!(U23, u32, 23, FourBytes);
+impl_word!(U24, u32, 24, FourBytes);
+impl_word!(U25, u32, 25, FourBytes);
+impl_word!(U26, u32, 26, FourBytes);
+impl_word!(U27, u32, 27, FourBytes);
+impl_word!(U28, u32, 28, FourBytes);
+impl_word!(U29, u32, 29, FourBytes);
+impl_word!(U30, u32, 30, FourBytes);
+impl_word!(U31, u32, 31, FourBytes);
+impl_word!(_, u32, 32, FourBytes);
diff --git a/embassy-stm32/src/spi/mod.rs b/embassy-stm32/src/spi/mod.rs
index 7858cb3e..9ce0cebf 100644
--- a/embassy-stm32/src/spi/mod.rs
+++ b/embassy-stm32/src/spi/mod.rs
@@ -7,8 +7,7 @@ use embassy_futures::join::join;
 use embassy_hal_common::{into_ref, PeripheralRef};
 pub use embedded_hal_02::spi::{Mode, Phase, Polarity, MODE_0, MODE_1, MODE_2, MODE_3};
 
-use self::sealed::WordSize;
-use crate::dma::{slice_ptr_parts, Transfer};
+use crate::dma::{slice_ptr_parts, word, Transfer};
 use crate::gpio::sealed::{AFType, Pin as _};
 use crate::gpio::{AnyPin, Pull};
 use crate::pac::spi::{regs, vals, Spi as Regs};
@@ -78,7 +77,7 @@ pub struct Spi<'d, T: Instance, Tx, Rx> {
     miso: Option<PeripheralRef<'d, AnyPin>>,
     txdma: PeripheralRef<'d, Tx>,
     rxdma: PeripheralRef<'d, Rx>,
-    current_word_size: WordSize,
+    current_word_size: word_impl::Config,
 }
 
 impl<'d, T: Instance, Tx, Rx> Spi<'d, T, Tx, Rx> {
@@ -234,14 +233,15 @@ impl<'d, T: Instance, Tx, Rx> Spi<'d, T, Tx, Rx> {
                 if mosi.is_none() {
                     w.set_rxonly(vals::Rxonly::OUTPUTDISABLED);
                 }
-                w.set_dff(WordSize::EightBit.dff())
+                w.set_dff(<u8 as sealed::Word>::CONFIG)
             });
         }
         #[cfg(spi_v2)]
         unsafe {
             T::REGS.cr2().modify(|w| {
-                w.set_frxth(WordSize::EightBit.frxth());
-                w.set_ds(WordSize::EightBit.ds());
+                let (ds, frxth) = <u8 as sealed::Word>::CONFIG;
+                w.set_frxth(frxth);
+                w.set_ds(ds);
                 w.set_ssoe(false);
             });
             T::REGS.cr1().modify(|w| {
@@ -279,7 +279,8 @@ impl<'d, T: Instance, Tx, Rx> Spi<'d, T, Tx, Rx> {
             T::REGS.cfg1().modify(|w| {
                 w.set_crcen(false);
                 w.set_mbr(br);
-                w.set_dsize(WordSize::EightBit.dsize());
+                w.set_dsize(<u8 as sealed::Word>::CONFIG);
+                w.set_fthlv(vals::Fthlv::ONEFRAME);
             });
             T::REGS.cr2().modify(|w| {
                 w.set_tsize(0);
@@ -297,7 +298,7 @@ impl<'d, T: Instance, Tx, Rx> Spi<'d, T, Tx, Rx> {
             miso,
             txdma,
             rxdma,
-            current_word_size: WordSize::EightBit,
+            current_word_size: <u8 as sealed::Word>::CONFIG,
         }
     }
 
@@ -355,7 +356,7 @@ impl<'d, T: Instance, Tx, Rx> Spi<'d, T, Tx, Rx> {
         }
     }
 
-    fn set_word_size(&mut self, word_size: WordSize) {
+    fn set_word_size(&mut self, word_size: word_impl::Config) {
         if self.current_word_size == word_size {
             return;
         }
@@ -364,7 +365,7 @@ impl<'d, T: Instance, Tx, Rx> Spi<'d, T, Tx, Rx> {
         unsafe {
             T::REGS.cr1().modify(|reg| {
                 reg.set_spe(false);
-                reg.set_dff(word_size.dff())
+                reg.set_dff(word_size)
             });
             T::REGS.cr1().modify(|reg| {
                 reg.set_spe(true);
@@ -376,8 +377,8 @@ impl<'d, T: Instance, Tx, Rx> Spi<'d, T, Tx, Rx> {
                 w.set_spe(false);
             });
             T::REGS.cr2().modify(|w| {
-                w.set_frxth(word_size.frxth());
-                w.set_ds(word_size.ds());
+                w.set_frxth(word_size.1);
+                w.set_ds(word_size.0);
             });
             T::REGS.cr1().modify(|w| {
                 w.set_spe(true);
@@ -393,7 +394,7 @@ impl<'d, T: Instance, Tx, Rx> Spi<'d, T, Tx, Rx> {
                 w.set_spe(false);
             });
             T::REGS.cfg1().modify(|w| {
-                w.set_dsize(word_size.dsize());
+                w.set_dsize(word_size);
             });
             T::REGS.cr1().modify(|w| {
                 w.set_csusp(false);
@@ -412,7 +413,7 @@ impl<'d, T: Instance, Tx, Rx> Spi<'d, T, Tx, Rx> {
             return Ok(());
         }
 
