Random movement via, Millis

Projects Programming
1

I'm trying to understand how to incorporate A random statement into a Millis function I have set up for random sounds to add a motor movement.

I have a motor where I am using a tb6612fng, to rotate a motor on my robot. In my sketch I use the Millis function to have a random sound play via a DFplayermini every min, and I want that to correspond with a head movement. perhaps using something like:

randomSeed( analogRead(A0) );

(trying to Keep it truly random)

After I added the movement into the statement, I realize its to structured and I'd like to to do one of maybe a few pre-programed movements.

can someone help explain to be a good way and how I would set-up a group of set movements and use random within the millis statement to call upon one of these?

example of the Motor statements I'd like to be random:

//Movement one:
  motor1.drive(255,200);
  motor1.drive(-255,200);

  //Movement two:
  motor1.drive(-255,200);
  motor1.drive(255,200);

My millis statement I'd like the random movement to happen within:

const unsigned long eventInterval = 60000; // 90000= 1.5 min change value to change chatter time
unsigned long previousTime = 0;
int randomInt;


unsigned long currentTime = millis();

  if ( currentTime - previousTime >= eventInterval) { // delay event for R2s "chatter" sounds folder 01

  randomInt = random(1, 144);  //number of tracks in folder on Sd card
  myMP3.playFolder(1, randomInt); //Plays random track from dfplayer
  previousTime = currentTime;
  }
2

I would write a function that you can call from loop(). I'm not sure how well the below combines with your MP3; if that is blocking, it will probably not work that well. I think it's self documenting.

void loop()
{
  moveIt();

  // MP3 stuff here
  ...
  ...
}


void moveIt()
{
  // variables that will be remembered

  // last time that a movement is done
  static unsigned long lastUpdateTime;
  // desired random interval
  static unsigned long interval;
  // which move to do
  static byte moveSelect = 0;

  // if it's time
  if (millis() - lastUpdateTime >= interval)
  {
    // do the move
    switch (moveSelect)
    {
      case 0:
        //Movement one:
        motor1.drive(255, 200);
        motor1.drive(-255, 200);
        break;
      case 1:
        //Movement two:
        motor1.drive(-255, 200);
        motor1.drive(255, 200);
        break;
    }

    // set a new interval between 1 and 2 seconds
    interval = random(1000, 2000);
    // remember when the movement was done last
    lastUpdateTime = millis();

    // indicate which movement next
    moveSelect++;
    if (moveSelect == 2)
    {
      moveSelect = 0;
    }
  }
}

If you have more than a few movements, the switch statement will become big. In that case you're better of using arrays and using moveSelect as an index.

Note:
The use of static variables allows the function to be stand-alone without dependencies on global variables. Motor1 is still a global variable though.