Using millis() outside the loop() (in a function called by a function)

After spending some time searching the internet and finding nothing, I decided to use the forum.

I’m trying to make the following work: I want to use the Serial Monitor to send a message to the Arduino, to which it should react. In that reaction, I would like to use a timer (with millis() ). The problem I seem to have is that my function is only called once, of that the timer does not work, I don’t not. I’m new to the millis()-function, but this is the first time I couldn’t fix the problem myself …

If there is another way to do what I want to do, which is, simply put, making my led blink once after typing something in to the serial monitor, please do tell.

(my project is more complicated than the example, the LED is an RGB-strip, but I think this is easier to use on the forum).

Any tips are welcome!

My code (for now):

int blinkTime = 1000;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
  pinMode(13, OUTPUT);
  if (Serial.available() > 0) {
    testSerial(Serial.readString());
  }
}


void testSerial(String test) {
  if (test.equals("1")) Serial.println("1 ingegeven");
  else if (test.equals("2")) Serial.println("2 ingegeven");
  else if (test.equals("3")) blinkLedOnce();

}

void blinkLedOnce() {
  Serial.println("BlinkTest begonnen");

  unsigned long currentMillis = millis();
  while (currentMillis <= 2 * blinkTime + 1) {
    digitalWrite(13, LOW);
    if (currentMillis >= blinkTime && currentMillis < 2 * blinkTime) digitalWrite(13, HIGH);
    else if (currentMillis >= 2 * blinkTime) digitalWrite(13, LOW);
  }
  Serial.println("BlinkTest gestopt");
}

Always show us the whole sketch.

Maybe this example will help with your BWD programming.

//Blink without Delay skeleton 
//4 examples demonstrated
//

//LED wiring options
//=============================================
//Depending which way your LEDs are wired, uncomment the next line.
//#define PlusEqualsON 

#ifdef PlusEqualsON
//wired so +5V turns LED ON
#define ledON  HIGH
#define ledOFF LOW
//=========================
#else
//wired so +5V turns LED OFF
#define ledON  LOW
#define ledOFF HIGH
//=========================
#endif

//switch wiring options
//=============================================
//Depending which way your switches are wired, uncomment the next line.
#define PushEqualsLOW 

#ifdef PushEqualsLOW 
//pushing the switch makes pin LOW
#define Pushed   LOW
#define Released HIGH
//=========================
#else
//pushing the switch makes pin HIGH
#define Pushed   HIGH
#define Released LOW
//=========================
#endif

//=============================================
unsigned long currentMillis;
unsigned long pin13Millis;
unsigned long pin12Millis;
unsigned long pin11Millis;
unsigned long SwitchMillis;

//if these are not changed in the sketch, they can be const
unsigned long debounceMillis = 100UL;     //100ms
unsigned long ledOnTime      = 5*1000UL;  //5 seconds

byte laststartSwitchState    = HIGH;
byte buttonState             = HIGH;
byte counter                 = 0;

//the following are enable/disable flags
//some of these might not be used in this sketch
boolean flag13 = true;
boolean flag12 = true;
boolean flag11 = true;
boolean flag10 = true;

const byte startSwitch = 2; //pushed = LOW
const byte testSwitch  = 3; //pushed = LOW

//**********************************************************************

void setup()
{
  Serial.begin(9600);
  
  digitalWrite(13,ledOFF);
  pinMode(13, OUTPUT); 

  digitalWrite(12,ledOFF);
  pinMode(12, OUTPUT);

  digitalWrite(11,ledOFF);
  pinMode(11, OUTPUT);
  
  digitalWrite(10,ledOFF);
  pinMode(10, OUTPUT);

  pinMode(startSwitch, INPUT_PULLUP); //pushed = LOW
  pinMode(testSwitch,  INPUT_PULLUP); //pushed = LOW

} //  >>>>>>>>>>>>>> E N D  O F  s e t u p ( ) <<<<<<<<<<<<<<<<<

void loop()
{
  //save the current time
  currentMillis = millis();

  //************************************* E x a m p l e  1
  //toggle pin 13 every 200mS
  //has 200ms or more gone by?
  if (currentMillis - pin13Millis >= 200UL)
  {
    //code here runs every 200ms
    //get ready for next iteration
    pin13Millis = pin13Millis + 200UL;
    //toggle pin 13
    digitalWrite(13,!digitalRead(13));
  }

  //************************************* E x a m p l e  2
  //at power up, pin 12 LED goes ON, after 3 seconds goes OFF and stays OFF
  //could be used as a powerup reset signal
  if (flag12 == true && currentMillis - pin12Millis <= 3000UL)
  {
    //code here runs for 3 seconds after power up, then stops
    digitalWrite(12,ledON);
  }
  else
  {
    digitalWrite(12,ledOFF);
    //disable further pin 12 control
    flag12 = false;
  }

