rp/pio: add set-pin-{values,dirs} convenience functions

these are needed a lot during state machine setup, it makes sense to
provide convenience functions for them.

embassy-rp/src/pio.rs

@@ -13,7 +13,7 @@ use pio::{SideSet, Wrap};
 
 use crate::dma::{Channel, Transfer, Word};
 use crate::gpio::sealed::Pin as SealedPin;
-use crate::gpio::{self, AnyPin, Drive, Pull, SlewRate};
+use crate::gpio::{self, AnyPin, Drive, Level, Pull, SlewRate};
 use crate::pac::dma::vals::TreqSel;
 use crate::relocate::RelocatedProgram;
 use crate::{interrupt, pac, peripherals, pio_instr_util, RegExt};
@@ -54,6 +54,14 @@ pub enum ShiftDirection {
     Left = 0,
 }
 
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[repr(u8)]
+pub enum Direction {
+    In = 0,
+    Out = 1,
+}
+
 const RXNEMPTY_MASK: u32 = 1 << 0;
 const TXNFULL_MASK: u32 = 1 << 4;
 const SMIRQ_MASK: u32 = 1 << 8;
@@ -533,6 +541,56 @@ impl<'d, PIO: Instance + 'd, const SM: usize> StateMachine<'d, PIO, SM> {
         }
     }
 
+    fn with_paused(&mut self, f: impl FnOnce(&mut Self)) {
+        let enabled = self.is_enabled();
+        self.set_enable(false);
+        let pincfg = unsafe { Self::this_sm().pinctrl().read() };
+        let execcfg = unsafe { Self::this_sm().execctrl().read() };
+        unsafe {
+            Self::this_sm().execctrl().write_clear(|w| w.set_out_sticky(true));
+        }
+        f(self);
+        unsafe {
+            Self::this_sm().pinctrl().write_value(pincfg);
+            Self::this_sm().execctrl().write_value(execcfg);
+        }
+        self.set_enable(enabled);
+    }
+
+    /// Sets pin directions. This pauses the current state machine to run `SET` commands
+    /// and temporarily unsets the `OUT_STICKY` bit.
+    pub fn set_pin_dirs(&mut self, dir: Direction, pins: &[&Pin<'d, PIO>]) {
+        self.with_paused(|sm| {
+            for pin in pins {
+                unsafe {
+                    Self::this_sm().pinctrl().write(|w| {
+                        w.set_set_base(pin.pin());
+                        w.set_set_count(1);
+                    });
+                    // SET PINDIRS, (dir)
+                    sm.exec_instr(0b111_00000_100_00000 | dir as u16);
+                }
+            }
+        });
+    }
+
+    /// Sets pin output values. This pauses the current state machine to run
+    /// `SET` commands and temporarily unsets the `OUT_STICKY` bit.
+    pub fn set_pins(&mut self, level: Level, pins: &[&Pin<'d, PIO>]) {
+        self.with_paused(|sm| {
+            for pin in pins {
+                unsafe {
+                    Self::this_sm().pinctrl().write(|w| {
+                        w.set_set_base(pin.pin());
+                        w.set_set_count(1);
+                    });
+                    // SET PINS, (dir)
+                    sm.exec_instr(0b111_00000_000_00000 | level as u16);
+                }
+            }
+        });
+    }
+
     pub fn set_jmp_pin(&mut self, pin: u8) {
         unsafe {
             Self::this_sm().execctrl().modify(|w| w.set_jmp_pin(pin));

examples/rp/src/bin/pio_hd44780.rs

@@ -7,7 +7,7 @@ use core::fmt::Write;
 use embassy_executor::Spawner;
 use embassy_rp::dma::{AnyChannel, Channel};
 use embassy_rp::peripherals::PIO0;
-use embassy_rp::pio::{FifoJoin, Pio, PioPin, ShiftDirection, StateMachine};
+use embassy_rp::pio::{Direction, FifoJoin, Pio, PioPin, ShiftDirection, StateMachine};
 use embassy_rp::pwm::{Config, Pwm};
 use embassy_rp::relocate::RelocatedProgram;
 use embassy_rp::{into_ref, Peripheral, PeripheralRef};
@@ -115,12 +115,7 @@ impl<'l> HD44780<'l> {
         let db6 = common.make_pio_pin(db6);
         let db7 = common.make_pio_pin(db7);
 
-        sm0.set_set_pins(&[&rs, &rw]);
+        sm0.set_pin_dirs(Direction::Out, &[&rs, &rw, &e, &db4, &db5, &db6, &db7]);
-        embassy_rp::pio_instr_util::set_pindir(&mut sm0, 0b11);
-        sm0.set_set_pins(&[&e]);
-        embassy_rp::pio_instr_util::set_pindir(&mut sm0, 0b1);
-        sm0.set_set_pins(&[&db4, &db5, &db6, &db7]);
-        embassy_rp::pio_instr_util::set_pindir(&mut sm0, 0b11111);
 
         let relocated = RelocatedProgram::new(&prg.program);
         sm0.use_program(&common.load_program(&relocated), &[&e]);