[SX126x] Changed CAD to only use DIO1 (#19)

examples/SX126x/SX126x_Channel_Activity_Detection/SX126x_Channel_Activity_Detection.ino

@@ -65,10 +65,10 @@ void loop() {
     // no preamble was detected, channel is free
     Serial.println(F("channel is free!"));
 
-  } else if (state == ERR_CAD_UNAVAILABLE) {
-    // no preamble was detected, channel is free
-    Serial.println(F("unable to perform scan!"));
-    Serial.println(F("[SX1262] Disable DIO2 RF control to run CAD."));
+  } else {
+    // some other error occurred
+    Serial.print(F("failed, code "));
+    Serial.println(state);
 
   }
 

examples/SX126x/SX126x_Settings/SX126x_Settings.ino

@@ -150,7 +150,7 @@ void setup() {
   // Some SX126x modules use DIO2 as RF switch. To enable
   // this feature, the following method can be used.
   // NOTE: As long as DIO2 is configured to control RF switch,
-  //       Channel Activity Detection is disabled!
+  //       it can't be used as interrupt pin!
   if (loraSX1262.setDio2AsRfSwitch() != ERR_NONE) {
     Serial.println(F("Failed to set DIO2 as RF switch!"));
     while (true);

keywords.txt

@@ -232,4 +232,3 @@ ERR_INVALID_MODULATION_PARAMETERS	LITERAL1
 ERR_SPI_CMD_TIMEOUT	LITERAL1
 ERR_SPI_CMD_INVALID	LITERAL1
 ERR_SPI_CMD_FAILED	LITERAL1
-ERR_CAD_UNAVAILABLE	LITERAL1

src/TypeDef.h

@@ -461,11 +461,6 @@
 */
 #define ERR_SPI_CMD_FAILED                    -707
 
-/*!
-  \brief SX126x scan channel not possible because DIO2 is used as RF antenna switch.
-*/
-#define ERR_CAD_UNAVAILABLE                  -708
-
 /*!
   \}
 */

src/modules/SX126x.cpp

@@ -285,11 +285,6 @@ int16_t SX126x::scanChannel() {
     return(ERR_WRONG_MODEM);
   }
 
-  if (_dio2RfSwitch) {
-    // If DIO2 is used as RF switch this function does not work
-    return(ERR_CAD_UNAVAILABLE);
-  }
-
   // set mode to standby
   int16_t state = standby();
   if(state != ERR_NONE) {
@@ -297,7 +292,7 @@ int16_t SX126x::scanChannel() {
   }
 
   // set DIO pin mapping
-  state = setDioIrqParams(SX126X_IRQ_CAD_DETECTED | SX126X_IRQ_CAD_DONE, SX126X_IRQ_CAD_DONE, SX126X_IRQ_CAD_DETECTED);
+  state = setDioIrqParams(SX126X_IRQ_CAD_DETECTED | SX126X_IRQ_CAD_DONE, SX126X_IRQ_CAD_DETECTED | SX126X_IRQ_CAD_DONE);
   if(state != ERR_NONE) {
     return(state);
   }
@@ -315,19 +310,23 @@ int16_t SX126x::scanChannel() {
   }
 
   // wait for channel activity detected or timeout
-  while(!digitalRead(_mod->getInt0())) {
-    if(digitalRead(_mod->getInt1())) {
+  while(!digitalRead(_mod->getInt0()));
+
+  // check CAD result
+  uint16_t cadResult = getIrqStatus();
+  if(cadResult & SX126X_IRQ_CAD_DETECTED) {
+    // detected some LoRa activity
     clearIrqStatus();
     return(LORA_DETECTED);
-    }
-  }
-
-  // clear interrupt flags
+  } else if(cadResult & SX126X_IRQ_CAD_DONE) {
+    // channel is free
     clearIrqStatus();
-
     return(CHANNEL_FREE);
   }
 
