Merge pull request #4824 from mikeytdisco/onewire_fix

Disable PIO SM before setting Y register

2 files changed, 16 insertions, 3 deletions

diff --git a/embassy-rp/CHANGELOG.md b/embassy-rp/CHANGELOG.md
index 57ec13658..4fab20f08 100644
--- a/embassy-rp/CHANGELOG.md
+++ b/embassy-rp/CHANGELOG.md
@@ -15,6 +15,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - add `wait_for_alarm` and `alarm_scheduled` methods to rtc module ([#4216](https://github.com/embassy-rs/embassy/pull/4216))
 - rp235x: use msplim for stack guard instead of MPU
 - Add reset_to_usb_boot for rp235x ([#4705](https://github.com/embassy-rs/embassy/pull/4705))
+- Add fix #4822 in PIO onewire. Change to disable the state machine before setting y register ([#4824](https://github.com/embassy-rs/embassy/pull/4824))
 
 ## 0.8.0 - 2025-08-26
 
diff --git a/embassy-rp/src/pio_programs/onewire.rs b/embassy-rp/src/pio_programs/onewire.rs
index 09babc229..3adab3b79 100644
--- a/embassy-rp/src/pio_programs/onewire.rs
+++ b/embassy-rp/src/pio_programs/onewire.rs
@@ -163,7 +163,11 @@ impl<'d, PIO: Instance, const SM: usize> PioOneWire<'d, PIO, SM> {
 
     /// Write bytes to the onewire bus
     pub async fn write_bytes(&mut self, data: &[u8]) {
-        unsafe { self.sm.set_y(u32::MAX as u32) };
+        unsafe {
+            self.sm.set_enable(false);
+            self.sm.set_y(u32::MAX as u32);
+            self.sm.set_enable(true);
+        }
         let (rx, tx) = self.sm.rx_tx();
         for b in data {
             tx.wait_push(*b as u32).await;
@@ -175,7 +179,11 @@ impl<'d, PIO: Instance, const SM: usize> PioOneWire<'d, PIO, SM> {
 
     /// Write bytes to the onewire bus, then apply a strong pullup
     pub async fn write_bytes_pullup(&mut self, data: &[u8], pullup_time: embassy_time::Duration) {
-        unsafe { self.sm.set_y(data.len() as u32 * 8 - 1) };
+        unsafe {
+            self.sm.set_enable(false);
+            self.sm.set_y(data.len() as u32 * 8 - 1);
+            self.sm.set_enable(true);
+        };
         let (rx, tx) = self.sm.rx_tx();
         for b in data {
             tx.wait_push(*b as u32).await;
@@ -195,7 +203,11 @@ impl<'d, PIO: Instance, const SM: usize> PioOneWire<'d, PIO, SM> {
 
     /// Read bytes from the onewire bus
     pub async fn read_bytes(&mut self, data: &mut [u8]) {
-        unsafe { self.sm.set_y(u32::MAX as u32) };
+        unsafe {
+            self.sm.set_enable(false);
+            self.sm.set_y(u32::MAX as u32);
+            self.sm.set_enable(true);
+        };
         let (rx, tx) = self.sm.rx_tx();
         for b in data {
             // Write all 1's so that we can read what the device responds