SENSORS/ACTUATORS

ESP8266 - RFID - Servo Motor

This tutorial instructs you how to use an ESP8266 and RFID NFC RC522 module to control a servo motor. The process works as follows:

When an authorized tag is tapped, ESP8266 will rotate the servo motor to 90°
If the same tag is tapped again, the servo motor will be rotated back to 0°
This cycle will repeat indefinitely

This can be used to secure a cabinet, drawer, door, or control the pet feeder's opening and closing...

Hardware Preparation

1	×	ESP8266 NodeMCU
1	×	Micro USB Cable
1	×	RFID/NFC RC522 Kit (reader + tags)
1	×	RFID Key Fob
1	×	Servo Motor
1	×	5V 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

Disclosure: Some of the links provided in this section are Amazon affiliate links. We may receive a commission for any purchases made through these links at no additional cost to you. We appreciate your support.

Overview of RFID/NFC RC522 Module and Servo Motor

If you are unfamiliar with the RFID/NFC RC522 Module and Servo Motor (including pinout, functioning, and programming), check out the following tutorials:

ESP8266 - RFID/NFC RC522 tutorial
ESP8266 - Servo Motor tutorial

ESP8266 NodeMCU arduino rfid servo motor component

How It Works

Some UIDs of RFID/NFC tags are already programmed into the ESP8266 code.
When a user taps an RFID/NFC tag onto the RFID/NFC reader, the reader reads the UID from the tag.
The ESP8266 then receives the UID from the reader.
It compares the read UID with the predefined UIDs that were set in the code.
If the UID matches one of the predefined UIDs, the ESP8266 will control the servo motor to 90°.
When the tag is tapped again, the ESP8266 will control the servo motor back to 0°.
This process will repeat indefinitely.

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.

For the sake of simplicity, the above wiring diagram is utilized for testing or learning purposes, and for a small-torque servo motor. In actuality, we strongly suggest using an external power supply for the servo motor. The wiring diagram below illustrates how to connect the servo motor to an external power source.

The wiring diagram between ESP8266 NodeMCU and servo motor external power supply

This image is created using Fritzing. Click to enlarge image

※ NOTE THAT:

The arrangement of pins may differ depending on the manufacturer. ALWAYS use the labels printed on the module. The image above displays the pinout of modules from DIYables producer.

Wiring table of RFID/NFC RC522 Module

RFID/NFC RC522	ESP8266
SS	→ GPIO 5 (SPI CS/SS)
SCK	→ GPIO 8 (SPI CLK)
MOSI	→ GPIO 7 (SPI MOSI)
MISO	→ GPIO 6 (SPI MISO)
IRQ(not connected)
GND	→ GND
RST	→ TO_BE_UPDATED
VCC	→ 3.3V

ESP8266 Code - Single RFID/NFC Tag

/* * 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-rfid-servo-motor */ #include <SPI.h> #include <MFRC522.h> #include <Servo.h> #define SS_PIN D8 // The ESP8266 pin D8 #define RST_PIN D2 // The ESP8266 pin D2 #define SERVO_PIN D1 // The ESP8266 pin connects to servo motor MFRC522 rfid(SS_PIN, RST_PIN); Servo servo; byte authorizedUID[4] = {0xFF, 0xFF, 0xFF, 0xFF}; int angle = 0; // The current angle of servo motor void setup() { Serial.begin(9600); SPI.begin(); // init SPI bus rfid.PCD_Init(); // init MFRC522 servo.attach(SERVO_PIN); servo.write(angle); // rotate servo motor to 0° Serial.println("Tap RFID/NFC Tag on reader"); } void loop() { if (rfid.PICC_IsNewCardPresent()) { // new tag is available if (rfid.PICC_ReadCardSerial()) { // NUID has been readed MFRC522::PICC_Type piccType = rfid.PICC_GetType(rfid.uid.sak); if (rfid.uid.uidByte[0] == authorizedUID[0] && rfid.uid.uidByte[1] == authorizedUID[1] && rfid.uid.uidByte[2] == authorizedUID[2] && rfid.uid.uidByte[3] == authorizedUID[3] ) { Serial.println("Authorized Tag"); // change angle of servo motor if (angle == 0) angle = 90; else //if(angle == 90) angle = 0; // rotate the servo motor to the angle position servo.write(angle); Serial.print("Rotate Servo Motor to "); Serial.print(angle); Serial.println("°"); } else { Serial.print("Unauthorized Tag with UID:"); for (int i = 0; i < rfid.uid.size; i++) { Serial.print(rfid.uid.uidByte[i] < 0x10 ? " 0" : " "); Serial.print(rfid.uid.uidByte[i], HEX); } Serial.println(); } rfid.PICC_HaltA(); // halt PICC rfid.PCD_StopCrypto1(); // stop encryption on PCD } } }

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.
Click to the Libraries icon on the left bar of the Arduino IDE.
Search for “MFRC522” and locate the library by GithubCommunity.
Press the Install button to install the MFRC522 library.

