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Arduino Forum HELP! - Arduino code isn't working!
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Related

HELP! - Arduino code isn't working!

braedan
braedan over 9 years ago

Hello!

I have my arduino uno hooked up to a L293D dual h-bridge with an LED on each out put. So if the positive voltage goes out one terminal, one of the LEDs will light up to indicate the motor will be turning in that direction. Again there is not motor currently wired into it, and i have confirmed that this system works, no circuit problems here! I'm trying to create a simple closed loop feed back system to control to control a geared dc motor like a servo by attaching a potentiometer (variable resistor) to the end of the motor shaft to give the arduino some data to work with. In this testing stage in addition to the two LEDs hooked up to the h-bridge a pot-meter by itself is being used so i can mimic the rotation of the motors shaft with out a motor. My problem is when I start my arduino (with the pot-meter off the target value) the led lights up (good so far), but when i turn the meter past it it stays on. It flickers when the value is in range but never turns the other direction.

 

my code:

int enablepin = 9;
int mpin1 = 6;
int mpin2 = 3;


int desiredpos;
int ifint;


int feedbackpin = A5;
int mindegrees = 0;
int maxdegrees = 180;
int minfeedback = 40;;
int maxfeedback = 980;
int tolerance = 2;


int getPos(int analogPinn)
{
  return map(analogRead(analogPinn), minfeedback, maxfeedback, mindegrees, maxdegrees);
}


void Seek(int left_pin, int right_pin, int analogPin, int pos, int Speed)
{
  int currentpos = getPos(analogPin);
  Serial.println(currentpos);
  int currentpin;
  int target = map(pos, mindegrees, maxdegrees, minfeedback, maxfeedback);
  
  if(currentpos < target)
  {
    if (target < 90)
    {
      currentpin = right_pin;
    }
    if (target > 90)
    {
      currentpin = left_pin;
    }
  }
  if(currentpos > target)
  {
    if (target > 90)
    {
      currentpin = right_pin;
    }
    if (target < 90)
    {
      currentpin = left_pin;
    }
  }


  analogWrite(currentpin, Speed);


  while(abs(analogRead(analogPin) - target) > tolerance){}


  analogWrite(currentpin, 0);
}


void setup() {
  Serial.begin(9600);
  Serial.print("");
  pinMode(enablepin, OUTPUT);
  pinMode(mpin1, OUTPUT);
  pinMode(mpin2, OUTPUT);
  digitalWrite(enablepin, HIGH);
  digitalWrite(mpin1, LOW);
  digitalWrite(mpin2, LOW);
  desiredpos = 50;
  //Seek(mpin1, mpin2, feedbackpin, 50, 5);
}


void loop() {
  ifint = (getPos - desiredpos);
  if (ifint > tolerance)
  {
     Seek(mpin1, mpin2, feedbackpin, desiredpos, 5);
  }
  
}

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  • kulky64
    kulky64 over 9 years ago

    Your program has bunch of errors:

    1. As Mark mentioned on line 80 you are calling getPos without any perameter (does that even compile?). It should be something like this:

    ifint = (getPos(feedbackpin) - desiredpos);

    2. On line 81 you should calculate absolute value of ifint, this is why your program reacts only in one directon. Say for example you have your pot in 20 degrees position and your desired position is 50 deg, then

    ifint = 20 - 50 = -30

    and condition if (-30 > 2) is FALSE and nothing will happen.

    3. You have mismatch in your units. In function getPos you are mapping analog value of your pot position from range (40; 980) to range (0; 180). But on line 29 you are mapping target value in the opposite direction - from (0; 180) to (40; 980). Then you compare variables currentpos and target in incompatible ranges. Choose one unit a do all your work in this unit.

    4. Didn't quite understand the logic behind these conditions:

    if (target < 90)

    {

       currentpin = right_pin;

    }

    if (target > 90)

    {

       currentpin = left_pin;

    }

    Why are you comparing target against 90? Not to mention your target variable IS NOT in degrees (see point 3).

    5. You are generating PWM on certain pin, but you doesn't care what happens with your other pin. If you generate PWM on one pin, the other pin should be writen to 0 and vice versa.

    6. While loop on line 58 - see point 3.

    7. You are controlling your motor with ON-OFF control. I would implement at least P regulator.

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  • braedan
    braedan over 9 years ago in reply to kulky64

    Thank you for your help! I got it to work flawlessly with several major tweaks.

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  • braedan
    braedan over 9 years ago in reply to kulky64

    Thank you for your help! I got it to work flawlessly with several major tweaks.

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