Railcom sample window

DCCWaveform.cpp

@@ -116,18 +116,20 @@ DCCWaveform::DCCWaveform( byte preambleBits, bool isMain) {
   bits_sent = 0;
 }
     
+bool DCCWaveform::railcomPossible=false;     // High accuracy only
 volatile bool DCCWaveform::railcomActive=false;     // switched on by user
+volatile bool DCCWaveform::railcomSampleWindow=false; // true during packet transmit
 volatile bool DCCWaveform::railcomDebug=false;     // switched on by user
 
 bool DCCWaveform::setRailcom(bool on, bool debug) {
-  if (on) {
+  if (on && railcomPossible) {
-    // TODO check possible
     railcomActive=true;
     railcomDebug=debug;
   }
   else {
     railcomActive=false;
     railcomDebug=false;
+    railcomSampleWindow=false;
   } 
   return railcomActive;
 }
@@ -147,7 +149,17 @@ void DCCWaveform::interrupt2() {
     // that the reminder doesn't block a more urgent packet. 
     reminderWindowOpen=transmitRepeats==0 && remainingPreambles<4 && remainingPreambles>1;
     if (remainingPreambles==1) promotePendingPacket();
-    else if (remainingPreambles==10 && isMainTrack && railcomActive) DCCTimer::ackRailcomTimer();
+    else if (isMainTrack && railcomActive) {
+      if (remainingPreambles==10) {
+        // cutout has started so the railcom timer needs to end the cutout at next
+        // cutout timer tick. 
+        DCCTimer::ackRailcomTimer();        
+      }
+      else if (remainingPreambles==5) {
+        // cutout has ended so its now possible to poll the railcom detectors
+        railcomSampleWindow=true;
+      }
+    }
     // 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.
     else DCCTimer::updateMinimumFreeMemoryISR(22); 
@@ -172,11 +184,14 @@ void DCCWaveform::interrupt2() {
       // preamble for next packet will start...
       remainingPreambles = requiredPreambles;
       
-      // set the railcom coundown to trigger half way 
+      // Set the railcom coundown to trigger half way 
       // through the first preamble bit.
       // Note.. we are still sending the last packet bit
-      //    and we then have to allow for the packet end bit
+      //    but the timer code allows for this
-      if (isMainTrack && railcomActive) DCCTimer::startRailcomTimer(9);
+      if (isMainTrack && railcomActive) {
+        railcomSampleWindow=false; // about to cutout, stop reading railcom data. 
+        DCCTimer::startRailcomTimer(9);
+      }
       }
   }  
 }
@@ -230,7 +245,7 @@ void DCCWaveform::promotePendingPacket() {
       // Fortunately reset and idle packets are the same length
       // Note: If railcomDebug is on, then we send resets to the main
       //       track instead of idles. This means that all data will be zeros
-      //       and only the porersets will be ones, making it much
+      //       and only the presets will be ones, making it much
       //       easier to read on a logic analyser.
       memcpy( transmitPacket, (isMainTrack && (!railcomDebug)) ? idlePacket : resetPacket, sizeof(idlePacket));
       transmitLength = sizeof(idlePacket);

DCCWaveform.h

@@ -85,8 +85,13 @@ class DCCWaveform {
     void schedulePacket(const byte buffer[], byte byteCount, byte repeats);
     bool isReminderWindowOpen();
     void promotePendingPacket();
+    static void setRailcomPossible(bool yes) {
+          railcomPossible=yes;
+          if (!yes) setRailcom(false,false);
+    }
     static bool setRailcom(bool on, bool debug);
     static bool isRailcom() {return railcomActive;}
+    static bool isRailcomSampleWindow() {return railcomSampleWindow;}
     
   private:
 #ifndef ARDUINO_ARCH_ESP32
@@ -112,9 +117,10 @@ class DCCWaveform {
     byte pendingPacket[MAX_PACKET_SIZE+1]; // +1 for checksum
     byte pendingLength;
     byte pendingRepeats;
-    static volatile bool railcomActive;     // switched on by user
+    static bool railcomPossible; // High accuracy mode only
-    static volatile bool railcomDebug;     // switched on by user
+    static volatile bool railcomActive;   // switched on by user
-    
+    static volatile bool railcomDebug;    // switched on by user
+    static volatile bool railcomSampleWindow; // when safe to sample   
 #ifdef ARDUINO_ARCH_ESP32
   static RMTChannel *rmtMainChannel;
   static RMTChannel *rmtProgChannel;

IO_I2CRailcom.h

@@ -47,11 +47,11 @@
 #include "IODevice.h"
 #include "I2CManager.h"
 #include "DIAG.h"
+#include "DCCWaveform.h"
 
 // Debug and diagnostic defines, enable too many will result in slowing the driver
 #define DIAG_I2CRailcom
 #define DIAG_I2CRailcom_data
-#define DIAG_I2CRailcom_reg
 
 class I2CRailcom : public IODevice {
 private: 
@@ -62,7 +62,7 @@ private:
   const uint8_t STOP_BIT = 0x00;    // Value LCR bit 2 
   const uint8_t PARITY_ENA = 0x00;  // Value LCR bit 3
   const  uint8_t PARITY_TYPE = 0x00; // Value LCR bit 4
-  const uint32_t BAUD_RATE = 9600;
+  const uint32_t BAUD_RATE = 250000;
   const  uint8_t PRESCALER = 0x01;   // Value MCR bit 7  
   const unsigned long SC16IS752_XTAL_FREQ_RAILCOM = 16000000; // Baud rate for Railcom signal
   byte _inbuf[65];
@@ -106,7 +106,8 @@ public:
     // Read responses from device
     if (_deviceState!=DEVSTATE_NORMAL) return;
 
-    // TODO - return if in cutout or cutout very soon.  
+    // return if in cutout or cutout very soon.  
+    if (!DCCWaveform::isRailcomSampleWindow()) return; 
 
     // flip channels each loop
     if (_nPins>1) _UART_CH=_UART_CH?0:1;

TrackManager.cpp

@@ -338,13 +338,17 @@ bool TrackManager::setTrackMode(byte trackToSet, TRACK_MODE mode, int16_t dcAddr
       // if we discover that HA mode was globally impossible
       // we must adjust the trackPWM capabilities
       DIAG(F("High Accuracy & Railcom disabled"));
+      DCCWaveform::setRailcomPossible(false);
       FOR_EACH_TRACK(t) {
 	track[t]->trackPWM=false;
 	//DIAG(F("Track %c trackPWM 0 (global override)"), t+'A');
       }
       DCCTimer::clearPWM(); // has to be AFTER trackPWM changes because if trackPWM==true this is undone for  that track
     }
-    else DIAG(F("High Accuracy Enabled"));
+    else {
+      DIAG(F("High Accuracy Enabled"));
+      DCCWaveform::setRailcomPossible(true);
+    }
 #else
     // For ESP32 we just reinitialize the DCC Waveform
     DCCWaveform::begin();