Arduino waits until button release to activate

Question

I'm fairly new to arduino, and on my own I'm trying to move a servo to the left and right using 2 buttons. I've got it working for the most part, however when I hold the button down nothing happens, and when I finally release the servo moves a certain amount based on how long I was holding the button down. I would like the servo to move when the button is being held down though. The servo also occasionally moves oddly and sporadically. I'm thinking its most likely a logic error in the code, but I can't figure it out. Could someone please tell me what they think I've done wrong? Thank you.

code:

#include <Servo.h>
Servo servo;

#define right 9
#define left 8

int angle = 90;
int angStep = 5;



void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  pinMode(right, INPUT_PULLUP);
  pinMode(left, INPUT_PULLUP);
  servo.attach(2);
  servo.write(angle);
  Serial.print("Begin");
  Serial.print('\n');
  Serial.print(angle);
  Serial.print(angle);
}

void loop() {
  // put your main code here, to run repeatedly:
  if (digitalRead(left) == HIGH && angle < 180){
    angle += angStep;
    Serial.print(angle);
    Serial.print('\n');
    servo.write(angle);
    delay(50);
  }

  if (digitalRead(right) == HIGH && angle > 0){
    angle -= angStep;
    Serial.print(angle);
    Serial.print('\n');
    servo.write(angle);
    delay(50);
  }
}

Answer 1

I think it's because you are using a pullup resistor, so it's constantly HIGH instead of constantly LOW. Try changing HIGH and LOW to the opposite.