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Topic: Automatic Servo with Manual Override (delay problems) (Read 2 times) previous topic - next topic

landis

Hello I am new to the forum, I couldn't find any thread that delt with these problems as a whole, and they act very differently when they are put together in one program.

I have a design expo on saturday and I am in some urgent help.

BACKGROUND:
I am building a camera mechanism that is automatically panning and controlled by a two button controlled servo. I want this device to automatically pan to 180 and back to 0 continuously until a button is pressed. Once a button is pressed(left or right) I want the servo to pan in the coinciding direction. Then i want the position of the servo to stop if the button was not pressed anymore, and then after a certain amount of time, have the automatic panning start back up.

OVERVIEW:
My code is in a case structure format. Case 0 is the automatic panning to the right, Case 1 is the automatic panning to the left. During both of these cases the code looks to see if any of the buttons are being pressed If they arent, they switch between each other, if a button is being pressed then the code changes the casenumber and breaks the loop.

Case 2 is for when the leftbutton is pressed and it pans left for that amount of time, Case 3 is the same thing but for the right button. In both of these cases I am looking to see when the button stops being pressed. If it is the servo should stay in its current position for some arbitrary time. I made an if statement that test to see whether the
"current time" - the "previous time" is greater than the interval and if it is it should break to the automatic.

However, my code seems to think this is always true and immediately breaks out of the loop, essentially making not delay

CODE:
Here's my code,
fast help is greatly appreciated
Code: [Select]
#include <Servo.h>

Servo myservo;
const int leftbutton = 2;  //variable to represent the pin that the left button is on
const int rightbutton = 4;  //variable to represent the pin that the right button is on
int casenum = 0;  //case number to tell the servo which case to run
int pos = 0;  //position
int delaytime = 20;  // increasing this slows down the servo movement
unsigned long previousmillis = 0; // last time update
int interval = 2000; // interval at which to do something (milliseconds)

void setup()
{   
 
 
  myservo.attach(9);  // attaches the servo on pin 9 to the servo object
 
  pinMode(leftbutton, INPUT);  // the buttons are the inputs
  pinMode(rightbutton, INPUT);

}

void loop()
{
  unsigned long currentmillis = millis();
  if (digitalRead(leftbutton))  //checks to see if each button is being pressed
        {
          casenum = 2;  //if so it switches the casenum
        }
        if (digitalRead(rightbutton))
        {
          casenum = 3;
        }
 
  switch (casenum)  //switch switches the case based on the value of casenum
  {
    case 0:
    for (pos = pos; pos < 180; pos += 1)  // pan right
      {
       
        myservo.write(pos);  // Move to next position
        delay(delaytime);  // Short pause to allow it to move
        if (digitalRead(leftbutton))  //checks to see if each button is being pressed
        {
          casenum = 2;  //if so it switches the casenum
          break;
        }
        if (digitalRead(rightbutton))
        {
          casenum = 3;
          break;
        }
      }

    casenum = 1;  //if none of the buttons are pressed then it goes to pan left
    break;
   
    case 1:
    for(pos = pos; pos >= 0; pos -= 1)  // pan left
      {
     
        myservo.write(pos);  // Move to next position
        delay(delaytime);  // Short pause to allow it to move
        if (digitalRead(leftbutton))  //checks to see if each button is being pressed
        {
          casenum = 2;  //if so it switches the casenum
          break;
        }
        if (digitalRead(rightbutton))
        {
          casenum = 3;
          break;
        }
       
      }
    casenum = 0;
    break;

    case 2:
    while (digitalRead(leftbutton))  //while the button is being pressed
    {
        myservo.write(pos);  //rotates servo to its current positon
        delay(delaytime);
        pos-=1;  //position becomes one less
    }
        myservo.write(pos);  //after the button stops being pressed the servo is at pos
        if(currentmillis - previousmillis >= interval)  //if the total time - the start time is greater than 3 sec
        {         
          casenum = 1;                //this is where the code goes wrong, it seems like it reads this if statement
                                      //and immedietly say thinks its true
          previousmillis = currentmillis;
          break;
        }
        if (digitalRead(rightbutton))
        {
        casenum = 3;
        break;
        }
        if (digitalRead(leftbutton))
        {
          casenum = 2;
          break;
        }
     
     
    case 3:
    while (digitalRead(rightbutton))
        {
          myservo.write(pos);
          delay(delaytime);
          pos +=1;
        }
        myservo.write(pos);
        if(currentmillis - previousmillis >= interval)  //if the total time - the start time is greater than 3 sec
        {         
          casenum = 1;  //this is where the code goes wrong, it seems like it reads this if statement
                        //and immedietly say thinks its true
          previousmillis = currentmillis;
          break;
        }
        if (digitalRead(rightbutton))
        {
          casenum = 3;
          break;
        }
        if (digitalRead(rightbutton))
        {
          casenum = 2;
          break;
        }

        default:
        casenum = 0;
        break;
  } 
}


landis

This problem is in Case 2 & 3, sorry for not mentioning

Arrch

Your problem is that you are only ever setting previousMillis in the beginning of the code and when the 3 seconds have been reached, so rather than measuring the time since the button was released, you're measuring the time since the start of the program the first time, and the time since you went back to your automatic mode each subsequent time. I would change the name of previousMillis to lastTimeButtonWasPressed. That should give you a better idea of where you should be updating it.

landis

I understand that I am setting previousmillis in the beginning to 0. however isn't it changing in my loops when I say previousmillis = currentmillis


And can you elaborate on the lastTimeButtonWasPressed, I think I might get what your saying but its cloudy

Arrch


however isn't it changing in my loops when I say previousmillis = currentmillis

Because you only ever set it when you say "the button has been released long enough for me to go back to state 0 and state 1".

Quote

And can you elaborate on the lastTimeButtonWasPressed, I think I might get what your saying but its cloudy


In how you want it to work, previousMillis should be set based on the state of the button (or more specifically, you want it to be set on the transition). As it stands now, there is no link between when previousMillis is set and the state of the button. I suggested changing the name to show that they should be related, as well as give you a hint on where it should be being set.

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