LLCC68: add IRQ timeout logic

src/helpers/radiolib/CustomLLCC68.h

@@ -3,6 +3,11 @@
 #include <RadioLib.h>
 
 class CustomLLCC68 : public LLCC68 {
+  uint32_t _preambleMillis = 66;
+  uint32_t _maxPayloadMillis = 3934;
+  uint32_t _activityAt = 0;
+  bool _headerSeen = false;
+
   public:
     CustomLLCC68(Module *mod) : LLCC68(mod) { }
 
@@ -81,9 +86,55 @@ class CustomLLCC68 : public LLCC68 {
     }
 
     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);
     }
 
     bool getRxBoostedGainMode() {

src/helpers/radiolib/CustomLLCC68Wrapper.h

@@ -14,6 +14,10 @@ public:
     ((CustomLLCC68 *)_radio)->setBandwidth(bw);
     ((CustomLLCC68 *)_radio)->setCodingRate(cr);
     updatePreamble(sf);
+    PacketMillis pm = calcMaxPacketMillis(sf, bw, cr, preambleLengthForSF(sf));
+    ((CustomLLCC68 *)_radio)->setPreambleMillis(pm.preambleMillis);
+    ((CustomLLCC68 *)_radio)->setMaxPayloadMillis(pm.payloadMillis);
+
   }
 
   bool isReceivingPacket() override {