ESP32 - RFID - Solenoid Lock

In this tutorial, we are going to learn how to make RFID-based door lock system by using ESP32, RC522 RFID reader and solenoid lock.

Hardware Used In This Tutorial

1×ESP-WROOM-32 Dev Module
1×USB Cable Type-C
1×RFID/NFC RC522 Kit (reader + tags)
1×RFID Key Fob
1×Solenoid Lock
1×Relay
1×12V Power Adapter
1×DC Power Jack
1×(Recommended) ESP32 Screw Terminal Adapter

Or you can buy the following sensor kit:

1×DIYables Sensor Kit 30 types, 69 units
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Introduction to RFID/NFC RC522 Module and Solenoid Lock

Unfamiliar with RFID/NFC RC522 Module and solenoid lock, including their pinouts, functionality, and programming? Explore comprehensive tutorials on these topics below:

Wiring Diagram

ESP32 RFID RC522 solenoid lock wiring diagram

This image is created using Fritzing. Click to enlarge image

If you're unfamiliar with how to supply power to the ESP32 and other components, you can find guidance in the following tutorial: How to Power ESP32.

※ NOTE THAT:

The order of pins can vary according to manufacturers. ALWAYS use the labels printed on the module. The above image shows the pinout of the modules from DIYables manufacturer.

ESP32 Code - Single RFID Tag

/* * This ESP32 code is created by esp32io.com * * This ESP32 code is released in the public domain * * For more detail (instruction and wiring diagram), visit https://esp32io.com/tutorials/esp32-rfid-solenoid-lock */ #include <SPI.h> #include <MFRC522.h> #define SS_PIN 5 // ESP32 pin GPIO5 #define RST_PIN 27 // ESP32 pin GPIO27 #define RELAY_PIN 32 // ESP32 pin GPIO32 controls the solenoid lock via therelay MFRC522 rfid(SS_PIN, RST_PIN); byte authorizedUID[4] = {0xFF, 0xFF, 0xFF, 0xFF}; void setup() { Serial.begin(9600); SPI.begin(); // init SPI bus rfid.PCD_Init(); // init MFRC522 pinMode(RELAY_PIN, OUTPUT); // initialize pin as an output. digitalWrite(RELAY_PIN, LOW); // deactivate the solenoid lock => locked Serial.println("Tap RFID 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"); digitalWrite(RELAY_PIN, LOW); // deactivate the solenoid lock => unlocked delay(2000); digitalWrite(RELAY_PIN, HIGH); // activate the solenoid lock => locked } else { Serial.print("Unauthorized Tag:"); 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 } } }

Quick Instructions

  • If this is the first time you use ESP32, see how to setup environment for ESP32 on Arduino IDE.
  • Do the wiring as above image.
  • Connect the ESP32 board to your PC via a micro USB cable
  • Open Arduino IDE on your PC.
  • Select the right ESP32 board (e.g. ESP32 Dev Module) and COM port.

Because UID is usually not printed on RFID Tag, The first step we need to do is to find out the tag's UID. This can be done by:

  • Copy the above code and open with Arduino IDE
  • Click Upload button on Arduino IDE to upload code to ESP32
  • Open Serial Monitor
  • Tap an RFID Tag on RFID-RC522 module
  • Get UID on Serial Monitor
COM6
Send
Tap RFID Tag on reader Unauthorized Tag: 51 3D C1 AC
Autoscroll Show timestamp
Clear output
9600 baud  
Newline  

After having UID:

  • Update UID in the line 18 of the above code. For example, change byte authorizedUID[4] = {0xFF, 0xFF, 0xFF, 0xFF}; TO byte authorizedUID[4] = {0x51, 0x3D, 0xC1, 0xAC};
  • Upload the code to ESP32 again
  • Tap an RFID Tag on RFID-RC522 module
  • See output on Serial Monitor
COM6
Send
Tap RFID Tag on reader Authorized Tag
Autoscroll Show timestamp
Clear output
9600 baud  
Newline  
  • Tap another RFID Tag on RFID-RC522 module
  • See output on Serial Monitor
COM6
Send
Tap RFID Tag on reader Authorized Tag Unauthorized Tag: 5D 11 1A D3
Autoscroll Show timestamp
Clear output
9600 baud  
Newline  

ESP32 Code - Multiple RFID Tags

We can allow multiple RFID/NFC tags to activate the solenoid lock. The below code uses two tags as an example.

/* * This ESP32 code is created by esp32io.com * * This ESP32 code is released in the public domain * * For more detail (instruction and wiring diagram), visit https://esp32io.com/tutorials/esp32-rfid-solenoid-lock */ #include <SPI.h> #include <MFRC522.h> #define SS_PIN 5 // ESP32 pin GPIO5 #define RST_PIN 27 // ESP32 pin GPIO27 #define RELAY_PIN 32 // ESP32 pin GPIO32 controls the solenoid lock via therelay MFRC522 rfid(SS_PIN, RST_PIN); byte authorizedUID1[4] = {0x51, 0x3D, 0xC1, 0xAC}; byte authorizedUID2[4] = {0x30, 0x01, 0x8B, 0x15}; void setup() { Serial.begin(9600); SPI.begin(); // init SPI bus rfid.PCD_Init(); // init MFRC522 pinMode(RELAY_PIN, OUTPUT); // initialize pin as an output. digitalWrite(RELAY_PIN, LOW); // deactivate the solenoid lock => locked Serial.println("Tap RFID 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"); digitalWrite(RELAY_PIN, LOW); // deactivate the solenoid lock => unlocked delay(2000); digitalWrite(RELAY_PIN, HIGH); // activate the solenoid lock => locked } 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"); digitalWrite(RELAY_PIN, LOW); // deactivate the solenoid lock => unlocked delay(2000); digitalWrite(RELAY_PIN, HIGH); // activate the solenoid lock => locked } else { Serial.print("Unauthorized Tag:"); 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 } } }

Do the similar steps as the above, and then tap one by one tag on RFID-RC522 module. The result on Serial Monitor looks like below:

COM6
Send
Tap RFID Tag on reader Authorized Tag 2 Authorized Tag 1
Autoscroll Show timestamp
Clear output
9600 baud  
Newline  

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