ESP8266 - Potentiometer Relay

This tutorial instructs you how to use ESP8266 and potentiometer to control relay. In detail:

ESP8266 checks if the potentiometer's analog value is higher or lower than a threshold and act accordingly - turning the relay on or off
ESP8266 checks if the potentiometer's output voltage is above or below a threshold and act accordingly - turning the relay on or off

By attaching a relay to a light bulb, LED strip, motor, or actuator.. We can then use the ESP8266 and potentiometer to control the light bulb, LED strip, motor, or actuator...

Hardware Preparation

1	×	ESP8266 NodeMCU
1	×	Micro USB Cable
1	×	Potentiometer
1	×	Relay
1	×	Warning Light Bright Waterproof
1	×	12V Power Adapter
1	×	DC Power Jack
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 Relay and Potentiometer

If you are unfamiliar with relay and potentiometer (including pinout, functionality, and programming), 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 - Analog Threshold

/* * 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-potentiometer-relay */ #define POTENTIOMETER_PIN A0 // The ESP8266 pin connected to Potentiometer pin #define RELAY_PIN D8 // The ESP8266 pin connected to Relay's pin #define ANALOG_THRESHOLD 1000 void setup() { pinMode(RELAY_PIN, OUTPUT); // Configure the ESP8266 pin to the output mode } void loop() { int analog_value = analogRead(POTENTIOMETER_PIN); // read the input on analog pin if (analog_value > ANALOG_THRESHOLD) digitalWrite(RELAY_PIN, HIGH); // turn on Relay else digitalWrite(RELAY_PIN, LOW); // turn off Relay }

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.
Connect your ESP8266 to the computer using a USB cable.
Launch the Arduino IDE, select the correct board and port.
Copy the code above and open it in the Arduino IDE.
Click the Upload button in the Arduino IDE to compile and upload the code to the ESP8266.

Turn the potentiometer
Check out the alteration in the relay's condition

Code Explanation

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

ESP8266 Code - Voltage Threshold

The analog value of a potentiometer is changed to a voltage value. This voltage is then compared to a voltage threshold, which causes the relay to be triggered.

/* * 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-potentiometer-relay */ #define POTENTIOMETER_PIN A0 // The ESP8266 pin connected to Potentiometer pin #define RELAY_PIN D8 // The ESP8266 pin connected to Relay's pin #define VOLTAGE_THRESHOLD 2.5 // Voltages void setup() { pinMode(RELAY_PIN, OUTPUT); // Configure the ESP8266 pin to the output mode } void loop() { int analog_value = analogRead(POTENTIOMETER_PIN); // read the input on analog pin float voltage = floatMap(analog_value, 0, 1023, 0, 5); // Rescale to potentiometer's voltage if(voltage > VOLTAGE_THRESHOLD) digitalWrite(RELAY_PIN, HIGH); // turn on Relay else digitalWrite(RELAY_PIN, LOW); // turn off Relay } float floatMap(float x, float in_min, float in_max, float out_min, float out_max) { return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min; }

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