From a5c323cc1939dd3b2b8789c19f0c258ac2adb257 Mon Sep 17 00:00:00 2001
From: taco <taco@sly.nu>
Date: Wed, 29 Jul 2026 23:19:40 +1000
Subject: [PATCH] STM32WLx: add IRQ timeout logic

---
 src/helpers/radiolib/CustomSTM32WLx.h        | 58 +++++++++++++++++++-
 src/helpers/radiolib/CustomSTM32WLxWrapper.h |  3 +
 2 files changed, 58 insertions(+), 3 deletions(-)

diff --git a/src/helpers/radiolib/CustomSTM32WLx.h b/src/helpers/radiolib/CustomSTM32WLx.h
index 01190d06..e312a5ee 100644
--- a/src/helpers/radiolib/CustomSTM32WLx.h
+++ b/src/helpers/radiolib/CustomSTM32WLx.h
@@ -3,6 +3,11 @@
 #include <RadioLib.h>
 
 class CustomSTM32WLx : public STM32WLx {
+  uint32_t _preambleMillis = 66;
+  uint32_t _maxPayloadMillis = 3934;
+  uint32_t _activityAt = 0;
+  bool _headerSeen = false;
+
   public:
     CustomSTM32WLx(STM32WLx_Module *mod) : STM32WLx(mod) { }
 
@@ -12,8 +17,55 @@ class CustomSTM32WLx : public STM32WLx {
     }
 
     bool isReceiving() {
-      uint16_t irq = getIrqFlags();
-      bool detected = (irq & RADIOLIB_SX126X_IRQ_HEADER_VALID) || (irq & RADIOLIB_SX126X_IRQ_PREAMBLE_DETECTED);
-      return detected;
+      uint32_t irq = getIrqFlags();
+      bool preamble = irq & RADIOLIB_SX126X_IRQ_PREAMBLE_DETECTED; // bit 2
+      bool header   = irq & RADIOLIB_SX126X_IRQ_HEADER_VALID;      // bit 4
+      bool hdrErr   = irq & RADIOLIB_SX126X_IRQ_HEADER_ERR;        // bit 5
+      uint32_t now  = millis();
+      if (hdrErr) {
+        clearIrqFlags(RADIOLIB_SX126X_IRQ_PREAMBLE_DETECTED | RADIOLIB_SX126X_IRQ_HEADER_VALID | RADIOLIB_SX126X_IRQ_HEADER_ERR | RADIOLIB_SX126X_IRQ_SYNC_WORD_VALID);
+        _activityAt = 0;
+        _headerSeen = false;
+        return false;
+      }
+      if (!header && _headerSeen) {
+        // something cleared the header flag, reset our state.
+        _activityAt = 0; _headerSeen = false;
+        return false;
+      }
+
+      if (header) {
+        if (!_headerSeen) { _headerSeen = true; _activityAt = now; };
+        if (now - _activityAt > _maxPayloadMillis) {
+          MESH_DEBUG_PRINTLN("Clearing header IRQ after %ums", _maxPayloadMillis);
+          clearIrqFlags(RADIOLIB_SX126X_IRQ_PREAMBLE_DETECTED | RADIOLIB_SX126X_IRQ_HEADER_VALID | RADIOLIB_SX126X_IRQ_HEADER_ERR | RADIOLIB_SX126X_IRQ_SYNC_WORD_VALID);
+          _activityAt = 0; _headerSeen = false;
+          return false;
+        }
+        return true;
+      }
+      if (preamble) {
+        if (_activityAt == 0) _activityAt = now;
+        if (now - _activityAt > _preambleMillis) {
+          clearIrqFlags(RADIOLIB_SX126X_IRQ_PREAMBLE_DETECTED);
+          _activityAt = 0;
+          MESH_DEBUG_PRINTLN("Clearing preamble IRQ after %ums", _preambleMillis);
+
+          return false;
+        }
+        return true;
+      }
+      _activityAt = 0; _headerSeen = false;
+      return false;
     }
+
+    void setPreambleMillis(uint32_t preambleMillis) {
+      _preambleMillis = preambleMillis;
+      MESH_DEBUG_PRINTLN("Set _preambleMillis=%u", _preambleMillis);
+    }
+    void setMaxPayloadMillis(uint32_t payloadMillis) {
+      _maxPayloadMillis = payloadMillis;
+      MESH_DEBUG_PRINTLN("Set _maxPayloadMillis=%u", _maxPayloadMillis);
+    }
+
 };
\ No newline at end of file
diff --git a/src/helpers/radiolib/CustomSTM32WLxWrapper.h b/src/helpers/radiolib/CustomSTM32WLxWrapper.h
index 97bf6820..a792a877 100644
--- a/src/helpers/radiolib/CustomSTM32WLxWrapper.h
+++ b/src/helpers/radiolib/CustomSTM32WLxWrapper.h
@@ -15,6 +15,9 @@ public:
     ((CustomSTM32WLx *)_radio)->setBandwidth(bw);
     ((CustomSTM32WLx *)_radio)->setCodingRate(cr);
     updatePreamble(sf);
+    PacketMillis pm = calcMaxPacketMillis(sf, bw, cr, preambleLengthForSF(sf));
+    ((CustomSTM32WLx *)_radio)->setPreambleMillis(pm.preambleMillis);
+    ((CustomSTM32WLx *)_radio)->setMaxPayloadMillis(pm.payloadMillis);
   }
 
   bool isReceivingPacket() override {