+  return(ERR_UNKNOWN);
+}
+
 int16_t SX126x::sleep() {
   uint8_t data[] = {SX126X_SLEEP_START_COLD | SX126X_SLEEP_RTC_OFF};
   int16_t state = SPIwriteCommand(SX126X_CMD_SET_SLEEP, data, 1);
@@ -911,6 +910,16 @@ int16_t SX126x::setTCXO(float voltage, uint32_t timeout) {
   return(ERR_NONE);
 }
 
+int16_t SX126x::setDio2AsRfSwitch(bool enable) {
+  uint8_t data = 0;
+  if(enable) {
+    data = SX126X_DIO2_AS_RF_SWITCH;
+  } else {
+    data = SX126X_DIO2_AS_IRQ;
+  }
+  return(SPIwriteCommand(SX126X_CMD_SET_DIO2_AS_RF_SWITCH_CTRL, &data, 1));
+}
+
 int16_t SX126x::setTx(uint32_t timeout) {
   uint8_t data[3] = {(uint8_t)((timeout >> 16) & 0xFF), (uint8_t)((timeout >> 8) & 0xFF), (uint8_t)(timeout & 0xFF)};
   return(SPIwriteCommand(SX126X_CMD_SET_TX, data, 3));
@@ -971,7 +980,7 @@ int16_t SX126x::setDioIrqParams(uint16_t irqMask, uint16_t dio1Mask, uint16_t di
 uint16_t SX126x::getIrqStatus() {
   uint8_t data[2];
   SPIreadCommand(SX126X_CMD_GET_IRQ_STATUS, data, 2);
-  return(((uint16_t)(data[1]) << 8) | data[0]);
+  return(((uint16_t)(data[0]) << 8) | data[1]);
 }
 
 int16_t SX126x::clearIrqStatus(uint16_t clearIrqParams) {
@@ -1074,21 +1083,6 @@ int16_t SX126x::setFrequencyRaw(float freq) {
   return(ERR_NONE);
 }
 
-int16_t SX126x::setDio2AsRfSwitch(bool enable) {
-  uint8_t data = 0;
-  if(enable) {
-    data = SX126X_DIO2_AS_RF_SWITCH;
-  } else {
-    data = SX126X_DIO2_AS_IRQ;
-  }
-  int16_t state = SPIwriteCommand(SX126X_CMD_SET_DIO2_AS_RF_SWITCH_CTRL, &data, 1);
-
-  if(state == ERR_NONE) {
-    _dio2RfSwitch = enable;
-  }
-  return(state);
-}
-
 int16_t SX126x::config(uint8_t modem) {
   // set regulator mode
   uint8_t* data = new uint8_t[1];

src/modules/SX126x.h

@@ -657,6 +657,13 @@ class SX126x: public PhysicalLayer {
     */
     int16_t setTCXO(float voltage, uint32_t timeout = 5000);
 
+    /*!
+      \brief Set DIO2 to function as RF switch (default in Semtech example designs).
+
+      \returns \ref status_codes
+    */
+    int16_t setDio2AsRfSwitch(bool enable = true);
+
     /*!
       \brief Gets effective data rate for the last transmitted packet. The value is calculated only for payload bytes.
 
@@ -678,13 +685,6 @@ class SX126x: public PhysicalLayer {
     */
     float getSNR();
 
-    /*!
-      \brief Set DIO2 to function as RF switch (default in Semtech example designs).
-
-      \returns \ref status_codes 
-    */
-    int16_t setDio2AsRfSwitch(bool enable = true);
-
   protected:
     // SX1276x SPI command implementations
     int16_t setTx(uint32_t timeout = 0);
@@ -727,8 +727,6 @@ class SX126x: public PhysicalLayer {
 
     float _dataRate;
 
-    bool _dio2RfSwitch = false;
-
     int16_t config(uint8_t modem);
 
     // common low-level SPI interface