removed channel_i constraining--fixing tricky bug

channel constraining is a BAD idea....ie: when the user tries to set Ch8
even though they set numChannels to only 7, it is BAD to constrain their
channel input and set what they think is their Ch8 value on Ch7...as
this is a really hard to find bug. Rather, it is best to not do
anything, thereby letting the user know when they see stuff not working
that they are not actually setting the channel. So...I fixed this in the
whole .cpp file...NO MORE CONSTRAINING CHANNEL INDEXES INPUT BY THE
USER!!! Just don't do anything if their channel_i value is invalid.
DONE! This stinking bug cost me a couple hrs lost time.

eRCaGuy_PPM_Writer.cpp

@@ -118,7 +118,7 @@ ISR(TIMER1_OVF_vect,ISR_BLOCK) //Timer1's counter has overflowed
 //--------------------------------------------------------------------------------------------------------
 //compareMatchISR
 //-Here is where the magic happens (ie: the actual writing of the PPM signal)
-//-NESTED INTERRUPTS ENABLED HERE 
+//-NESTED INTERRUPTS ENABLED HERE <--CANCEL THAT; IT'S A BAD IDEA; see above: if ISR_BLOCK is in use, it does NOT allow nested interrupts 
 //--------------------------------------------------------------------------------------------------------
 inline void eRCaGuy_PPM_Writer::compareMatchISR()
 {
@@ -382,17 +382,17 @@ void eRCaGuy_PPM_Writer::end()
 //--------------------------------------------------------------------------------------------------------
 boolean eRCaGuy_PPM_Writer::readChannelFlag(byte channel_i)
 {
-  bool flagVal;
-  //ensure a valid channel
-  // channel_i = constrain(channel_i,0,_numChannels - 1);
-  channel_i = min(channel_i,_numChannels - 1); //same as above, since 0 lower constraint on unsigned value is meaningless
-
-  //ensure atomic access to volatile variables
-  ATOMIC_BLOCK(ATOMIC_RESTORESTATE)
+  bool flagVal = false;
+  //only perform this action on a valid channel
+  if (channel_i < _numChannels)
   {
-    flagVal = bitRead(_channelFlags,channel_i);
-    if (flagVal==true) //if read true, reset the flag
-      bitClear(_channelFlags,channel_i);
+    //ensure atomic access to volatile variables
+    ATOMIC_BLOCK(ATOMIC_RESTORESTATE)
+    {
+      flagVal = bitRead(_channelFlags,channel_i);
+      if (flagVal==true) //if read true, reset the flag
+        bitClear(_channelFlags,channel_i);
+    }
   }
   return flagVal;
 }
@@ -410,15 +410,17 @@ boolean eRCaGuy_PPM_Writer::readChannelFlag(byte channel_i)
 //--------------------------------------------------------------------------------------------------------
 void eRCaGuy_PPM_Writer::setChannelVal(byte channel_i, unsigned int val)
 {
-  //constrain within valid bounds
-  val = constrain(val,_minChannelVal,_maxChannelVal);
-  // channel_i = constrain(channel_i,0,_numChannels - 1);
-  channel_i = min(channel_i,_numChannels - 1); //same as above, since 0 lower constraint on unsigned value is meaningless
-
-  //ensure atomic access to volatile variables
-  ATOMIC_BLOCK(ATOMIC_RESTORESTATE)
+  //only perform this action on a valid channel
+  if (channel_i < _numChannels)
   {
-    _channels[channel_i] = val;
+    //constrain within valid bounds
+    val = constrain(val,_minChannelVal,_maxChannelVal);
+
+    //ensure atomic access to volatile variables
+    ATOMIC_BLOCK(ATOMIC_RESTORESTATE)
+    {
+      _channels[channel_i] = val;
+    }
   }
 }
 
@@ -553,9 +555,14 @@ void eRCaGuy_PPM_Writer::setPPMPolarity(boolean PPMPolarity)
 unsigned int eRCaGuy_PPM_Writer::getChannelVal(byte channel_i)
 {
   //Note: forced atomic access NOT required on _numChannels and _channels below since they are only being READ here, AND since they are NOT ever written to (modified) in an ISR 
-  // channel_i = constrain(channel_i,0,_numChannels - 1);   
-  channel_i = min(channel_i,_numChannels - 1); //same as above, since 0 lower constraint on unsigned value is meaningless
-  return _channels[channel_i];
+
+  //only perform this action on a valid channel
+  if (channel_i < _numChannels)
+  {
+    return _channels[channel_i];
+  }
+  else //not a valid channel 
+    return 0;
 }
 
 //--------------------------------------------------------------------------------------------------------