How would I read strings to turn the project off and on?

[mrburnette]

@alkaothm

how would I add or fix this code so that I would turn the project on and off by typing something in the serial monitor.

Taking the idea far beyond on/off, imagine implementing your own "verbs" to have the Arduino perform your every wish:

Don't Cross The Streams (FP scientific calculator serial co-processor)

This thread started as as fun project of building a floating point calculator that could be "called over RS232" via the main uC processor. Results would be sent back to the requesting processor via RS232. The idea is that the small investment in a ATmel328 (or other) Arduino on a breadboard would provide an inexpensive (approx. $3) capability by offloading the rather large IEEE floating point library (32-bit) to a second Arduino chip on a board-duino. However, even with all the code for parsing…

Another command could be constructed for Digital Pin Write, DPW, and another for Analog Pin Read, APR. As you can see from the snipplets of code below, the implementation is very easy. While manipulating a remote uC’s state over RS232 may seem completely insane, not every design requires near instanteous control; sometimes, the external signals only need to be monitored occasionally and RS232 is a nearly ‘free’ resource in the Arduino world.

void setup()
  pinMode(3, INPUT);      //  sets the digital pin 3 as input
  pinMode(6, INPUT);      //  sets the digital pin 6 as input
  pinMode(7, INPUT);      //  sets the digital pin 7 as input
  pinMode(8, INPUT);      //  sets the digital pin 8 as input
  pinMode(9, INPUT);      //  sets the digital pin 9 as input
  pinMode(10, INPUT);      // sets the digital pin 10 as input
  pinMode(11, INPUT);      // sets the digital pin 11 as input
  pinMode(12, INPUT);      // sets the digital pin 12 as input
...
    case 22:    //DPR DigitalPin Read # valid 2 - 13  Return 0, 1 for state or 2 for Error
            if (verbose) {Serial.print(F("Prompting for Digital Pin Number 2 - 13: ")); }
            DigPinNo = Serial.parseInt(); 
            if (DigPinNo <2 || DigPinNo > 13) {
              if (verbose) { Serial.print(DigPinNo);
                Serial.print(" Pin# Error"); break; }
                Serial << Err; break; }
            if (verbose) { Serial.print(DigPinNo); }
            if (verbose) {Serial.print(F(" Logic State = ")); }
            Serial << digitalRead(DigPinNo);
            if (verbose) {Serial.println(); }
            break;