MAX_CURRENT restriction (caps motor shield value)

MotorDriver.cpp

@@ -135,7 +135,11 @@ MotorDriver::MotorDriver(int16_t power_pin, byte signal_pin, byte signal_pin2, i
   // float calculations or libraray code. 
   senseFactorInternal=sense_factor * senseScale; 
   tripMilliamps=trip_milliamps;
-  rawCurrentTripValue=mA2raw(trip_milliamps);
+#ifdef MAX_CURRENT
+  if (MAX_CURRENT > 0 && MAX_CURRENT < tripMilliamps)
+    tripMilliamps = MAX_CURRENT;
+#endif
+  rawCurrentTripValue=mA2raw(tripMilliamps);
 
   if (rawCurrentTripValue + senseOffset > ADCee::ADCmax()) {
     // This would mean that the values obtained from the ADC never

config.example.h

@@ -57,6 +57,21 @@ The configuration file for DCC-EX Command Station
 //   +-----------------------v
 //
 #define MOTOR_SHIELD_TYPE STANDARD_MOTOR_SHIELD
+//
+/////////////////////////////////////////////////////////////////////////////////////
+//
+// If you want to restrict the maximum current LOWER than what your
+// motor shield can provide, you can do that here. For example if you
+// have a motor shield that can provide 5A and your power supply can
+// only provide 2.5A then you should restict the maximum current to
+// 2.25A (90% of 2.5A) so that DCC-EX does shut off the track before
+// your PS does shut DCC-EX. MAX_CURRENT is in mA so for this example
+// it would be 2250, adjust the number according to your PS. If your
+// PS has a higher rating than your motor shield you do not need this.
+// You can use this as well if you are cautious and your trains do not
+// need full current.
+// #define MAX_CURRENT 2250
+//
 /////////////////////////////////////////////////////////////////////////////////////
 //
 // The IP port to talk to a WIFI or Ethernet shield.