From 9d4f93806d83abd593bbaae51c2944cac12c422b Mon Sep 17 00:00:00 2001
From: taco <taco@sly.nu>
Date: Sun, 12 Jul 2026 18:03:25 +1000
Subject: [PATCH] LR2021: auto-LDRO for side detectors

---
 examples/simple_repeater/MyMesh.cpp        |  4 ++--
 examples/simple_repeater/MyMesh.h          |  2 +-
 src/helpers/CommonCLI.cpp                  |  2 +-
 src/helpers/CommonCLI.h                    |  2 +-
 src/helpers/radiolib/CustomLR2021Wrapper.h | 11 ++++++++---
 src/helpers/radiolib/RadioLibWrappers.h    |  2 +-
 6 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/examples/simple_repeater/MyMesh.cpp b/examples/simple_repeater/MyMesh.cpp
index cc0cc1f1a..6da8cca2c 100644
--- a/examples/simple_repeater/MyMesh.cpp
+++ b/examples/simple_repeater/MyMesh.cpp
@@ -1065,8 +1065,8 @@ bool MyMesh::setRxBoostedGain(bool enable) {
 }
 
 #if defined(USE_LR2021)
-bool MyMesh::configSideDetectors(const uint8_t sideDetSFs[], uint8_t num) {
-  return radio_driver.configSideDetectors(sideDetSFs, num);
+bool MyMesh::configSideDetectors(const uint8_t sideDetSFs[], uint8_t num, float bw) {
+  return radio_driver.configSideDetectors(sideDetSFs, num, bw);
 }
 #endif
 
diff --git a/examples/simple_repeater/MyMesh.h b/examples/simple_repeater/MyMesh.h
index 6a260e339..ff35cfab2 100644
--- a/examples/simple_repeater/MyMesh.h
+++ b/examples/simple_repeater/MyMesh.h
@@ -256,7 +256,7 @@ public:
   bool setRxBoostedGain(bool enable) override;
 
   #if defined(USE_LR2021)
-  virtual bool configSideDetectors(const uint8_t sideDetSFs[], uint8_t num) override;
+  virtual bool configSideDetectors(const uint8_t sideDetSFs[], uint8_t num, float bw) override;
   #endif
 
 };
diff --git a/src/helpers/CommonCLI.cpp b/src/helpers/CommonCLI.cpp
index bb54197f5..07181e16a 100644
--- a/src/helpers/CommonCLI.cpp
+++ b/src/helpers/CommonCLI.cpp
@@ -766,7 +766,7 @@ void CommonCLI::handleSetCmd(uint32_t sender_timestamp, char* command, char* rep
         sideDetSFs[i] = atoi(parts[i]);
       }
       sideDetSFs[num] = 0;
-      if (_callbacks->configSideDetectors(sideDetSFs, num)) {
+      if (_callbacks->configSideDetectors(sideDetSFs, num, _prefs->bw)) {
         for (int i = 0; i <= num; i++) _prefs->extra_sf[i] = sideDetSFs[i];
         savePrefs();
         sprintf(reply, "OK - extra SFs set");
diff --git a/src/helpers/CommonCLI.h b/src/helpers/CommonCLI.h
index fafabcb17..2a9ec43bc 100644
--- a/src/helpers/CommonCLI.h
+++ b/src/helpers/CommonCLI.h
@@ -241,7 +241,7 @@ public:
   };
 
   #if defined(USE_LR2021)
-  virtual bool configSideDetectors(const uint8_t sideDetSFs[], uint8_t num) {
+  virtual bool configSideDetectors(const uint8_t sideDetSFs[], uint8_t num, float bw) {
     return false; // Override in wrapper
   } 
   #endif
diff --git a/src/helpers/radiolib/CustomLR2021Wrapper.h b/src/helpers/radiolib/CustomLR2021Wrapper.h
index 6d0204ac1..879898315 100644
--- a/src/helpers/radiolib/CustomLR2021Wrapper.h
+++ b/src/helpers/radiolib/CustomLR2021Wrapper.h
@@ -24,7 +24,7 @@ public:
     applySideDetectorConfig();
   }
 
-  bool configSideDetectors(const uint8_t* sideDetSFs, uint8_t num) override {
+  bool configSideDetectors(const uint8_t* sideDetSFs, uint8_t num, float bw) override {
     LR2021LoRaSideDetector_t tmp[3];
     uint8_t sf = getSpreadingFactor();
 
@@ -35,7 +35,8 @@ public:
       if (sideDetSFs[i] > sf + 4) { return false; }  // span must not be > 4
 
       tmp[i].sf = sideDetSFs[i];
-      if (sideDetSFs[i] == 10) { // TODO: set ldro=true when tSym >=16
+      float tSym = calcTsym(tmp[i].sf, bw);
+      if (tSym >= 16.0f) {
         tmp[i].ldro = true;
       } else {
         tmp[i].ldro = false; 
@@ -63,6 +64,11 @@ public:
     return status;
   }
 
+  float calcTsym(uint8_t sf, float bw) {
+    float tSym = (float)(uint32_t(1) << sf) / (float)bw;
+    return tSym;
+  }
+
   bool isReceivingPacket() override {
     return ((CustomLR2021 *)_radio)->isReceiving();
   }
@@ -98,5 +104,4 @@ public:
     LR2021LoRaSideDetector_t _sideDet[3];
     size_t _numSideDet = 0;
 
-
 };
diff --git a/src/helpers/radiolib/RadioLibWrappers.h b/src/helpers/radiolib/RadioLibWrappers.h
index 4ca958e47..99f5ebbd8 100644
--- a/src/helpers/radiolib/RadioLibWrappers.h
+++ b/src/helpers/radiolib/RadioLibWrappers.h
@@ -78,7 +78,7 @@ public:
   virtual bool setRxBoostedGainMode(bool) { return false; }
   virtual bool getRxBoostedGainMode() const { return false; }
   
-  virtual bool configSideDetectors(const uint8_t sideDetSFs[], uint8_t num) { return false; }
+  virtual bool configSideDetectors(const uint8_t sideDetSFs[], uint8_t num, float bw) { return false; }
 };
 
 /**