-        self.set_word_size(W::WORDSIZE);
+        self.set_word_size(W::CONFIG);
         unsafe {
             T::REGS.cr1().modify(|w| {
                 w.set_spe(false);
@@ -450,7 +451,7 @@ impl<'d, T: Instance, Tx, Rx> Spi<'d, T, Tx, Rx> {
             return Ok(());
         }
 
-        self.set_word_size(W::WORDSIZE);
+        self.set_word_size(W::CONFIG);
         unsafe {
             T::REGS.cr1().modify(|w| {
                 w.set_spe(false);
@@ -513,7 +514,7 @@ impl<'d, T: Instance, Tx, Rx> Spi<'d, T, Tx, Rx> {
             return Ok(());
         }
 
-        self.set_word_size(W::WORDSIZE);
+        self.set_word_size(W::CONFIG);
         unsafe {
             T::REGS.cr1().modify(|w| {
                 w.set_spe(false);
@@ -571,7 +572,7 @@ impl<'d, T: Instance, Tx, Rx> Spi<'d, T, Tx, Rx> {
     pub fn blocking_write<W: Word>(&mut self, words: &[W]) -> Result<(), Error> {
         unsafe { T::REGS.cr1().modify(|w| w.set_spe(true)) }
         flush_rx_fifo(T::REGS);
-        self.set_word_size(W::WORDSIZE);
+        self.set_word_size(W::CONFIG);
         for word in words.iter() {
             let _ = transfer_word(T::REGS, *word)?;
         }
@@ -581,7 +582,7 @@ impl<'d, T: Instance, Tx, Rx> Spi<'d, T, Tx, Rx> {
     pub fn blocking_read<W: Word>(&mut self, words: &mut [W]) -> Result<(), Error> {
         unsafe { T::REGS.cr1().modify(|w| w.set_spe(true)) }
         flush_rx_fifo(T::REGS);
-        self.set_word_size(W::WORDSIZE);
+        self.set_word_size(W::CONFIG);
         for word in words.iter_mut() {
             *word = transfer_word(T::REGS, W::default())?;
         }
@@ -591,7 +592,7 @@ impl<'d, T: Instance, Tx, Rx> Spi<'d, T, Tx, Rx> {
     pub fn blocking_transfer_in_place<W: Word>(&mut self, words: &mut [W]) -> Result<(), Error> {
         unsafe { T::REGS.cr1().modify(|w| w.set_spe(true)) }
         flush_rx_fifo(T::REGS);
-        self.set_word_size(W::WORDSIZE);
+        self.set_word_size(W::CONFIG);
         for word in words.iter_mut() {
             *word = transfer_word(T::REGS, *word)?;
         }
@@ -601,7 +602,7 @@ impl<'d, T: Instance, Tx, Rx> Spi<'d, T, Tx, Rx> {
     pub fn blocking_transfer<W: Word>(&mut self, read: &mut [W], write: &[W]) -> Result<(), Error> {
         unsafe { T::REGS.cr1().modify(|w| w.set_spe(true)) }
         flush_rx_fifo(T::REGS);
-        self.set_word_size(W::WORDSIZE);
+        self.set_word_size(W::CONFIG);
         let len = read.len().max(write.len());
         for i in 0..len {
             let wb = write.get(i).copied().unwrap_or_default();
@@ -933,70 +934,89 @@ pub(crate) mod sealed {
         const REGS: Regs;
     }
 
-    pub trait Word: Copy + 'static {
-        const WORDSIZE: WordSize;
-    }
-
-    impl Word for u8 {
-        const WORDSIZE: WordSize = WordSize::EightBit;
-    }
-    impl Word for u16 {
-        const WORDSIZE: WordSize = WordSize::SixteenBit;
-    }
-
-    #[derive(Copy, Clone, PartialOrd, PartialEq)]
-    pub enum WordSize {
-        EightBit,
-        SixteenBit,
-    }
-
-    impl WordSize {
-        #[cfg(any(spi_v1, spi_f1))]
-        pub fn dff(&self) -> vals::Dff {
-            match self {
-                WordSize::EightBit => vals::Dff::EIGHTBIT,
-                WordSize::SixteenBit => vals::Dff::SIXTEENBIT,
-            }
-        }
-
-        #[cfg(spi_v2)]
-        pub fn ds(&self) -> vals::Ds {
-            match self {
-                WordSize::EightBit => vals::Ds::EIGHTBIT,
-                WordSize::SixteenBit => vals::Ds::SIXTEENBIT,
-            }
-        }
-
-        #[cfg(spi_v2)]
-        pub fn frxth(&self) -> vals::Frxth {
-            match self {
-                WordSize::EightBit => vals::Frxth::QUARTER,
-                WordSize::SixteenBit => vals::Frxth::HALF,
-            }
-        }
-
-        #[cfg(any(spi_v3, spi_v4, spi_v5))]
-        pub fn dsize(&self) -> u8 {
-            match self {
-                WordSize::EightBit => 0b0111,
-                WordSize::SixteenBit => 0b1111,
-            }
-        }
-
-        #[cfg(any(spi_v3, spi_v4, spi_v5))]
-        pub fn _frxth(&self) -> vals::Fthlv {
-            match self {
-                WordSize::EightBit => vals::Fthlv::ONEFRAME,
-                WordSize::SixteenBit => vals::Fthlv::ONEFRAME,
-            }
-        }
+    pub trait Word {
+        const CONFIG: word_impl::Config;
     }
 }
 
