cad test 3

README.md

@@ -51,6 +51,7 @@ ____________________________________________________
 <br />
 
 # Timeline (Versions):
+- 2026-06-10 CAD (Channel Activity Detection) and DIFS (Distributed Inter-Frame Space) added.
 - 2026-03-25 More Boards, SDK update, OTA fix, GPS process update.
 - 2026-02-26 9M2IBR ESP32 1W (400M30S) + GPS board added.
 - 2026-02-25 Code Improvements: reduced String comparisons and improved logic for faster code execution.

data/igate_conf.json

@@ -28,9 +28,9 @@
         "messagesToRF": false,
         "objectsToRF": false,
         "server": "rotate.aprs2.net",
-        "passcode": "XYZVW",        
+        "passcode": "XYZVW",
         "port": 14580,
-        "filter": "m/10"        
+        "filter": "m/10"
     },
     "personalNote": "",
     "blacklist": "",
@@ -40,6 +40,7 @@
         "backupDigiMode": false
     },
     "lora": {
+        "cadActive": true,
         "rxActive": true,
         "rxFreq": 433775000,
         "rxSpreadingFactor": 12,

include/configuration.h

@@ -75,6 +75,7 @@ public:
 
 class LoraModule {
 public:
+    bool    cadActive;
     bool    rxActive;
     long    rxFreq;
     int     rxSpreadingFactor;

src/LoRa_APRS_iGate.cpp

@@ -68,8 +68,8 @@ ___________________________________________________________________*/
 #endif
 
 
-String              versionDate             = "2026-04-21";
-String              versionNumber           = "3.2.4";
+String              versionDate             = "2026-06-10";
+String              versionNumber           = "3.3.0";
 Configuration       Config;
 WiFiClient          aprsIsClient;
 WiFiClient          mqttClient;

src/aprs_is_utils.cpp

@@ -16,7 +16,7 @@
  * along with LoRa APRS iGate. If not, see <https://www.gnu.org/licenses/>.
  */
 
-#include <APRSPacketLib.h> 
+#include <APRSPacketLib.h>
 #include <WiFiClient.h>
 #include "configuration.h"
 #include "network_manager.h"
@@ -47,7 +47,6 @@ extern bool                 modemLoggedToAPRSIS;
 extern bool                 backupDigiMode;
 extern String               versionNumber;
 
-uint32_t    lastRxTime      = millis();
 bool        passcodeValid   = false;
 uint32_t    lastServerCheck = 0;
 
@@ -403,7 +402,6 @@ namespace APRS_IS_Utils {
                     String aprsisPacket = aprsIsClient.readStringUntil('\r');
                     aprsisPacket.trim();    // Serial.println(aprsisPacket);
                     processAPRSISPacket(aprsisPacket);
-                    lastRxTime = millis();
                 }
             }
         #endif

src/configuration.cpp

@@ -97,6 +97,7 @@ bool Configuration::writeFile() {
         #endif
         data["digi"]["backupDigiMode"]              = digi.backupDigiMode;
 
+        data["lora"]["cadActive"]                   = loramodule.cadActive;
         data["lora"]["rxActive"]                    = loramodule.rxActive;
         data["lora"]["rxFreq"]                      = loramodule.rxFreq;
         data["lora"]["rxCodingRate4"]               = loramodule.rxCodingRate4;
@@ -291,7 +292,8 @@ bool Configuration::readFile() {
         digi.backupDigiMode             = data["digi"]["backupDigiMode"] | false;
 
 
-        if (data["lora"]["rxActive"].isNull() ||
+        if (data["lora"]["cadActive"].isNull() ||
+            data["lora"]["rxActive"].isNull() ||
             data["lora"]["rxFreq"].isNull() ||
             data["lora"]["rxSpreadingFactor"].isNull() ||
             data["lora"]["rxCodingRate4"].isNull() ||
@@ -302,6 +304,7 @@ bool Configuration::readFile() {
             data["lora"]["txCodingRate4"].isNull() ||
             data["lora"]["txSignalBandwidth"].isNull() ||
             data["lora"]["power"].isNull()) needsRewrite = true;
+        loramodule.cadActive            = data["lora"]["cadActive"] | true;
         loramodule.rxActive             = data["lora"]["rxActive"] | true;
         loramodule.rxFreq               = data["lora"]["rxFreq"] | 433775000;
         loramodule.rxSpreadingFactor    = data["lora"]["rxSpreadingFactor"] | 12;
@@ -492,6 +495,7 @@ void Configuration::setDefaultValues() {
     digi.ecoMode                    = 0;
     digi.backupDigiMode             = false;
 
