Refrain from transmitting if duty cycle exceeded

src/airtime.cpp

@@ -117,6 +117,20 @@ float AirTime::utilizationTXPercent()
     return (float(sum) / float(MS_IN_HOUR)) * 100;
 }
 
+// Get the amount of minutes we have to be silent before we can send again
+uint8_t AirTime::getSilentMinutes(float txPercent, float dutyCycle) 
+{  
+  float newTxPercent = txPercent;
+  for (int8_t i = MINUTES_IN_HOUR-1; i >= 0; --i) {
+      newTxPercent -= ((float)this->utilizationTX[i] / (MS_IN_MINUTE * MINUTES_IN_HOUR / 100));
+      if (newTxPercent < dutyCycle) 
+          return MINUTES_IN_HOUR-1-i;
+  }
+
+  return MINUTES_IN_HOUR;
+}
+
+
 AirTime::AirTime() : concurrency::OSThread("AirTime"),airtimes({}) {
 }
 

src/airtime.h

@@ -29,6 +29,7 @@
 #define PERIODS_TO_LOG 8
 #define MINUTES_IN_HOUR 60
 #define SECONDS_IN_MINUTE 60
+#define MS_IN_MINUTE (SECONDS_IN_MINUTE * 1000)
 #define MS_IN_HOUR (MINUTES_IN_HOUR * SECONDS_IN_MINUTE * 1000)
 
 
@@ -57,6 +58,7 @@ class AirTime : private concurrency::OSThread
     uint32_t getSecondsPerPeriod();
     uint32_t getSecondsSinceBoot();
     uint32_t *airtimeReport(reportTypes reportType);
+    uint8_t getSilentMinutes(float txPercent, float dutyCycle);
 
   private:
     bool firstTime = true;

src/mesh/NodeDB.cpp

@@ -162,6 +162,7 @@ void NodeDB::installDefaultConfig()
     config.has_network = true;
     config.has_bluetooth = true;
     config.lora.tx_enabled = true; // FIXME: maybe false in the future, and setting region to enable it. (unset region forces it off)
+    config.lora.override_duty_cycle = false; 
     config.lora.region = Config_LoRaConfig_RegionCode_UNSET;
     config.lora.modem_preset = Config_LoRaConfig_ModemPreset_LONG_FAST;
     config.lora.hop_limit = HOP_RELIABLE;

src/mesh/Router.cpp

@@ -2,6 +2,7 @@
 #include "Channels.h"
 #include "CryptoEngine.h"
 #include "NodeDB.h"
+#include "MeshRadio.h"
 #include "RTC.h"
 #include "configuration.h"
 #include "main.h"
@@ -188,6 +189,18 @@ ErrorCode Router::send(MeshPacket *p)
 {
     assert(p->to != nodeDB.getNodeNum()); // should have already been handled by sendLocal
 
+    // Abort sending if we are violating the duty cycle
+    if (!config.lora.override_duty_cycle && myRegion->dutyCycle != 100) {
+      float hourlyTxPercent = airTime->utilizationTXPercent();
+      if (hourlyTxPercent > myRegion->dutyCycle) {
+          uint8_t silentMinutes = airTime->getSilentMinutes(hourlyTxPercent, myRegion->dutyCycle); 
+          DEBUG_MSG("WARNING: Duty cycle limit exceeded. Aborting send for now, you can send again in %d minutes.\n", silentMinutes);
+          Routing_Error err = Routing_Error_DUTY_CYCLE_LIMIT;
+          abortSendAndNak(err, p);
+          return err;
+      }
+    }
+
     // PacketId nakId = p->decoded.which_ackVariant == SubPacket_fail_id_tag ? p->decoded.ackVariant.fail_id : 0;
     // assert(!nakId); // I don't think we ever send 0hop naks over the wire (other than to the phone), test that assumption with
     // assert