-pub trait Word: Copy + 'static + sealed::Word + Default + crate::dma::Word {}
+pub trait Word: word::Word + sealed::Word {}
 
-impl Word for u8 {}
-impl Word for u16 {}
+macro_rules! impl_word {
+    ($T:ty, $config:expr) => {
+        impl sealed::Word for $T {
+            const CONFIG: Config = $config;
+        }
+        impl Word for $T {}
+    };
+}
+
+#[cfg(any(spi_v1, spi_f1))]
+mod word_impl {
+    use super::*;
+
+    pub type Config = vals::Dff;
+
+    impl_word!(u8, vals::Dff::EIGHTBIT);
+    impl_word!(u16, vals::Dff::SIXTEENBIT);
+}
+
+#[cfg(any(spi_v2))]
+mod word_impl {
+    use super::*;
+
+    pub type Config = (vals::Ds, vals::Frxth);
+
+    impl_word!(word::U4, (vals::Ds::FOURBIT, vals::Frxth::QUARTER));
+    impl_word!(word::U5, (vals::Ds::FIVEBIT, vals::Frxth::QUARTER));
+    impl_word!(word::U6, (vals::Ds::SIXBIT, vals::Frxth::QUARTER));
+    impl_word!(word::U7, (vals::Ds::SEVENBIT, vals::Frxth::QUARTER));
+    impl_word!(u8, (vals::Ds::EIGHTBIT, vals::Frxth::QUARTER));
+    impl_word!(word::U9, (vals::Ds::NINEBIT, vals::Frxth::HALF));
+    impl_word!(word::U10, (vals::Ds::TENBIT, vals::Frxth::HALF));
+    impl_word!(word::U11, (vals::Ds::ELEVENBIT, vals::Frxth::HALF));
+    impl_word!(word::U12, (vals::Ds::TWELVEBIT, vals::Frxth::HALF));
+    impl_word!(word::U13, (vals::Ds::THIRTEENBIT, vals::Frxth::HALF));
+    impl_word!(word::U14, (vals::Ds::FOURTEENBIT, vals::Frxth::HALF));
+    impl_word!(word::U15, (vals::Ds::FIFTEENBIT, vals::Frxth::HALF));
+    impl_word!(u16, (vals::Ds::SIXTEENBIT, vals::Frxth::HALF));
+}
+
+#[cfg(any(spi_v3, spi_v4, spi_v5))]
+mod word_impl {
+    use super::*;
+
+    pub type Config = u8;
+
+    impl_word!(word::U4, 4 - 1);
+    impl_word!(word::U5, 5 - 1);
+    impl_word!(word::U6, 6 - 1);
+    impl_word!(word::U7, 7 - 1);
+    impl_word!(u8, 8 - 1);
+    impl_word!(word::U9, 9 - 1);
+    impl_word!(word::U10, 10 - 1);
+    impl_word!(word::U11, 11 - 1);
+    impl_word!(word::U12, 12 - 1);
+    impl_word!(word::U13, 13 - 1);
+    impl_word!(word::U14, 14 - 1);
+    impl_word!(word::U15, 15 - 1);
+    impl_word!(u16, 16 - 1);
+    impl_word!(word::U17, 17 - 1);
+    impl_word!(word::U18, 18 - 1);
+    impl_word!(word::U19, 19 - 1);
+    impl_word!(word::U20, 20 - 1);
+    impl_word!(word::U21, 21 - 1);
+    impl_word!(word::U22, 22 - 1);
+    impl_word!(word::U23, 23 - 1);
+    impl_word!(word::U24, 24 - 1);
+    impl_word!(word::U25, 25 - 1);
+    impl_word!(word::U26, 26 - 1);
+    impl_word!(word::U27, 27 - 1);
+    impl_word!(word::U28, 28 - 1);
+    impl_word!(word::U29, 29 - 1);
+    impl_word!(word::U30, 30 - 1);
+    impl_word!(word::U31, 31 - 1);
+    impl_word!(u32, 32 - 1);
+}
 
 pub trait Instance: Peripheral<P = Self> + sealed::Instance + RccPeripheral {}
 pin_trait!(SckPin, Instance);