Introduction: Ultrasonic Sensor Controlled Servo in NodeMCU

About: I am an electronic hobbyist on Arduino, Photon, Raspberry Pi and common electronics.A passionate cook.Any assistance in electronics and web development feel free to contact me at

Hi, I'm Sridhar Janardhan today I am teaching about how to interface ultrasonic sensor and control the servo motor based on the values thrown by the ultrasonic sensor.This ibles are for the node MCU beginners and I expect the peeps to stay patient to see the intermediate stage later weeks as soon I as finish the basic ibles of node MCU Arduino and photon.

Step 1:

Components required to do this projects are:

  • NodeMCU
  • Breadboard
  • Jumper wire
  • Ultrasonic sensor
  • Servo motor

Let's now start with the connection

Step 2: Ultrasonic Sensor Connection

Ultrasonic sensor are connected by the following instruction

  • Trig pin: This is connected to the digital pin 13
  • ECHO pin: This is connected to the digital pin 12
  • VCC pin: this is connected to the Positive railing of the breadboard
  • GND pin: this is connected to the negative railing of the breadboard

Step 3: Servo Connection

The servo motors are specially designed motor used to control the acceleration and angular rotation of the shaft.

The connection of the servo motor are as follows:

  • The red wire or positive supply is given to positive supply of the breadboard
  • The black wire or negative supply is given to the GND pin of the breadboard
  • The orange wire or signal wire is connected to the pin no 3 of node MCU

Step 4: Coding

const int trigPin = 15;
const int echoPin = 13;
long duration;
int distance;
int safetyDistance;
Servo myservo; // create servo object to control a servo // twelve servo objects can be created on most boards
int pos = 0; // variable to store the servo position
void setup() {
pinMode(trigPin, OUTPUT);
pinMode(echoPin, INPUT);
void loop() {
digitalWrite(trigPin, LOW);
digitalWrite(trigPin, HIGH);
digitalWrite(trigPin, LOW);
duration = pulseIn(echoPin, HIGH);
distance= duration*0.034/2;
safetyDistance = distance;
if (safetyDistance <= 5){
// goes from 0 degrees to 180 degrees // in steps of 1 degree
myservo.write(90); // tell servo to go to position in variable 'pos'
delay(15); // waits 15ms for the servo to reach the position
else{ // goes from 180 degrees to 0 degrees
myservo.write(0); // tell servo to go to position in variable 'pos'
delay(15); // waits 15ms for the servo to reach the position }
Serial.print("Distance: ");

Step 5: Output

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