From 3d5adf8779d12fdf8c8372654002259e14b45b95 Mon Sep 17 00:00:00 2001
From: jgromes <jan.gromes@gmail.com>
Date: Sat, 6 Sep 2025 16:27:45 +0100
Subject: [PATCH] [SX126x] Implement blocking receive timeout

---
 src/modules/SX126x/SX126x.cpp | 63 ++++++++++++++++-------------------
 src/modules/SX126x/SX126x.h   |  8 +++--
 2 files changed, 34 insertions(+), 37 deletions(-)

diff --git a/src/modules/SX126x/SX126x.cpp b/src/modules/SX126x/SX126x.cpp
index 4d2f8555..922e9389 100644
--- a/src/modules/SX126x/SX126x.cpp
+++ b/src/modules/SX126x/SX126x.cpp
@@ -249,38 +249,37 @@ int16_t SX126x::transmit(const uint8_t* data, size_t len, uint8_t addr) {
   return(finishTransmit());
 }
 
-int16_t SX126x::receive(uint8_t* data, size_t len) {
+int16_t SX126x::receive(uint8_t* data, size_t len, RadioLibTime_t timeout) {
   // set mode to standby
   int16_t state = standby();
   RADIOLIB_ASSERT(state);
 
-  RadioLibTime_t timeout = 0;
+  RadioLibTime_t timeoutInternal = timeout;
+  if(!timeoutInternal) {
+    // get currently active modem
+    uint8_t modem = getPacketType();
+    if(modem == RADIOLIB_SX126X_PACKET_TYPE_LORA) {
+      // calculate timeout (100 LoRa symbols, the default for SX127x series)
+      float symbolLength = (float)(uint32_t(1) << this->spreadingFactor) / (float)this->bandwidthKhz;
+      timeoutInternal = (RadioLibTime_t)(symbolLength * 100.0f);
+    
+    } else if(modem == RADIOLIB_SX126X_PACKET_TYPE_GFSK) {
+      // calculate timeout (500 % of expected time-one-air)
+      size_t maxLen = len;
+      if(len == 0) { maxLen = 0xFF; }
+      float brBps = (RADIOLIB_SX126X_CRYSTAL_FREQ * 1000000.0f * 32.0f) / (float)this->bitRate;
+      timeoutInternal = (RadioLibTime_t)(((maxLen * 8.0f) / brBps) * 1000.0f * 5.0f);
 
-  // get currently active modem
-  uint8_t modem = getPacketType();
-  if(modem == RADIOLIB_SX126X_PACKET_TYPE_LORA) {
-    // calculate timeout (100 LoRa symbols, the default for SX127x series)
-    float symbolLength = (float)(uint32_t(1) << this->spreadingFactor) / (float)this->bandwidthKhz;
-    timeout = (RadioLibTime_t)(symbolLength * 100.0f);
-  
-  } else if(modem == RADIOLIB_SX126X_PACKET_TYPE_GFSK) {
-    // calculate timeout (500 % of expected time-one-air)
-    size_t maxLen = len;
-    if(len == 0) {
-      maxLen = 0xFF;
+    } else {
+      return(RADIOLIB_ERR_UNKNOWN);
+    
     }
-    float brBps = (RADIOLIB_SX126X_CRYSTAL_FREQ * 1000000.0f * 32.0f) / (float)this->bitRate;
-    timeout = (RadioLibTime_t)(((maxLen * 8.0f) / brBps) * 1000.0f * 5.0f);
-
-  } else {
-    return(RADIOLIB_ERR_UNKNOWN);
-  
   }
 
-  RADIOLIB_DEBUG_BASIC_PRINTLN("Timeout in %lu ms", timeout);
+  RADIOLIB_DEBUG_BASIC_PRINTLN("Timeout in %lu ms", timeoutInternal);
 
   // start reception
-  uint32_t timeoutValue = (uint32_t)(((float)timeout * 1000.0f) / 15.625f);
+  uint32_t timeoutValue = (uint32_t)(((float)timeoutInternal * 1000.0f) / 15.625f);
   state = startReceive(timeoutValue);
   RADIOLIB_ASSERT(state);
 
@@ -290,7 +289,7 @@ int16_t SX126x::receive(uint8_t* data, size_t len) {
   while(!this->mod->hal->digitalRead(this->mod->getIrq())) {
     this->mod->hal->yield();
     // safety check, the timeout should be done by the radio
-    if(this->mod->hal->millis() - start > timeout) {
+    if(this->mod->hal->millis() - start > timeoutInternal) {
       softTimeout = true;
       break;
     }
@@ -302,18 +301,14 @@ int16_t SX126x::receive(uint8_t* data, size_t len) {
     return(state);
   }
 
-  // check whether this was a timeout or not
-  if((getIrqFlags() & RADIOLIB_SX126X_IRQ_TIMEOUT) || softTimeout) {
-    standby();
-    fixImplicitTimeout();
-    clearIrqStatus();
-    return(RADIOLIB_ERR_RX_TIMEOUT);
-  }
+  // cache the IRQ flags and clean up after reception
+  uint32_t irqFlags = getIrqFlags();
+  state = finishReceive();
+  RADIOLIB_ASSERT(state);
 
-  // fix timeout in implicit LoRa mode
-  if(((this->headerType == RADIOLIB_SX126X_LORA_HEADER_IMPLICIT) && (getPacketType() == RADIOLIB_SX126X_PACKET_TYPE_LORA))) {
-    state = fixImplicitTimeout();
-    RADIOLIB_ASSERT(state);
+  // check whether this was a timeout or not
+  if((irqFlags & RADIOLIB_SX126X_IRQ_TIMEOUT) || softTimeout) {
+    return(RADIOLIB_ERR_RX_TIMEOUT);
   }
 
   // read the received data
diff --git a/src/modules/SX126x/SX126x.h b/src/modules/SX126x/SX126x.h
index aa262009..28173994 100644
--- a/src/modules/SX126x/SX126x.h
+++ b/src/modules/SX126x/SX126x.h
@@ -567,11 +567,13 @@ class SX126x: public PhysicalLayer {
     /*!
       \brief Blocking binary receive method.
       Overloads for string-based transmissions are implemented in PhysicalLayer.
-      \param data Binary data to be sent.
-      \param len Number of bytes to send.
+      \param data Pointer to array to save the received binary data.
+      \param len Number of bytes that will be received. Must be known in advance for binary transmissions.
+      \param timeout Reception timeout in milliseconds. If set to 0,
+      timeout period will be calculated automatically based on the radio configuration.
       \returns \ref status_codes
     */
-    int16_t receive(uint8_t* data, size_t len) override;
+    int16_t receive(uint8_t* data, size_t len, RadioLibTime_t timeout = 0) override;
 
     /*!
       \brief Starts direct mode transmission.