Handle shields with common fault pins (Pololu)

DCCEXParser.cpp

@@ -436,7 +436,8 @@ void DCCEXParser::parse(Print *stream, byte *com, bool blocking)
         {
             POWERMODE mode = opcode == '1' ? POWERMODE::ON : POWERMODE::OFF;
             DCC::setProgTrackSyncMain(false); // Only <1 JOIN> will set this on, all others set it off
-            if (params == 0)
+            if (params == 0 ||
+		(MotorDriver::commonFaultPin && p[0] != HASH_KEYWORD_JOIN)) // commonFaultPin prevents individual track handling
             {
                 DCCWaveform::mainTrack.setPowerMode(mode);
                 DCCWaveform::progTrack.setPowerMode(mode);

DCCWaveform.cpp

@@ -40,6 +40,7 @@ void DCCWaveform::begin(MotorDriver * mainDriver, MotorDriver * progDriver) {
   mainTrack.setPowerMode(POWERMODE::OFF);      
   progTrack.setPowerMode(POWERMODE::OFF);
   MotorDriver::usePWM= mainDriver->isPWMCapable() && progDriver->isPWMCapable();
+  MotorDriver::commonFaultPin = (mainDriver->getFaultPin() == progDriver->getFaultPin());
   if (MotorDriver::usePWM) DIAG(F("\nWaveform using PWM pins for accuracy."));
   else  DIAG(F("\nWaveform accuracy limited by signal pin configuration."));
   DCCTimer::begin(DCCWaveform::interruptHandler);     
@@ -125,10 +126,23 @@ void DCCWaveform::checkPowerOverload() {
       lastCurrent=motorDriver->getCurrentRaw();
       if (lastCurrent < 0) {
 	  // We have a fault pin condition to take care of
-	  DIAG(F("\n*** %S FAULT PIN ACTIVE TOGGLE POWER ON THIS OR BOTH TRACKS ***\n"), isMainTrack ? F("MAIN") : F("PROG"));
 	  lastCurrent = -lastCurrent;
-      }
+	  setPowerMode(POWERMODE::OVERLOAD); // Turn off, decide later how fast to turn on again
+	  if (MotorDriver::commonFaultPin) {
 	      if (lastCurrent <= tripValue) {
+		setPowerMode(POWERMODE::ON); // maybe other track
+	      }
+	      // Write this after the fact as we want to turn on as fast as possible
+	      // because we don't know which output actually triggered the fault pin
+	      DIAG(F("\n*** COMMON FAULT PIN ACTIVE - TOGGLED POWER on %S ***\n"), isMainTrack ? F("MAIN") : F("PROG"));
+	  } else {
+	      DIAG(F("\n*** %S FAULT PIN ACTIVE - OVERLOAD ***\n"), isMainTrack ? F("MAIN") : F("PROG"));
+	      if (lastCurrent < tripValue) {
+		  lastCurrent = tripValue; // exaggerate
+	      }
+	  }
+      }
+      if (lastCurrent < tripValue) {
         sampleDelay = POWER_SAMPLE_ON_WAIT;
 	if(power_good_counter<100)
 	  power_good_counter++;

MotorDriver.cpp

@@ -27,6 +27,7 @@
 #define isLOW(fastpin)    (!isHIGH(fastpin))
 
 bool MotorDriver::usePWM=false;
+bool MotorDriver::commonFaultPin=false;
        
 MotorDriver::MotorDriver(byte power_pin, byte signal_pin, byte signal_pin2, int8_t brake_pin,
                          byte current_pin, float sense_factor, unsigned int trip_milliamps, byte fault_pin) {
@@ -116,10 +117,15 @@ void MotorDriver::setSignal( bool high) {
    }
 }
 
+/*
+ * Return the current reading as pin reading 0 to 1023. If the fault
+ * pin is activated return a negative current to show active fault pin.
+ * As there is no -0, ceat a little and return -1 in that case.
+ */
 int MotorDriver::getCurrentRaw() {
   int current = analogRead(currentPin);
   if (faultPin != UNUSED_PIN && isLOW(fastFaultPin) && isHIGH(fastPowerPin))
-      return -current;
+      return (current == 0 ? -1 : -current);
   return current;
   // IMPORTANT:  This function can be called in Interrupt() time within the 56uS timer
   //             The default analogRead takes ~100uS which is catastrphic

MotorDriver.h

@@ -46,6 +46,10 @@ class MotorDriver {
     }
     bool isPWMCapable();
     static bool usePWM;
+    static bool commonFaultPin; // This is a stupid motor shield which has only a common fault pin for both outputs
+    inline byte getFaultPin() {
+	return faultPin;
+    }
     
   private:
     void  getFastPin(const FSH* type,int pin, bool input, FASTPIN & result);

MotorDrivers.h

@@ -30,7 +30,7 @@
 // Pololu Motor Shield
 #define POLOLU_MOTOR_SHIELD F("POLOLU_MOTOR_SHIELD"),                                                 \
                             new MotorDriver( 9, 7, UNUSED_PIN,         -4, A0, 18, 3000, 12), \
-                            new MotorDriver(10, 8, UNUSED_PIN, UNUSED_PIN, A1, 18, 3000, UNUSED_PIN)
+                            new MotorDriver(10, 8, UNUSED_PIN, UNUSED_PIN, A1, 18, 3000, 12)
 //
 // Actually, on the Pololu MC33926 shield the enable lines are tied together on pin 4 and the
 // pins 9 and 10 work as "inverted brake" but as we turn on and off the tracks individually
@@ -38,8 +38,8 @@
 // version of the code always will be high. That means this config is not usable for generating
 // a railcom cuotout in the future. For that one must wire the second ^D2 to pin 2 and define
 // the motor driver like this:
-//                          new MotorDriver(4, 7, UNUSED_PIN,  -9, A0, 18, 3000,         12)
+//                          new MotorDriver(4, 7, UNUSED_PIN,  -9, A0, 18, 3000, 12), \
-//                          new MotorDriver(2, 8, UNUSED_PIN, -10, A1, 18, 3000, UNUSED_PIN)
+//                          new MotorDriver(2, 8, UNUSED_PIN, -10, A1, 18, 3000, 12)
 // See Pololu dial_mc33926_shield_schematic.pdf and truth table on page 17 of the MC33926 data sheet.
 
 // Firebox Mk1

WiThrottle.cpp

@@ -133,6 +133,8 @@ void WiThrottle::parse(RingStream * stream, byte * cmdx) {
        case 'P':  
             if (cmd[1]=='P' && cmd[2]=='A' )  {  //PPA power mode 
               DCCWaveform::mainTrack.setPowerMode(cmd[3]=='1'?POWERMODE::ON:POWERMODE::OFF);
+	      if (MotorDriver::commonFaultPin) // commonFaultPin prevents individual track handling
+		DCCWaveform::progTrack.setPowerMode(cmd[3]=='1'?POWERMODE::ON:POWERMODE::OFF);
               StringFormatter::send(stream,F("PPA%x\n"),DCCWaveform::mainTrack.getPowerMode()==POWERMODE::ON);
               lastPowerState = (DCCWaveform::mainTrack.getPowerMode()==POWERMODE::ON); //remember power state sent for comparison later
             }