+    loramodule.cadActive            = true;
     loramodule.rxActive             = true;
     loramodule.rxFreq               = 433775000;
     loramodule.rxSpreadingFactor    = 12;

src/lora_utils.cpp

@@ -28,15 +28,19 @@
 #include "utils.h"
 
 
+
+
 extern Configuration    Config;
 extern NetworkManager   *networkManager;
-extern uint32_t         lastRxTime;
 extern bool             packetIsBeacon;
 
 extern std::vector<ReceivedPacket> receivedPackets;
 
-bool operationDone   = true;
-bool transmitFlag    = true;
+bool operationDone      = true;
+bool transmitFlag       = true;
+
+#define DIFS_SLOTS      2       // Number of secuential CAD slots to consider a free channel to Tx
+int  backoffMax         = 4;    // Max Backoff value (number of CAD slots to wait before Tx)
 
 #ifdef HAS_SX1262
     SX1262 radio = new Module(RADIO_CS_PIN, RADIO_DIO1_PIN, RADIO_RST_PIN, RADIO_BUSY_PIN);
@@ -167,6 +171,34 @@ namespace LoRa_Utils {
         radio.setBandwidth(signalBandwidth);
     }
 
+    bool doCAD() {      // CAD (Channel Activity Detection)
+        return radio.scanChannel() != RADIOLIB_CHANNEL_FREE;    // false=channel free | true=RADIOLIB_LORA_DETECTED or CAD failed
+    }
+
+    bool doDIFS() {
+        for (uint8_t i = DIFS_SLOTS; i > 0; i--) {
+            if (doCAD()) return false;
+        }
+        return true;
+    }
+
+    void waitForDIFS() {
+        while (!doDIFS()) {
+            Serial.println("CAD/DIFS failed, retry...");
+        }
+    }
+
+    void doBEB() {
+        int backoffCounter = random(1, backoffMax + 1);
+        while (backoffCounter > 0) {
+            if (doCAD()) {
+                waitForDIFS();  // busy channel: freeze backoff and restart DIFS
+            } else {
+                backoffCounter--;
+            }
+        }
+    }
+
     void sendNewPacket(const String& newPacket) {
         if (!Config.loramodule.txActive) return;
 
@@ -179,6 +211,12 @@ namespace LoRa_Utils {
         #ifdef INTERNAL_LED_PIN
             if (Config.digi.ecoMode != 1) digitalWrite(INTERNAL_LED_PIN, HIGH);     // disabled in Ultra Eco Mode
         #endif
+
+        if (Config.loramodule.cadActive) {
+            waitForDIFS();  // DIFS (Distributed Inter-Frame Space)
+            doBEB();        // BEB  (Binary Exponential Backoff)
+        }
+
         int state = radio.transmit("\x3c\xff\x01" + newPacket);
         transmitFlag = true;
         if (state == RADIOLIB_ERR_NONE) {
@@ -250,7 +288,6 @@ namespace LoRa_Utils {
                         } else {
                             packet = "";
                         }
-                        lastRxTime = millis();
                         return packet;
                     }
                 } else if (state == RADIOLIB_ERR_CRC_MISMATCH) {

src/station_utils.cpp

@@ -25,15 +25,11 @@
 #include "utils.h"
 #include <vector>
 
-#define SECS_TO_WAIT            3   // soon to be deleted...
-
 
 extern Configuration            Config;
-extern uint32_t                 lastRxTime;
 extern String                   fourthLine;
 extern bool                     shouldSleepLowVoltage;
 
-uint32_t lastTxTime             = millis();
 std::vector<LastHeardStation>   lastHeardStations;
 std::vector<String>             blacklist;
 std::vector<String>             managers;
@@ -214,15 +210,11 @@ namespace STATION_Utils {
     }
 
     void processOutputPacketBuffer() {
-        int timeToWait                  = SECS_TO_WAIT * 1000;          // 3 segs between packet Tx and also Rx ???
-        uint32_t lastRx                 = millis() - lastRxTime;
-        uint32_t lastTx                 = millis() - lastTxTime;
-        if (outputPacketBuffer.size() > 0 && lastTx > timeToWait && lastRx > timeToWait) {
+        if (outputPacketBuffer.size() > 0) {
             if (outputPacketBuffer[0].isBeacon) packetIsBeacon = true;
             LoRa_Utils::sendNewPacket(outputPacketBuffer[0].packet);
             if (outputPacketBuffer[0].isBeacon) packetIsBeacon = false;
             outputPacketBuffer.erase(outputPacketBuffer.begin());
-            lastTxTime = millis();
         }
         if (shouldSleepLowVoltage) {
             while (outputPacketBuffer.size() > 0) {