Why does my Servo motor Jitter instead of holding position?

Question

I'm trying to control a servo using my Arduino, but I'm facing an issue where the servo jitters instead of holding its position. Even when I send a fixed angle using servo.write(), it moves slightly back and forth instead of staying still.

Here's my basic setup:

Arduino Uno
SG90 servo motor powered from the Arduino's 5V pin
Signal wire connected to pin 9

#include <Servo.h>

Servo myServo;

void setup() {
    myServo.attach(9);
    myServo.write(90); 
}

void loop() {
   
}

I've tried adding delay(1000); in the loop, but that didn't help. Do I need a separate power source for the servo, or is there another way to fix the jitter? Any advice would be greatly appreciated.

Admin · Answer

The jitter is most likely caused by power issues or signal noise. Since you're powering the SG90 servo from the Arduino's 5V pin, that might not provide enough current, leading to unstable movements. I've run into this before, and here’s what helped me fix it:

Quick Fixes:

Use an external 5V–6V power source for the servo instead of the Arduino’s 5V pin. Connect all GNDs together.
Add a 100µF capacitor across the servo’s VCC & GND to stabilize power.
Keep signal wires short to reduce interference.

If the issue persists, try this simple code to maintain position(let me know whether this works or not):

#include <Servo.h>
Servo myServo;
void setup() {
    myServo.attach(9);
}
void loop() {
    myServo.write(90);
    delay(20); // Helps stabilize position
}

One more thing, if you’re using a cheap SG90 clone, some jittering is just part of the deal.