Arduino - RFID/NFC
In this tutorial, we are going to learn how to use RFID/NFC with Arduino. The RFID/NFC system includes two components: reader and tag. There are two popular RFID/NFC readers: RC522 and PN532 RFID/NFC reader. This tutorial focuses on RC522 RFID/NFC reader. PN532 RFID/NFC reader will be presented in an upcoming tutorial.
RC522 RFID/NFC reader (also called RFID-RC522 Module) can:
- Read the UID of RFID/NFC tag
- Change the UID of RFID/NFC tag (only if the tag is UID-writable)
- Write data to RFID/NFC tag
- Read data from RFID/NFC tag
In above capabilities, for Arduino, reading the UID is the most widely-used. This tutorial focuses on reading the UID of RFID/NFC tag. The other will be present in next tutorials
|1||×||Arduino UNO or Genuino UNO|
|1||×||USB 2.0 cable type A/B|
|1||×||RFID/NFC RC522 Kit (reader + tags)|
About RFID-RC522 Module
RFID-RC522 Module Pinout
RFID-RC522 has 8 pins, some of them are common pins, the others are shared among three communication modes: SPI, I2C, UART. At a time, only one communication mode can be used. The pin are:
- GND pin: needs to be connected to GND (0V)
- VCC pin: needs to be connected to VCC (3.3)
- RST pin: is a pin for reset and power-down. When this pin goes low, hard power-down is enabled. On the rising edge, the module is reset.
- IRQ pin: is an interrupt pin that can alert the microcontroller when RFID tag comes into its vicinity.
- MISO/SCL/TX pin: acts as MISO when SPI interface is enabled, acts as SCL when I2C interface is enabled and acts as TX when UART interface is enabled.
- MOSI pin: acts as MOSI when SPI interface is enabled.
- SCK pin: acts as SCK when SPI interface is enabled
- SS/SDA/RX pin: acts as SS when SPI interface is enabled, acts as SDA when I2C interface is enabled and acts as RX when UART interface is enabled.
※ 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 module from DIYables manufacturer.
- Do not connect VCC pin to 5V pin. This will likely destroy your module.
- MFRC522 library supports only SPI mode. Therefore, this tutorial uses only SPI communication.
How RFID/NFC Works
RFID/NFC includes two components: reader and tag.
- The reader consists of a radio frequency module and an antenna which generates high frequency electromagnetic field.
- The tag is usually a passive device, which doesn’t need to have power source. The tag contains a microchip that stores and processes information, and an antenna to receive and transmit a signal. The tag is used to store the information: UID (Unique ID) and data.
To read the information on a tag, the tag must be in close proximity to the reader (does not require the direct line-of-sight). The reading processes:
- The reader generates an electromagnetic field which causes electrons to move through the tag’s antenna and subsequently power the chip.
- The chip inside the tag then responds by sending the requested information back to the reader in the form of another radio signal.
- The reader detects the signal and transform the signal into data
- Arduino reads the data from reader.
Wiring Diagram between RFID-RC522 Module and ESP32
Image is developed using Fritzing. Click to enlarge image
If you use the male-to-female jumper wires, you can connect Arduino UNO directly to RFID-RC522 module. If you use the male-to-male jumper wires, you need to connect Arduino UNO to RFID-RC522 module via a breadboard
Wiring table of RFID/NFC RC522 Module and Arduino
Arduino RFID/NFC Code
- On Arduino IDE, Go to Tools Manage Libraries
- Search “MFRC522”, then find the library by GithubCommunity
- Click Install button to install MFRC522 library.
- Copy the above code and open with Arduino IDE
- Click Upload button on Arduino IDE to upload code to Arduino
- Open Serial Monitor
- Tap several RFID/NFC tags on RFID-RC522 module
- See UID on Serial Monitor
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