From 84f1e11d29823d51a0047beb07d76b9523093ce5 Mon Sep 17 00:00:00 2001
From: Ev Lbibass <27320050+lbibass@users.noreply.github.com>
Date: Sun, 20 Sep 2026 20:38:05 -0400
Subject: [PATCH] update structure of LR1121 to match LR1110 files. Implement
 DC-DC on LR1121 radio. saves about 30% power consumption at idle.

---
 src/helpers/radiolib/CustomLR1121.h        | 72 ++++++++++++++++++++--
 src/helpers/radiolib/CustomLR1121Wrapper.h |  3 +
 2 files changed, 71 insertions(+), 4 deletions(-)

diff --git a/src/helpers/radiolib/CustomLR1121.h b/src/helpers/radiolib/CustomLR1121.h
index 873bfabc4e..67e3b52a97 100644
--- a/src/helpers/radiolib/CustomLR1121.h
+++ b/src/helpers/radiolib/CustomLR1121.h
@@ -4,11 +4,25 @@
 #include "MeshCore.h"
 
 class CustomLR1121 : public LR1121 {
+  uint32_t _preambleMillis = 66;
+  uint32_t _maxPayloadMillis = 3934;
+  uint32_t _activityAt = 0;
+  bool _headerSeen = false;
   bool _rx_boosted = false;
 
   public:
     CustomLR1121(Module *mod) : LR1121(mod) { }
 
+    int16_t begin(float freq = 434.0, float bw = 125.0, uint8_t sf = 9, uint8_t cr = 7,
+                  uint8_t syncWord = RADIOLIB_LR11X0_LORA_SYNC_WORD_PRIVATE, int8_t power = 10,
+                  uint16_t preambleLength = 8, float tcxoVoltage = 1.6) {
+      int16_t state = LR1121::begin(freq, bw, sf, cr, syncWord, power, preambleLength,
+                                    tcxoVoltage);
+      // RadioLib begin() defaults to LDO; use the LR1121 DC/DC regulator.
+      if (state == RADIOLIB_ERR_NONE) state = setRegulatorDCDC();
+      return state;
+    }
+
     size_t getPacketLength(bool update) override {
       size_t len = LR1121::getPacketLength(update);
       if (len == 0 && getIrqStatus() & RADIOLIB_LR11X0_IRQ_HEADER_ERR) {
@@ -31,11 +45,61 @@ class CustomLR1121 : public LR1121 {
 
     bool getRxBoostedGainMode() const { return _rx_boosted; }
 
+    int16_t startReceive() override {
+      // include the PREAMBLE_DETECTED irq bit in reported flags.
+      return LR1121::startReceive(RADIOLIB_LR11X0_RX_TIMEOUT_INF, RADIOLIB_IRQ_RX_DEFAULT_FLAGS | (1UL << RADIOLIB_IRQ_PREAMBLE_DETECTED), RADIOLIB_IRQ_RX_DEFAULT_MASK, 0);
+    }
+
     bool isReceiving() {
-      uint16_t irq = getIrqStatus();
-      bool detected = ((irq & RADIOLIB_LR11X0_IRQ_SYNC_WORD_HEADER_VALID) || (irq & RADIOLIB_LR11X0_IRQ_PREAMBLE_DETECTED));
-      return detected;
+      uint32_t irq = getIrqStatus();
+      bool preamble = irq & RADIOLIB_LR11X0_IRQ_PREAMBLE_DETECTED;      // bit 4
+      bool header   = irq & RADIOLIB_LR11X0_IRQ_SYNC_WORD_HEADER_VALID; // bit 5
+      bool hdrErr   = irq & RADIOLIB_LR11X0_IRQ_HEADER_ERR;             // bit 6
+      uint32_t now  = millis();
+      if (hdrErr) {
+        clearIrqState(RADIOLIB_LR11X0_IRQ_PREAMBLE_DETECTED | RADIOLIB_LR11X0_IRQ_SYNC_WORD_HEADER_VALID | RADIOLIB_LR11X0_IRQ_HEADER_ERR);
+        _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);
+          clearIrqState(RADIOLIB_LR11X0_IRQ_PREAMBLE_DETECTED | RADIOLIB_LR11X0_IRQ_SYNC_WORD_HEADER_VALID | RADIOLIB_LR11X0_IRQ_HEADER_ERR);
+          _activityAt = 0; _headerSeen = false;
+          return false;
+        }
+        return true;
+      }
+      if (preamble) {
+        if (_activityAt == 0) _activityAt = now;
+        if (now - _activityAt > _preambleMillis) {
+          clearIrqState(RADIOLIB_LR11X0_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);
     }
-    uint8_t getSpreadingFactor() const { return spreadingFactor; }
 
+    uint8_t getSpreadingFactor() const { return spreadingFactor; }
 };
\ No newline at end of file
diff --git a/src/helpers/radiolib/CustomLR1121Wrapper.h b/src/helpers/radiolib/CustomLR1121Wrapper.h
index 5361ee238d..5a754cee83 100644
--- a/src/helpers/radiolib/CustomLR1121Wrapper.h
+++ b/src/helpers/radiolib/CustomLR1121Wrapper.h
@@ -14,6 +14,9 @@ class CustomLR1121Wrapper : public RadioLibWrapper {
     ((CustomLR1121 *)_radio)->setBandwidth(bw);
     ((CustomLR1121 *)_radio)->setCodingRate(cr);
     updatePreamble(sf);
+    PacketMillis pm = calcMaxPacketMillis(sf, bw, cr, preambleLengthForSF(sf));
+    ((CustomLR1121 *)_radio)->setPreambleMillis(pm.preambleMillis);
+    ((CustomLR1121 *)_radio)->setMaxPayloadMillis(pm.payloadMillis);
   }
 
   void doResetAGC() override { lr11x0ResetAGC((LR11x0 *)_radio, ((CustomLR1121 *)_radio)->getFreqMHz(), getRxBoostedGainMode()); }