Problem with servo

[mrcubez_96]

I'm trying out a servo motor for the first time. I want it to turn 0 degree when 'on' is entered and 90 degree when 'off' is entered. But it shows random stuff in the serial monitor and sometimes it just stops working. I don't know whether it's a problem with the code or with the servo. I'm providing a 5V power supply from the arduino UNO.

#include <Servo.h>

Servo servoMotor;
int servoPin = 9;

void setup() {
  Serial.begin(9600);
  servoMotor.attach(servoPin);
  servoMotor.write(90);
}

void loop() {
  if (Serial.available() > 0) {
    String state = Serial.readString();
    state.trim();
    if(state == "on"){
      servoMotor.write(0);
    }
    else if (state == "off"){
      servoMotor.write(90);
    }
    else{
      Serial.println("Invalid Input");
    }
  }
}

[UKHeliBob]

What have you got Line Ending set to in the Serial monitor ?

How is the servo powered and which Arduino are you using ?

[jim-p]

@mrcubez_96

I'm providing a 5V power supply from the arduino UNO.

You need to connect the servo to a 5V power supply, NOT the UNO 5V output

[mrcubez_96]

oh, so i'll need a separate power supply? the 5V on the arduino won't work?

[jim-p]

It can't output enough current for even a small servo.
If you don't have a 5V supply, you can use 4 AA batteries

[mrcubez_96]

ok, thx! i'll surely try it

[jim-p]

Make sure you connect the servo ground wire (usually black) to BOTH the power supply and the UNO GND

[UKHeliBob]

Don't forget to connect the GND of the external supply to the GND of the Uno so that there is a common point of reference for the servo control signal

As an aside, it is an unfortunate fact that a Uno can provide enough current to drive a servo, but only under very limited circumstances. The Uno is not designed to be used as a power supply

[jim-p]