5.2.13

DCC.cpp

@@ -595,7 +595,7 @@ void DCC::loop()  {
 
 void DCC::issueReminders() {
   // if the main track transmitter still has a pending packet, skip this time around.
-  if ( DCCWaveform::mainTrack.getPacketPending()) return;
+  if (!DCCWaveform::mainTrack.isReminderWindowOpen()) return;
   // Move to next loco slot.  If occupied, send a reminder.
   int reg = lastLocoReminder+1;
   if (reg > highestUsedReg) reg = 0;  // Go to start of table
@@ -620,14 +620,23 @@ bool DCC::issueReminder(int reg) {
        case 1: // remind function group 1 (F0-F4)
           if (flags & FN_GROUP_1)
               setFunctionInternal(loco,0, 128 | ((functions>>1)& 0x0F) | ((functions & 0x01)<<4)); // 100D DDDD
+#ifdef DISABLE_FUNCTION_REMINDERS
+          flags&= ~FN_GROUP_1;  // dont send them again
+#endif
           break;
        case 2: // remind function group 2 F5-F8
           if (flags & FN_GROUP_2)
               setFunctionInternal(loco,0, 176 | ((functions>>5)& 0x0F));                           // 1011 DDDD
+#ifdef DISABLE_FUNCTION_REMINDERS
+          flags&= ~FN_GROUP_2;  // dont send them again
+#endif
           break;
        case 3: // remind function group 3 F9-F12
           if (flags & FN_GROUP_3)
               setFunctionInternal(loco,0, 160 | ((functions>>9)& 0x0F));                           // 1010 DDDD
+#ifdef DISABLE_FUNCTION_REMINDERS
+          flags&= ~FN_GROUP_3;  // dont send them again
+#endif
           break;
        case 4: // remind function group 4 F13-F20
           if (flags & FN_GROUP_4)

DCCWaveform.cpp

@@ -106,6 +106,7 @@ void DCCWaveform::interruptHandler() {
 DCCWaveform::DCCWaveform( byte preambleBits, bool isMain) {
   isMainTrack = isMain;
   packetPending = false;
+  reminderWindowOpen = false;
   memcpy(transmitPacket, idlePacket, sizeof(idlePacket));
   state = WAVE_START;
   // The +1 below is to allow the preamble generator to create the stop bit
@@ -127,9 +128,15 @@ void DCCWaveform::interrupt2() {
   if (remainingPreambles > 0 ) {
     state=WAVE_MID_1;  // switch state to trigger LOW on next interrupt
     remainingPreambles--;
+
+    // As we get to the end of the preambles, open the reminder window.
+    // This delays any reminder insertion until the last moment so
+    // that the reminder doesn't block a more urgent packet. 
+    reminderWindowOpen=transmitRepeats==0 && remainingPreambles<4 && remainingPreambles>1;
+    if (remainingPreambles==1) promotePendingPacket();
     // Update free memory diagnostic as we don't have anything else to do this time.
     // Allow for checkAck and its called functions using 22 bytes more.
-    DCCTimer::updateMinimumFreeMemoryISR(22); 
+    else DCCTimer::updateMinimumFreeMemoryISR(22); 
     return;
   }
 
