[SX126x] Added interrupt-driven CAD

examples/SX126x/SX126x_Channel_Activity_Detection_Interrupt/SX126x_Channel_Activity_Detection_Interrupt.ino

@@ -0,0 +1,123 @@
+/*
+   RadioLib SX126x Channel Activity Detection Example
+
+   This example uses SX1262 to scan the current LoRa
+   channel and detect ongoing LoRa transmissions.
+   Unlike SX127x CAD, SX126x can detect any part
+   of LoRa transmission, not just the preamble.
+
+   Other modules from SX126x family can also be used.
+
+   For default module settings, see the wiki page
+   https://github.com/jgromes/RadioLib/wiki/Default-configuration#sx126x---lora-modem
+
+   For full API reference, see the GitHub Pages
+   https://jgromes.github.io/RadioLib/
+*/
+
+// include the library
+#include <RadioLib.h>
+
+// SX1262 has the following connections:
+// NSS pin:   10
+// DIO1 pin:  2
+// NRST pin:  3
+// BUSY pin:  9
+SX1262 radio = new Module(10, 2, 3, 9);
+
+// or using RadioShield
+// https://github.com/jgromes/RadioShield
+//SX1262 radio = RadioShield.ModuleA;
+
+void setup() {
+  Serial.begin(9600);
+
+  // initialize SX1262 with default settings
+  Serial.print(F("[SX1262] Initializing ... "));
+  int state = radio.begin();
+  if (state == ERR_NONE) {
+    Serial.println(F("success!"));
+  } else {
+    Serial.print(F("failed, code "));
+    Serial.println(state);
+    while (true);
+  }
+
+  // set the function that will be called
+  // when LoRa packet or timeout is detected
+  radio.setDio1Action(setFlag);
+
+  // start scanning the channel
+  Serial.print(F("[SX1262] Starting scan for LoRa preamble ... "));
+  state = radio.startChannelScan();
+  if (state == ERR_NONE) {
+    Serial.println(F("success!"));
+  } else {
+    Serial.print(F("failed, code "));
+    Serial.println(state);
+  }
+}
+
+// flag to indicate that a packet was detected or CAD timed out
+volatile bool scanFlag = false;
+
+// disable interrupt when it's not needed
+volatile bool enableInterrupt = true;
+
+// this function is called when a complete packet
+// is received by the module
+// IMPORTANT: this function MUST be 'void' type
+//            and MUST NOT have any arguments!
+void setFlag(void) {
+  // check if the interrupt is enabled
+  if(!enableInterrupt) {
+    return;
+  }
+
+  // something happened, set the flag
+  scanFlag = true;
+}
+
+void loop() {
+  // check if the flag is set
+  if(scanFlag) {
+    // disable the interrupt service routine while
+    // processing the data
+    enableInterrupt = false;
+
+    // reset flag
+    scanFlag = false;
+
+    // check CAD result
+    int state = radio.getChannelScanResult();
+
+    if (state == LORA_DETECTED) {
+      // LoRa packet was detected
+      Serial.println(F("[SX1262] Packet detected!"));
+
+    } else if (state == CHANNEL_FREE) {
+      // channel is free
+      Serial.println(F("[SX1262] Channel is free!"));
+
+    } else {
+      // some other error occurred
+      Serial.print(F("[SX1262] Failed, code "));
+      Serial.println(state);
+
+    }
+
+    // start scanning the channel again
+    Serial.print(F("[SX1262] Starting scan for LoRa preamble ... "));
+    state = radio.startChannelScan();
+    if (state == ERR_NONE) {
+      Serial.println(F("success!"));
+    } else {
+      Serial.print(F("failed, code "));
+      Serial.println(state);
+    }
+
+    // enable interrupt service routine
+    enableInterrupt = true;
+  }
+
+}