In order to discover the UID of an RFID/NFC tag, the first step is to upload code to ESP8266 using the Arduino IDE and then click the Upload button. After that, open the Serial Monitor and tap the tag onto the RFID-RC522 module. The UID will be displayed on the Serial Monitor.

COM6

Send

Tap RFID/NFC tag on reader Unauthorized Tag with UID: 3A C9 6A CB

Autoscroll Show timestamp

Clear output

9600 baud

Newline

Once you have your UID:

Replace the UID in line 20 of the code with your own. For example, change byte authorizedUID[4] = {0xFF, 0xFF, 0xFF, 0xFF}; to byte authorizedUID[4] = {0x3A, 0xC9, 0x6A, 0xCB};
Upload the code to your ESP8266 board
Tap an RFID/NFC tag on the RFID-RC522 module
The servo motor should rotate to 90°
Check the output on the Serial Monitor

COM6

Send

Tap RFID/NFC tag on reader Authorized Tag Rotate Servo Motor to 90°

Autoscroll Show timestamp

Clear output

9600 baud

Newline

Tap the RFID/NFC tag on the RFID-RC522 module once more.
The servo motor will rotate to 0°, and you can observe this on the Serial Monitor.

COM6

Send

Tap RFID/NFC tag on reader Authorized Tag Rotate Servo Motor to 90° Authorized Tag Rotate Servo Motor to 0°

Autoscroll Show timestamp

Clear output

9600 baud

Newline

Tap an RFID/NFC tag to the RFID-RC522 module.
Check the Serial Monitor for the output.

COM6

Send

Tap RFID/NFC tag on reader Authorized Tag Rotate Servo Motor to 90° Authorized Tag Rotate Servo Motor to 0° Unauthorized Tag with UID: BD 1E 1D 00

Autoscroll Show timestamp

Clear output

9600 baud

Newline

ESP8266 Code - Multiple RFID/NFC Tags

We can enable multiple RFID/NFC tags to control a servo motor. As an example, the code below uses two tags.

/* * 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-rfid-servo-motor */ #include <SPI.h> #include <MFRC522.h> #include <Servo.h> #define SS_PIN D8 // The ESP8266 pin D8 #define RST_PIN D2 // The ESP8266 pin D2 #define SERVO_PIN D1 // The ESP8266 pin connects to servo motor MFRC522 rfid(SS_PIN, RST_PIN); Servo servo; byte authorizedUID1[4] = {0x3A, 0xC9, 0x6A, 0xCB}; byte authorizedUID2[4] = {0x30, 0x01, 0x8B, 0x15}; int angle = 0; // The current angle of servo motor void setup() { Serial.begin(9600); SPI.begin(); // init SPI bus rfid.PCD_Init(); // init MFRC522 servo.attach(SERVO_PIN); servo.write(angle); // rotate servo motor to 0° Serial.println("Tap RFID/NFC Tag on reader"); } void loop() { if (rfid.PICC_IsNewCardPresent()) { // new tag is available if (rfid.PICC_ReadCardSerial()) { // NUID has been readed MFRC522::PICC_Type piccType = rfid.PICC_GetType(rfid.uid.sak); if (rfid.uid.uidByte[0] == authorizedUID1[0] && rfid.uid.uidByte[1] == authorizedUID1[1] && rfid.uid.uidByte[2] == authorizedUID1[2] && rfid.uid.uidByte[3] == authorizedUID1[3] ) { Serial.println("Authorized Tag 1"); changeServo(); } else if (rfid.uid.uidByte[0] == authorizedUID2[0] && rfid.uid.uidByte[1] == authorizedUID2[1] && rfid.uid.uidByte[2] == authorizedUID2[2] && rfid.uid.uidByte[3] == authorizedUID2[3] ) { Serial.println("Authorized Tag 2"); changeServo(); } else { Serial.print("Unauthorized Tag with UID:"); for (int i = 0; i < rfid.uid.size; i++) { Serial.print(rfid.uid.uidByte[i] < 0x10 ? " 0" : " "); Serial.print(rfid.uid.uidByte[i], HEX); } Serial.println(); } rfid.PICC_HaltA(); // halt PICC rfid.PCD_StopCrypto1(); // stop encryption on PCD } } } void changeServo() { // change angle of servo motor if (angle == 0) angle = 90; else //if(angle == 90) angle = 0; // rotate the servo motor to the angle position servo.write(angle); Serial.print("Rotate Servo Motor to "); Serial.print(angle); Serial.println("°"); }

Repeat the same steps as before, and then tap each tag to the RFID-RC522 module. The output on the Serial Monitor should appear like this:

COM6

Send

Tap RFID/NFC tag on reader Authorized Tag 2 Rotate Servo Motor to 90° Authorized Tag 1 Rotate Servo Motor to 0°

Autoscroll Show timestamp

Clear output

9600 baud

Newline

You can expand the code written above to include three, four, or more tags.

Video Tutorial

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