From a436beb9d14949d85fe091c69a509dbaae5a56e2 Mon Sep 17 00:00:00 2001
From: pelgraine <140762863+pelgraine@users.noreply.github.com>
Date: Thu, 16 Jul 2026 19:00:38 +1000
Subject: [PATCH] T-Watch S3: fixed tilt raise bug.

Applied the same memw barrier + identical comment to twatchs3plusboard.cpp, hardening the Plus against the same latent race it was previously surviving only by luck
---
 variants/lilygo_twatch_s3/TWatchS3Board.cpp          | 5 ++++-
 variants/lilygo_twatch_s3/TWatchS3Board.h            | 2 +-
 variants/lilygo_twatch_s3_plus/TWatchS3PlusBoard.cpp | 5 ++++-
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/variants/lilygo_twatch_s3/TWatchS3Board.cpp b/variants/lilygo_twatch_s3/TWatchS3Board.cpp
index 82b0647d..68194965 100644
--- a/variants/lilygo_twatch_s3/TWatchS3Board.cpp
+++ b/variants/lilygo_twatch_s3/TWatchS3Board.cpp
@@ -5,7 +5,10 @@
 
 volatile bool TWatchS3Board::_tilt_flag = false;
 
-void IRAM_ATTR TWatchS3Board::onTiltISR() { _tilt_flag = true; }
+// memw forces the _tilt_flag store to retire to SRAM before this ISR
+// returns. Without it, tiltFired() in the main loop can read a stale
+// value and raise-to-wake is missed. Do not remove.
+void IRAM_ATTR TWatchS3Board::onTiltISR() { _tilt_flag = true; asm volatile("memw" ::: "memory"); }
 
 // ---- Wrapper-free BMA423 step counter (raw I2C) ----------------------------
 // SensorLib's SensorBMA423 step-counter methods do not compile in this build,
diff --git a/variants/lilygo_twatch_s3/TWatchS3Board.h b/variants/lilygo_twatch_s3/TWatchS3Board.h
index 63d55818..fd654cfd 100644
--- a/variants/lilygo_twatch_s3/TWatchS3Board.h
+++ b/variants/lilygo_twatch_s3/TWatchS3Board.h
@@ -80,4 +80,4 @@ public:
   const char* getManufacturerName() const override {
     return "LilyGo T-Watch S3";
   }
-};
+};
\ No newline at end of file
diff --git a/variants/lilygo_twatch_s3_plus/TWatchS3PlusBoard.cpp b/variants/lilygo_twatch_s3_plus/TWatchS3PlusBoard.cpp
index b4c0fe45..92139bbe 100644
--- a/variants/lilygo_twatch_s3_plus/TWatchS3PlusBoard.cpp
+++ b/variants/lilygo_twatch_s3_plus/TWatchS3PlusBoard.cpp
@@ -5,7 +5,10 @@
 
 volatile bool TWatchS3PlusBoard::_tilt_flag = false;
 
-void IRAM_ATTR TWatchS3PlusBoard::onTiltISR() { _tilt_flag = true; }
+// memw forces the _tilt_flag store to retire to SRAM before this ISR
+// returns. Without it, tiltFired() in the main loop can read a stale
+// value and raise-to-wake is missed. Do not remove.
+void IRAM_ATTR TWatchS3PlusBoard::onTiltISR() { _tilt_flag = true; asm volatile("memw" ::: "memory"); }
 
 // ---- Wrapper-free BMA423 step counter (raw I2C) ----------------------------
 // SensorLib's SensorBMA423 step-counter methods do not compile in this build,