LCD Unreliable

Using Arduino Programming Questions
#1

So In my project I am trying to rotate a servo using a angle counter then display this on an lcd screen. I have the buttons to move the servos and the LCD working. When I run the LCD example in the arduino ide it works perfectly but when I try to implement the LCD within my code it will work properly for a few seconds then everything goes haywire on the screen. I had problems with the numbers or text moving and printing in random locations while I reset the cursor every loop. And random characters also stream past the screen as well after awhile. So I am assuming there is something wrong with my code since the components seem to work individually but not in unison. I have tried to use lcd.clear() everyloop then set cursor but this also make the screen go crazy after a few seconds. If I don’t use the clear function the LCD will start putting numbers in the wrong location as I stated earlier.

Any help is appreciated

//Use poteniometer to vary plate angle with a serial read out of current angle. Use increments of 0.5 or 1 for largest values.
#include <Servo.h>
// include the library code:
#include <LiquidCrystal.h>
Servo myservo1;
Servo myservo2;  // create servo object to control a servo
// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(6, 7, 5, 4, 3, 2);
// twelve servo objects can be created on most boards
const int buttonPin1 = 8; 
const int buttonPin2 = 9; 
float pos = 0; 
float angle = 0; // variable to store the servo position
//pos goes from 0 to 90 convert to plate angle

void setup() {
  Serial.begin(9600);
   pinMode(buttonPin1, INPUT);
   pinMode(buttonPin2, INPUT);
  myservo1.attach(6);
  myservo2.attach(5);// attaches the servo on pin 9 to the servo object
   lcd.begin(16, 2);
}

void loop() {

// buttonstate1 = digitalRead(buttonPin1);
 //buttonstate2 = digitalRead(buttonPin2);

  // check if the pushbutton is pressed.
  // if it is, the buttonState is HIGH:
  if (digitalRead(buttonPin1) == HIGH) {
    // turn LED on:
   pos = pos+3;}
   else if (digitalRead(buttonPin2) == HIGH){
     pos = pos-3;
   }
pos=constrain(pos,0,90);
angle = mapfloat(pos,0,90,0,30);
    myservo1.write(pos); 
    myservo2.write(180-pos);// tell servo to go to position in variable 'pos'
     lcd.clear();
      lcd.setCursor(0, 0);
 lcd.print(angle);
//Serial.println(angle);
delay(100);

}
float mapfloat(long x, long in_min, long in_max, long out_min, long out_max)
{
 return (float)(x - in_min) * (out_max - out_min) / (float)(in_max - in_min) + out_min;
}

-Tyler Scofield
Research Aid

#2

It sounds like the power supply is not up to the job, or there is an electrical noise issue. Powering a servo from an Arduino can do this, but no wiring information was provided (and there is no information about the power supply or about the servo or about the Arduino) so I can do little to help except take guesses.

Also, these lines have misleading comments:

  myservo2.attach(5);// attaches the servo on pin 9 to the servo object


    // turn LED on:
   pos = pos+3;}


    myservo2.write(180-pos);// tell servo to go to position in variable 'pos'
#3 
LiquidCrystal lcd(6, 7, 5, 4, 3, 2);
myservo1.attach(6);
myservo2.attach(5);

Fix the pin conflict between the servos and the lcd.

#4

Good catch by cattledog!
(Wiring information would also catch this but was superfluous.)

#5

Ah yes I forgot about the wiring issues with the pins. Thanks guys.

#6