From 8e151273b597f4e2cada17b5bcfc73a687af8d7a Mon Sep 17 00:00:00 2001
From: Wilfried Chauveau <wilfried.chauveau@ithinuel.me>
Date: Wed, 18 Oct 2023 19:08:39 +0100
Subject: [PATCH] Implement `send_break` support

---
 rp2040-hal/src/uart/peripheral.rs | 34 +++++++++++++++++++++++++++++++
 rp2040-hal/src/uart/writer.rs     | 34 +++++++++++++++++++++++++++++++
 2 files changed, 68 insertions(+)

diff --git a/rp2040-hal/src/uart/peripheral.rs b/rp2040-hal/src/uart/peripheral.rs
index 70fffbccb..160c56bc1 100644
--- a/rp2040-hal/src/uart/peripheral.rs
+++ b/rp2040-hal/src/uart/peripheral.rs
@@ -200,6 +200,40 @@ impl<D: UartDevice, P: ValidUartPinout<D>> UartPeripheral<Enabled, D, P> {
         super::reader::read_full_blocking(&self.device, buffer)
     }
 
+    /// Initiates a break
+    ///
+    /// If transmitting, this takes effect immediately after the current byte has completed.  
+    /// For proper execution of the break command, this must be held for at least 2 complete frames
+    /// worth of time.
+    ///
+    /// <div class="warning">The device won’t be able to send anything while breaking.</div>
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// # use rp2040_hal::uart::{Pins, ValidUartPinout, Enabled, UartPeripheral};
+    /// # use rp2040_hal::pac::UART0;
+    /// # use rp2040_hal::typelevel::OptionTNone;
+    /// # use embedded_hal_0_2::blocking::delay::DelayUs;
+    /// # type PINS = Pins<OptionTNone, OptionTNone, OptionTNone, OptionTNone>;
+    /// # let mut serial: UartPeripheral<Enabled, UART0, PINS> = unsafe { core::mem::zeroed() };
+    /// # let mut timer: rp2040_hal::Timer = unsafe { core::mem::zeroed() };
+    /// serial.lowlevel_break_start();
+    /// // at 115_200Bps on 8N1 configuration, 20bits takes (20*10⁶)/115200 = 173.611…μs.
+    /// timer.delay_us(175);
+    /// serial.lowlevel_break_stop();
+    /// ```
+    pub fn lowlevel_break_start(&mut self) {
+        self.device.uartlcr_h().modify(|_, w| w.brk().set_bit());
+    }
+
+    /// Terminates a break condition.
+    ///
+    /// See `lowlevel_break_start` for more details.
+    pub fn lowlevel_break_stop(&mut self) {
+        self.device.uartlcr_h().modify(|_, w| w.brk().clear_bit());
+    }
+
     /// Join the reader and writer halves together back into the original Uart peripheral.
     ///
     /// A reader/writer pair can be obtained by calling [`split`].
diff --git a/rp2040-hal/src/uart/writer.rs b/rp2040-hal/src/uart/writer.rs
index d90072a59..4e5a930f2 100644
--- a/rp2040-hal/src/uart/writer.rs
+++ b/rp2040-hal/src/uart/writer.rs
@@ -172,6 +172,40 @@ impl<D: UartDevice, P: ValidUartPinout<D>> Writer<D, P> {
     pub fn disable_tx_interrupt(&mut self) {
         disable_tx_interrupt(&self.device)
     }
+
+    /// Initiates a break
+    ///
+    /// If transmitting, this takes effect immediately after the current byte has completed.  
+    /// For proper execution of the break command, this must be held for at least 2 complete frames
+    /// worth of time.
+    ///
+    /// <div class="warning">The device won’t be able to send anything while breaking.</div>
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// # use rp2040_hal::uart::{Pins, ValidUartPinout, Enabled, UartPeripheral};
+    /// # use rp2040_hal::pac::UART0;
+    /// # use rp2040_hal::typelevel::OptionTNone;
+    /// # use embedded_hal_0_2::blocking::delay::DelayUs;
+    /// # type PINS = Pins<OptionTNone, OptionTNone, OptionTNone, OptionTNone>;
+    /// # let mut serial: UartPeripheral<Enabled, UART0, PINS> = unsafe { core::mem::zeroed() };
+    /// # let mut timer: rp2040_hal::Timer = unsafe { core::mem::zeroed() };
+    /// serial.lowlevel_break_start();
+    /// // at 115_200Bps on 8N1 configuration, 20bits takes (20*10⁶)/115200 = 173.611…μs.
+    /// timer.delay_us(175);
+    /// serial.lowlevel_break_stop();
+    /// ```
+    pub fn lowlevel_break_start(&mut self) {
+        self.device.uartlcr_h().modify(|_, w| w.brk().set_bit());
+    }
+
+    /// Terminates a break condition.
+    ///
+    /// See `lowlevel_break_start` for more details.
+    pub fn lowlevel_break_stop(&mut self) {
+        self.device.uartlcr_h().modify(|_, w| w.brk().clear_bit());
+    }
 }
 
 impl<D: UartDevice, P: ValidUartPinout<D>> Write02<u8> for Writer<D, P> {