Add support for no output pin toggling

Author: NT7S

README.md

@@ -44,7 +44,7 @@ If you need to check to see if the Morse library is currently sending the conten
 
 The sending speed can be changed on-the-fly by using the _setWPM()_ method. The parameter is typed using a _float_ so that fractional words per minute can be specified. Why would you want to do this? In case you need to send Morse code using a very long integration time such as with the QRSS operating mode. For example, a setting of 0.2 WPM sets a Morse code "dit" length of 6 seconds.
 
-If you don't want to have the library directly control a digital I/O pin, you may have your sketch poll the boolean _tx_ member variable and act on it accordingly within their periodic 1 ms function.
+If you don't want to have the library directly control a digital I/O pin, you may have your sketch poll the boolean _tx_ member variable and act on it accordingly within their periodic 1 ms function. Set the output pin parameter in the constructor to 0.
 
 Startup Conditions and Constraints
 ----------------------------------
@@ -61,7 +61,8 @@ Public Methods
  *
  * Create an instance of the Morse class.
  *
- * tx_pin - Arduino pin used as the output by this library.
+ * tx_pin - Arduino pin used as the output by this library. Will not toggle an
+ *          output pin if set to 0.
  * init_wpm - Sending speed in words per minute.
  *
  */

src/Morse.cpp

@@ -36,7 +36,8 @@
  *
  * Create an instance of the Morse class.
  *
- * tx_pin - Arduino pin used as the output by this library.
+ * tx_pin - Arduino pin used as the output by this library. Will not toggle an
+ *          output pin if set to 0.
  * init_wpm - Sending speed in words per minute.
  *
  */
@@ -48,7 +49,10 @@ Morse::Morse(uint8_t tx_pin, float init_wpm) : output_pin(tx_pin)
 
 	setWPM(init_wpm);
 
-	pinMode(output_pin, OUTPUT);
+	if(output_pin)
+	{
+		pinMode(output_pin, OUTPUT);
+	}
 
 	cur_state = State::IDLE;
 	next_state = State::IDLE;
@@ -223,7 +227,10 @@ void Morse::update()
     case State::PREAMBLE:
       // Transmitter on
       tx = true;
-			digitalWrite(output_pin, HIGH);
+			if(output_pin)
+			{
+				digitalWrite(output_pin, HIGH);
+			}
 
       // When done waiting, go back to IDLE state to start the message
       if(cur_timer > cur_state_end)
@@ -235,12 +242,18 @@ void Morse::update()
     case State::DIT:
     case State::DAH:
       tx = true;
-			digitalWrite(output_pin, HIGH);
+			if(output_pin)
+			{
+				digitalWrite(output_pin, HIGH);
+			}
 
       if(cur_timer > cur_state_end)
       {
         tx = false;
-				digitalWrite(output_pin, LOW);
+				if(output_pin)
+				{
+					digitalWrite(output_pin, LOW);
+				}
 
         cur_state_end = cur_timer + dit_length;
         cur_state = State::DITDELAY;
@@ -252,7 +265,10 @@ void Morse::update()
 		case State::MSGDELAY:
     case State::EOMDELAY:
       tx = false;
-			digitalWrite(output_pin, LOW);
+			if(output_pin)
+			{
+				digitalWrite(output_pin, LOW);
+			}
 
       if(cur_timer > cur_state_end)
       {

src/Morse.h

@@ -28,7 +28,6 @@
 
 #include "Arduino.h"
 
-
 // Constants
 constexpr uint8_t DEFAULT_OUTPUT_PIN = LED_BUILTIN;
 constexpr float DEFAULT_WPM = 25;