@@ -148,30 +155,9 @@ void DCCWaveform::interrupt2() {
     if (bytes_sent >= transmitLength) {
       // end of transmission buffer... repeat or switch to next message
       bytes_sent = 0;
+      // preamble for next packet will start...
       remainingPreambles = requiredPreambles;
-
-      if (transmitRepeats > 0) {
-        transmitRepeats--;
       }
-      else if (packetPending) {
-        // Copy pending packet to transmit packet
-        // a fixed length memcpy is faster than a variable length loop for these small lengths
-        // for (int b = 0; b < pendingLength; b++) transmitPacket[b] = pendingPacket[b];
-        memcpy( transmitPacket, pendingPacket, sizeof(pendingPacket));
-        
-        transmitLength = pendingLength;
-        transmitRepeats = pendingRepeats;
-        packetPending = false;
-        clearResets();
-      }
-      else {
-        // Fortunately reset and idle packets are the same length
-        memcpy( transmitPacket, isMainTrack ? idlePacket : resetPacket, sizeof(idlePacket));
-        transmitLength = sizeof(idlePacket);
-        transmitRepeats = 0;
-        if (getResets() < 250) sentResetsSincePacket++; // only place to increment (private!)
-      }
-    }
   }  
 }
 #pragma GCC pop_options
@@ -193,8 +179,39 @@ void DCCWaveform::schedulePacket(const byte buffer[], byte byteCount, byte repea
   packetPending = true;
   clearResets();
 }
-bool DCCWaveform::getPacketPending() {
+
-  return packetPending;
+bool DCCWaveform::isReminderWindowOpen() {
+  return reminderWindowOpen && ! packetPending;
+}
+
+void DCCWaveform::promotePendingPacket() {
+    // fill the transmission packet from the pending packet
+    
+    // Just keep going if repeating  
+    if (transmitRepeats > 0) {
+        transmitRepeats--;
+        return;
+      }
+
+    if (packetPending) {
+        // Copy pending packet to transmit packet
+        // a fixed length memcpy is faster than a variable length loop for these small lengths
+        // for (int b = 0; b < pendingLength; b++) transmitPacket[b] = pendingPacket[b];
+        memcpy( transmitPacket, pendingPacket, sizeof(pendingPacket));
+        
+        transmitLength = pendingLength;
+        transmitRepeats = pendingRepeats;
+        packetPending = false;
+        clearResets();
+        return;
+      }
+      
+      // nothing to do, just send idles or resets
+      // Fortunately reset and idle packets are the same length
+      memcpy( transmitPacket, isMainTrack ? idlePacket : resetPacket, sizeof(idlePacket));
+      transmitLength = sizeof(idlePacket);
+      transmitRepeats = 0;
+      if (getResets() < 250) sentResetsSincePacket++; // only place to increment (private!)
 }
 #endif
 
@@ -266,15 +283,15 @@ void DCCWaveform::schedulePacket(const byte buffer[], byte byteCount, byte repea
   }
 }
 
-bool DCCWaveform::getPacketPending() {
+bool DCCWaveform::isReminderWindowOpen() {
   if(isMainTrack) {
     if (rmtMainChannel == NULL)
-      return true;
+      return false;
-    return rmtMainChannel->busy();
+    return !rmtMainChannel->busy();
   } else {
     if (rmtProgChannel == NULL)
-      return true;
+      return false;
-    return rmtProgChannel->busy();
+    return !rmtProgChannel->busy();
   }
 }
 void IRAM_ATTR DCCWaveform::loop() {

DCCWaveform.h

@@ -76,11 +76,13 @@ class DCCWaveform {
     };
 #endif
     void schedulePacket(const byte buffer[], byte byteCount, byte repeats);
-    bool getPacketPending();
+    bool isReminderWindowOpen();
+    void promotePendingPacket();
     
   private:
 #ifndef ARDUINO_ARCH_ESP32
     volatile bool packetPending;
+    volatile bool reminderWindowOpen;
     volatile byte sentResetsSincePacket;
 #else
     volatile uint32_t resetPacketBase;

version.h

@@ -3,7 +3,9 @@
 
 #include "StringFormatter.h"
 
-#define VERSION "5.2.13"
+#define VERSION "5.2.14"
+// 5.2.14 - Reminder window DCC packet optimization
+//        - Optional #define DISABLE_FUNCTION_REMINDERS 
 // 5.2.13 - EXRAIL STEALTH 
 // 5.2.12 - ESP32 add AP mode LCD messages with SSID/PW for
 //        - STM32 change to UID_BASE constants in DCCTimerSTM32 rather than raw hex addresses for UID registers