POM Read

DCC.cpp

@@ -389,6 +389,25 @@ void DCC::writeCVByteMain(int cab, int cv, byte bValue)  {
   DCCWaveform::mainTrack.schedulePacket(b, nB, 4);
 }
 
+//
+// readCVByteMain: Read a byte with PoM on main.
+// This requires Railcom active 
+//
+void DCC::readCVByteMain(int cab, int cv, ACK_CALLBACK callback)  {
+  byte b[5];
+  byte nB = 0;
+  if (cab > HIGHEST_SHORT_ADDR)
+    b[nB++] = highByte(cab) | 0xC0;    // convert train number into a two-byte address
+
+  b[nB++] = lowByte(cab);
+  b[nB++] = cv1(READ_BYTE_MAIN, cv); // any CV>1023 will become modulus(1024) due to bit-mask of 0x03
+  b[nB++] = cv2(cv);
+  b[nB++] = 0;
+
+  DCCWaveform::mainTrack.schedulePacket(b, nB, 4);
+  Railcom::anticipate(cab,cv,callback);
+}
+
 //
 // writeCVBitMain: Write a bit of a byte with PoM on main. This writes
 // the 5 byte sized packet to implement this DCC function

DCC.h

@@ -64,6 +64,8 @@ public:
   static uint8_t getThrottleFrequency(int cab);
   static bool getThrottleDirection(int cab);
   static void writeCVByteMain(int cab, int cv, byte bValue);
+  static void readCVByteMain(int cab, int cv, ACK_CALLBACK callback);
+  
   static void writeCVBitMain(int cab, int cv, byte bNum, bool bValue);
   static void setFunction(int cab, byte fByte, byte eByte);
   static bool setFn(int cab, int16_t functionNumber, bool on);
@@ -128,6 +130,7 @@ private:
   // NMRA codes #
   static const byte SET_SPEED = 0x3f;
   static const byte WRITE_BYTE_MAIN = 0xEC;
+  static const byte READ_BYTE_MAIN = 0xE4;
   static const byte WRITE_BIT_MAIN = 0xE8;
   static const byte WRITE_BYTE = 0x7C;
   static const byte VERIFY_BYTE = 0x74;

DCCEXParser.cpp

@@ -480,6 +480,14 @@ void DCCEXParser::parseOne(Print *stream, byte *com, RingStream * ringStream)
 	break;
       DCC::writeCVByteMain(p[0], p[1], p[2]);
       return;
+    
+    case 'r': // READ CV on MAIN <r CAB CV>  Requires Railcom
+      if (params != 2)
+	break;
+      if (!DCCWaveform::isRailcom()) break;
+      if (!stashCallback(stream, p, ringStream)) break;
+      DCC::readCVByteMain(p[0], p[1],callback_r);
+      return;
 
     case 'b': // WRITE CV BIT ON MAIN <b CAB CV BIT VALUE>
       if (params != 4)
@@ -1417,6 +1425,12 @@ void DCCEXParser::callback_R(int16_t result)
     commitAsyncReplyStream();
 }
 
+void DCCEXParser::callback_r(int16_t result)
+{
+    StringFormatter::send(getAsyncReplyStream(), F("<r MAIN %d %d %d >\n"), stashP[0], stashP[1], result);
+    commitAsyncReplyStream();
+}
+
 void DCCEXParser::callback_Rloco(int16_t result) {
   const FSH * detail;
   if (result<=0) {

DCCEXParser.h

@@ -68,7 +68,8 @@ struct DCCEXParser
     static void callback_W(int16_t result);
     static void callback_W4(int16_t result);
     static void callback_B(int16_t result);        
-    static void callback_R(int16_t result);
+    static void callback_R(int16_t result); // prog
+    static void callback_r(int16_t result); // main
     static void callback_Rloco(int16_t result);
     static void callback_Wloco(int16_t result);
     static void callback_Wconsist(int16_t result);

Railcom.cpp

@@ -145,6 +145,10 @@ Railcom::Railcom(uint16_t blockvpin) {
     lastChannel1Loco=0;
     vpin=blockvpin;
 }
+uint16_t Railcom::expectLoco=0;
+uint16_t Railcom::expectCV=0;
+uint16_t Railcom::expectWait=0;
+ACK_CALLBACK Railcom::expectCallback=0;
 
 
 // Process is called by a raw data collector. 
@@ -170,6 +174,30 @@ void Railcom::process(uint8_t * inbound, uint8_t length) {
       }
     }
 
+    if (expectCV && DCCWaveform::getRailcomLastLocoAddress()==expectLoco) {
+        if (length>=4) {
+            auto v2=GETHIGHFLASH(decode,inbound[2]);
+            auto v3=GETHIGHFLASH(decode,inbound[3]);
+            uint16_t packet=(v2<<6) | (v3 & 0x3f);
+            // packet is 12 bits TTTTDDDDDDDD
+            byte type=(packet>>8) & 0x0F;   
+            byte data= packet & 0xFF;
+            if (type==RMOB_POM) {
+                DIAG(F("POM READ loco=%d cv(%d)=%d/0x%x"), expectLoco, expectCV,data,data);
+                expectCallback(data);
+                expectCV=0;
+            }
+        }
+        if (expectCV) { // still waiting 
+            expectWait--;
+            if (expectWait==0) {
+                DIAG(F("POM READ loco=%d cv(%d) FAIL"), expectLoco, expectCV);
+                expectCallback(-1);
+                expectCV=0;
+            }
+        }
+        
+    } 
 
     auto v1=GETHIGHFLASH(decode,inbound[0]);
     auto v2=(length>1) ? GETHIGHFLASH(decode,inbound[1]):INV;

Railcom.h

@@ -22,6 +22,8 @@
 #define Railcom_h
 #include "Arduino.h"
 
+typedef void (*ACK_CALLBACK)(int16_t result);
+
 class Railcom {
   public:
     Railcom(uint16_t vpin);
@@ -31,8 +33,16 @@ class Railcom {
                >0: loco id
     */
   void process(uint8_t * inbound,uint8_t length);
+  static void anticipate(uint16_t loco, uint16_t cv, ACK_CALLBACK callback) { 
+    expectLoco=loco;
+    expectCV=cv;
+    expectWait=10;  // channel3 packets
+    expectCallback=callback;
+    };
   
   private:
+  static uint16_t expectCV,expectLoco,expectWait;
+  static ACK_CALLBACK expectCallback;
   void noData();
   uint16_t vpin;
  uint8_t holdoverHigh,holdoverLow;