src/modules/SX126x/SX126x.cpp

@@ -331,28 +331,8 @@ int16_t SX126x::receiveDirect() {
 }
 
 int16_t SX126x::scanChannel() {
-  // check active modem
-  if(getPacketType() != SX126X_PACKET_TYPE_LORA) {
-    return(ERR_WRONG_MODEM);
-  }
-
-  // set mode to standby
-  int16_t state = standby();
-  RADIOLIB_ASSERT(state);
-
-  // set RF switch (if present)
-  _mod->setRfSwitchState(HIGH, LOW);
-
-  // set DIO pin mapping
-  state = setDioIrqParams(SX126X_IRQ_CAD_DETECTED | SX126X_IRQ_CAD_DONE, SX126X_IRQ_CAD_DETECTED | SX126X_IRQ_CAD_DONE);
-  RADIOLIB_ASSERT(state);
-
-  // clear interrupt flags
-  state = clearIrqStatus();
-  RADIOLIB_ASSERT(state);
-
   // set mode to CAD
-  state = setCad();
+  int state = startChannelScan();
   RADIOLIB_ASSERT(state);
 
   // wait for channel activity detected or timeout
@@ -361,18 +341,7 @@ int16_t SX126x::scanChannel() {
   }
 
   // check CAD result
-  uint16_t cadResult = getIrqStatus();
+  return(getChannelScanResult());
-  if(cadResult & SX126X_IRQ_CAD_DETECTED) {
-    // detected some LoRa activity
-    clearIrqStatus();
-    return(LORA_DETECTED);
-  } else if(cadResult & SX126X_IRQ_CAD_DONE) {
-    // channel is free
-    clearIrqStatus();
-    return(CHANNEL_FREE);
-  }
-
-  return(ERR_UNKNOWN);
 }
 
 int16_t SX126x::sleep(bool retainConfig) {
@@ -608,6 +577,53 @@ int16_t SX126x::readData(uint8_t* data, size_t len) {
   return(state);
 }
 
+int16_t SX126x::startChannelScan() {
+  // check active modem
+  if(getPacketType() != SX126X_PACKET_TYPE_LORA) {
+    return(ERR_WRONG_MODEM);
+  }
+
+  // set mode to standby
+  int16_t state = standby();
+  RADIOLIB_ASSERT(state);
+
+  // set RF switch (if present)
+  _mod->setRfSwitchState(HIGH, LOW);
+
+  // set DIO pin mapping
+  state = setDioIrqParams(SX126X_IRQ_CAD_DETECTED | SX126X_IRQ_CAD_DONE, SX126X_IRQ_CAD_DETECTED | SX126X_IRQ_CAD_DONE);
+  RADIOLIB_ASSERT(state);
+
+  // clear interrupt flags
+  state = clearIrqStatus();
+  RADIOLIB_ASSERT(state);
+
+  // set mode to CAD
+  state = setCad();
+  return(state);
+}
+
+int16_t SX126x::getChannelScanResult() {
+  // check active modem
+  if(getPacketType() != SX126X_PACKET_TYPE_LORA) {
+    return(ERR_WRONG_MODEM);
+  }
+
+  // check CAD result
+  uint16_t cadResult = getIrqStatus();
+  if(cadResult & SX126X_IRQ_CAD_DETECTED) {
+    // detected some LoRa activity
+    clearIrqStatus();
+    return(LORA_DETECTED);
+  } else if(cadResult & SX126X_IRQ_CAD_DONE) {
+    // channel is free
+    clearIrqStatus();
+    return(CHANNEL_FREE);
+  }
+
+  return(ERR_UNKNOWN);
+}
+
 int16_t SX126x::setBandwidth(float bw) {
   // check active modem
   if(getPacketType() != SX126X_PACKET_TYPE_LORA) {

src/modules/SX126x/SX126x.h

@@ -554,6 +554,20 @@ class SX126x: public PhysicalLayer {
     */
     int16_t readData(uint8_t* data, size_t len) override;
 
+    /*!
+      \brief Interrupt-driven channel activity detection method. DIO0 will be activated when LoRa preamble is detected, or upon timeout.
+
+      \returns \ref status_codes
+    */
+    int16_t startChannelScan();
+
+    /*!
+      \brief Read the channel scan result
+
+      \returns \ref status_codes
+    */
+    int16_t getChannelScanResult();
+
     // configuration methods
 
     /*!