serial: remove WordLength configuration but set it automatically based on parity

Author: mattico

CHANGELOG.md

@@ -21,6 +21,7 @@
   constants to specify how many transmit / receive buffers to include in
   `ethernet::DesRing`. To replicate the previous behaviour, use `DesRing<4, 4>`
 * spi: Utilise FIFO in `Transfer` and `Write` implementations
+* **Breaking**: manual control over serial data length removed, now set automatically based on parity
 
 ## [v0.10.0] 2021-07-xx
 

src/serial.rs

@@ -76,21 +76,12 @@ pub enum Event {
 pub mod config {
     use crate::time::Hertz;
 
-    /// The number of bits in a serial data word
-    ///
-    /// Note that the length includes the data bits and any parity bits, but not start or stop bits.
-    #[derive(Copy, Clone, PartialEq)]
-    pub enum WordLength {
-        DataBits8,
-        DataBits9,
-    }
     /// The parity bits appended to each serial data word
     ///
     /// When enabled parity bits will be automatically added by hardware on transmit, and automatically checked by
     /// hardware on receive. For example, `read()` would return [`Error::Parity`](super::Error::Parity).
     ///
-    /// Note that parity bits are included in the serial word length, so if parity is used word length should be set to
-    /// [`WordLength::DataBits9`].
+    /// Note that parity bits are included in the serial word length, so if parity is used word length will be set to 9.
     #[derive(Copy, Clone, PartialEq)]
     pub enum Parity {
         ParityNone,
@@ -135,7 +126,6 @@ pub mod config {
     #[derive(Copy, Clone)]
     pub struct Config {
         pub baudrate: Hertz,
-        pub wordlength: WordLength,
         pub parity: Parity,
         pub stopbits: StopBits,
         pub bitorder: BitOrder,
@@ -152,7 +142,6 @@ pub mod config {
         pub fn new<T: Into<Hertz>>(frequency: T) -> Self {
             Config {
                 baudrate: frequency.into(),
-                wordlength: WordLength::DataBits8,
                 parity: Parity::ParityNone,
                 stopbits: StopBits::STOP1,
                 bitorder: BitOrder::LsbFirst,
@@ -174,36 +163,22 @@ pub mod config {
 
         /// Enables Even Parity
         ///
-        /// Note that parity bits are included in the serial word length, so if parity is used word length should be set
-        /// to [`WordLength::DataBits9`].
+        /// Note that parity bits are included in the serial word length, so if parity is used word length will be set
+        /// to 9.
         pub fn parity_even(mut self) -> Self {
             self.parity = Parity::ParityEven;
             self
         }
 
         /// Enables Odd Parity
         ///
-        /// Note that parity bits are included in the serial word length, so if parity is used word length should be set
-        /// to [`WordLength::DataBits9`].
+        /// Note that parity bits are included in the serial word length, so if parity is used word length will be set
+        /// to 9.
         pub fn parity_odd(mut self) -> Self {
             self.parity = Parity::ParityOdd;
             self
         }
 
-        pub fn wordlength_8(mut self) -> Self {
-            self.wordlength = WordLength::DataBits8;
-            self
-        }
-
-        /// Set the serial word length to 9
-        ///
-        /// Note that the HAL currently only supports transmitting 8-bit serial data, so the 9th bit will always be zero
-        /// except when it is a parity bit.
-        pub fn wordlength_9(mut self) -> Self {
-            self.wordlength = WordLength::DataBits9;
-            self
-        }
-
         /// Specify the number of stop bits
         pub fn stopbits(mut self, stopbits: StopBits) -> Self {
             self.stopbits = stopbits;
@@ -617,9 +592,9 @@ macro_rules! usart {
                             .m1()
                             .clear_bit()
                             .m0()
-                            .variant(match config.wordlength {
-                                WordLength::DataBits8 => M0::BIT8,
-                                WordLength::DataBits9 => M0::BIT9,
+                            .variant(match config.parity {
+                                Parity::ParityNone => M0::BIT8,
+                                _ => M0::BIT9,
                             }).pce()
                             .variant(match config.parity {
                                 Parity::ParityNone => PCE::DISABLED,