SENSORS/ACTUATORS

ESP8266 - Light Sensor LED

This tutorial instructs you how to use ESP8266 and light sensor to trigger LED. In detail:

When the reading value from the light sensor is lower than a certain threshold, ESP8266 turns the LED on.
When the reading value from the light sensor is greater than a certain threshold, ESP8266 turns the LED off.

The light sensor is also known as photoresistor, light-dependent resistor, photocell, LDR. The ESP8266 utilizes a light sensor to measure the ambient light level. If the environment is dim, the ESP8266 turns on the LED, and if it's bright, the LED will be turned off.

Hardware Preparation

1	×	ESP8266 NodeMCU
1	×	Micro USB Cable
1	×	Light Sensor
1	×	LED
1	×	220 ohm resistor
1	×	10 kΩ resistor
1	×	Breadboard
1	×	Jumper Wires
1	×	(Optional) 5V Power Adapter for ESP8266
1	×	(Optional) ESP8266 Screw Terminal Adapter

Or you can buy the following sensor kit:

DIYables Sensor Kit 30 types, 69 units

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Overview of LED and Light Sensor

If you are unfamiliar with LED and light sensor (including pinout, how it works, and how to program), the following tutorials can help:

Wiring Diagram

This image is created using Fritzing. Click to enlarge image

See more in ESP8266's pinout and how to supply power to the ESP8266 and other components.

ESP8266 Code

/* * This ESP8266 NodeMCU code was developed by newbiely.com * * This ESP8266 NodeMCU code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * https://newbiely.com/tutorials/esp8266/esp8266-light-sensor-led */ #define LIGHT_SENSOR_PIN A0 // The ESP8266 pin connected to light sensor #define LED_PIN D8 // The ESP8266 pin connected to LED #define ANALOG_THRESHOLD 500 void setup() { pinMode(LED_PIN, OUTPUT); // Configure the ESP8266 pin to the output mode } void loop() { int analog_value = analogRead(LIGHT_SENSOR_PIN); // read the value on analog pin if (analog_value < ANALOG_THRESHOLD) digitalWrite(LED_PIN, HIGH); // turn on LED else digitalWrite(LED_PIN, LOW); // turn off LED }

Detailed Instructions

To get started with ESP8266 on Arduino IDE, follow these steps:

Check out the how to setup environment for ESP8266 on Arduino IDE tutorial if this is your first time using ESP8266.
Wire the components as shown in the diagram.
Connect the ESP8266 board to your computer using a USB cable.
Open Arduino IDE on your computer.
Choose the correct ESP8266 board, such as (e.g. NodeMCU 1.0 (ESP-12E Module)), and its respective COM port.
Plug the USB cable into the ESP8266 and the PC.
Launch the Arduino IDE, choose the correct board and port.
Copy the code and open it in the Arduino IDE.
Click the Upload button in the Arduino IDE to compile and upload the code to the ESP8266.

Emit light source towards the sensor
Check out the LED's state

Code Explanation

Check out the line-by-line explanation contained in the comments of the source code!

Video Tutorial

Learn More

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