  //************************************* E x a m p l e  3
  //if testSwitch is pushed and released
  //pin 11 LED goes ON for 5 seconds, then goes OFF 
  buttonState = digitalRead(testSwitch);
  
  //are we are allowed to check the switch and is it pressed?
  if(flag11 == true && buttonState == Pushed)
  {    
    //enable timing of LED on pin 11
    flag11 = false; //false --> timing is enabled
    //turn LED ON
    digitalWrite(11,ledON);
    //record the time LED turned ON
    pin11Millis = currentMillis;
  }
    
  //are we allowed and is it time to control pin 11
  if (flag11 == false && currentMillis - pin11Millis >= ledOnTime)
  {
    //if enabled, code here runs after ledOnTime ms goes by
    digitalWrite(11,ledOFF);
    //allow switch press detection again
    flag11 = true; //true --> switch monitoring is enabled
  }

  //************************************* E x a m p l e  4
  //is it time to check the switches?
  //in particular, pushing startSwitch will turn ON/OFF (toggle) an output pin 10
  //is it time to check the switches
  if (currentMillis - SwitchMillis >= debounceMillis)
  {
    //code here runs every debounceMillis ms
    //get ready for the next iteration
    SwitchMillis += debounceMillis; 
    //go and check the switches
    checkSwitches();    
  } 

  //*********************************
  //put other non-blocking stuff here
  //*********************************

} //  >>>>>>>>>>>>>> E N D  O F  l o o p ( ) <<<<<<<<<<<<<<<<<


//======================================================================
//                      F U N C T I O N S
//======================================================================


//****************** c h e c k S w i t c h e s ( ) *********************
//switches are checked every debounceValue milli seconds 
//no minimum switch press time is validated with this code (i.e. No glitch filter)
void checkSwitches()  
{
  //re-usable for all the switches  
  boolean thisState;    

  //************************************* E x a m p l e  Push ON push OFF (toggle)   
  //check if this switch has changed state
  thisState = digitalRead(startSwitch);
  if (thisState != laststartSwitchState)
  {  
    //update the switch state
    laststartSwitchState = thisState;  

    //this switch position has changed so do some stuff

    //"HIGH condition code"
    //switch went from LOW to HIGH
    if(thisState == HIGH)        
    {
      //Do some HIGH switch stuff here
    }

    //"LOW condition code"
    //switch went from HIGH to LOW
    else                          
    {
      //Do some LOW switch stuff here  
      digitalWrite(10, !digitalRead(10));
      //print number of pushes
      counter++;
      Serial.println(counter);
    }

  } //END of startSwitch code

  //*****************************************  
  //similar code for other switches goes here 
  //*****************************************  

} //END of checkSwitches()

//**********************************************************************

//======================================================================
//                      E N D  O F  C O D E
//======================================================================

Pouckie:

  else if (test.equals("3")) blinkLedOnce();

Rather than call the blinkLedOnce() here you should just change a variable - for example

   else if (test.equals("3")) {
       blinkOn = true;
       blinkStartMillis = millis()
    }

and then call the function blinkLedOnce() from loop() and modify it something like this

void blinkLedOnce() {
  if (blinkOn == true) {
     Serial.println("BlinkTest begonnen");
     digitalWrite(13, HIGH);
     if (millis() - blinkStartMills >= blinkLengthMillis) {
          digitalWrite(13, LOW);
          blinkOn = false;
          Serial.println("BlinkTest gestopt");
     } 
  }
}

...R

@ LarryD: My whole sketch is 317 lines. I always try to break-up the code until a new piece works before I put it all together. The only thing I’m going to change is the “digitalWrite(13, LOW);” command to “ledStateRood = 255;” or something like that.

@ Robin2: works like a charm! Calling the function from inside the loop() like that fixed my problem, thanks! And thanks for the quick response, I didn’t expect to have an answer so soon.

The resulting code is (for those interested):

int blinkLengthMillis = 1000;
unsigned long blinkStartMillis = 0;
boolean blinkOn = false;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
  pinMode(13, OUTPUT);
  blinkLedOnce();
  if (Serial.available() > 0) {
    testSerial(Serial.readString());
  }
}


void testSerial(String test) {
  if (test.equals("1")) Serial.println("1 ingegeven");
  else if (test.equals("2")) Serial.println("2 ingegeven");
  else if (test.equals("3")) {
       blinkOn = true;
       blinkStartMillis = millis();
    }

}

void blinkLedOnce() {
  if (blinkOn == true) {
     Serial.println("BlinkTest begonnen");
     
     digitalWrite(13, HIGH);
     if (millis() - blinkStartMillis >= blinkLengthMillis) {
          digitalWrite(13, LOW);
          blinkOn = false;
          Serial.println("BlinkTest gestopt");
     } 
  }
}

Glad it is working.

I should have included these two links showing a more general use of the technique
Several Things at a Time
Planning and Implementing a Program

...R