Finite state machine on arduino with Serial Interrupts

[StefanL38]

rhetoric question: which code will be used by newcomers?

the code that comes close to their needs combined with easyness to understand how to apply it.

I have written a small tutorial with a demo-code how to use SafeString non-blocking serial input

Non-blocking receiving of commands over serial interface using the SafeString-library [code example]

This is another small tutorial that shall demonstrate how to receive commands over a serial interface in a non-blocking manner using the SafeString-library If you are in a hurry to throw together code as fast as possible jump to posting # 2 non-blocking means the code has a fast running function loop() that is able to check for button-presses check for IO-pin changing their state read in sensors etc and in parallel listen to the serial interface all the time and in case all characters of a…

and then derived from there a code that demonstrates LED switching on/off using serial commands that set states of a fsm
That is what I call a starting point

#include "SafeStringReader.h"

createSafeStringReader(myInputReader, 5, " ,\r\n");

const byte LED_pin = 13;

const byte fsm_idling         = 1;
const byte fsm_switchLEDOn    = 2;
const byte fsm_waitWithLEDOn  = 3;
const byte fsm_SwitchLEDOFF   = 4;

byte myStateVar;

unsigned long myWaitTimer;

const unsigned long LedOnTime = 10000;

// easy to use helper-function for non-blocking timing
boolean TimePeriodIsOver (unsigned long &startOfPeriod, unsigned long TimePeriod) {
  unsigned long currentMillis  = millis();
  if ( currentMillis - startOfPeriod >= TimePeriod ) {
    // more time than TimePeriod has elapsed since last time if-condition was true
    startOfPeriod = currentMillis; // a new period starts right here so set new starttime
    return true;
  }
  else return false;            // actual TimePeriod is NOT yet over
}

void ManageSerialCommands() {

  if (myInputReader.read()) { // check if all characters of a command including delimiter are received
    if (myInputReader == "ON") {
      myStateVar = fsm_switchLEDOn;
    }

    if (myInputReader == "OFF") {
      myStateVar = fsm_SwitchLEDOFF;
    }
  }
}


void setup() {
  pinMode(LED_pin, OUTPUT); // no comment needed because of SELF-explaining name  led
  Serial.begin(115200);
  Serial.println( F("Setup-Start") );
  Serial.println( F("enter command ON or OFF to switch LED") );

  SafeString::setOutput(Serial); // enable error messages and SafeString.debug() output to be sent to Serial
  myInputReader.connect(Serial); // where SafeStringReader will read from in this demo the standard Serial
  myInputReader.echoOn(); // echo back all input, by default echo is off
  myStateVar = fsm_idling;
}


void FSM() {

  switch (myStateVar) {

    case fsm_idling:
      // just do sit and wait for serial commands
      break;

    case fsm_switchLEDOn:
      digitalWrite(LED_pin, HIGH);
      myWaitTimer = millis(); // initialise Timer-variable with actual value of millis()
      myStateVar = fsm_waitWithLEDOn;
      break;

    case fsm_waitWithLEDOn:
      if ( TimePeriodIsOver(myWaitTimer, LedOnTime) ) { // check if waitingtime is over
        // if number of milliseconds stored in LedOnTime have passed by
        Serial.println( F("waiting time over chnage to switching LED off") );
        myStateVar = fsm_SwitchLEDOFF;
      }
      break;

    case fsm_SwitchLEDOFF:
      digitalWrite(LED_pin, LOW);
      Serial.println( F("LED switched off") );
      Serial.println( F("enter command ON or OFF to switch LED") );
      myStateVar = fsm_idling;

    default:
      myStateVar = fsm_idling;
      break;
  }
}


void loop() {
  ManageSerialCommands();
  FSM();
}

best regards Stefan