RFID RC522 Module Symbol
Definition: The RFID RC522 Module symbol represents a 13.56 MHz MFRC522-based Radio Frequency Identification reader/writer module — interfaced via SPI bus — depicted in circuit diagrams with pins VCC, GND, MOSI, MISO, SCK, and SS (Slave Select), used to read and write ISO/IEC 14443 Type A contactless smart cards and key fobs at ranges up to 5 cm.
Also known as: RC522 module, MFRC522 module, NFC reader module, 13.56 MHz RFID reader, contactless card reader, SPI RFID module.
What the RFID RC522 Module symbol means
The RFID RC522 Module symbol denotes a PCB module containing NXP's MFRC522 contactless reader IC, an onboard PCB antenna, and supporting circuitry. The module communicates with a host microcontroller over a 4-wire SPI interface (MOSI, MISO, SCK, SS) and requires a 3.3 V supply (VCC, GND), making it directly compatible with 3.3 V microcontrollers and compatible with 5 V systems via level shifting.
In circuit schematics, the module symbol shows the SPI control pins (MOSI, MISO, SCK, SS) and power pins (VCC, GND) without a separate antenna pin — the antenna is integrated on the module PCB. The symbol is used in access control, attendance, and IoT project schematics wherever contactless card identification is required.
How to identify the RFID RC522 Module symbol
The RFID RC522 Module symbol is drawn as a rectangle labelled 'RFID RC522' or 'RFID' with six pins: VCC and GND on one side for power, and MOSI, MISO, SCK, SS on the other (or same) side for the SPI interface. No antenna pin is shown because the antenna is integral to the module PCB. The six-pin SPI configuration distinguishes this module from I2C-interfaced RFID modules (which would show SDA, SCL, VCC, GND).
Function in a circuit
The RFID RC522 module generates a 13.56 MHz carrier field via its PCB antenna, energising passive ISO/IEC 14443 Type A tags (Mifare Classic, Mifare Ultralight, Mifare DESFire) within approximately 5 cm. When a card enters the field, the MFRC522 IC performs card detection, anti-collision arbitration, authentication, and data read/write operations. The host microcontroller sends commands via the SPI interface (SS selects the module, MOSI carries commands, MISO returns responses, SCK synchronises the clock) and receives the card's UID and sector data.
Standards: IEC vs ANSI
| IEC 60617 | ISO/IEC 14443-3 and ISO/IEC 14443-4 define the contactless card protocol and data frame format used by the MFRC522. ISO/IEC 15693 is a related standard for longer-range HF RFID tags. The MFRC522 implements the reader side of ISO/IEC 14443 Type A. |
|---|---|
| ANSI/IEEE 315 | ANSI has no dedicated RFID module schematic symbol; North American circuit diagrams represent it as a labelled rectangular block with SPI pins per IEEE 315 block symbol conventions. |
| Key difference | Both IEC and ANSI schematics use the labelled rectangle block for the RC522 module. No specific glyph difference exists between the two standards for this component. ISO/IEC 14443 is the relevant card interface standard in both regions. |
Terminals / pins
| Pin | Name |
|---|---|
| vcc | VCC |
| gnd | GND |
| mosi | MOSI |
| miso | MISO |
| sck | SCK |
| ss | SS |
Typical values
Operating voltage (VCC): 3.3 V DC (absolute maximum 3.6 V; NOT 5 V tolerant on VCC). SPI clock speed: up to 10 MHz. Operating frequency: 13.56 MHz (ISO/IEC 14443 Type A). Read range: up to ~5 cm (dependent on card/fob quality and antenna). Current consumption: ~13 mA (operating), ~10 µA (soft power-down). Supported card types: Mifare Classic (1K, 4K), Mifare Ultralight, Mifare DESFire. Card UID: 4-byte or 7-byte.
Where the RFID RC522 Module symbol is used
- Access control systems: identifying employees or residents by presenting a Mifare card or key fob to unlock doors or gates
- Student and staff attendance recording systems in schools and offices using card swipe at reader modules
- Maker and IoT projects: Arduino and ESP32-based RFID lock, RFID inventory scanner, or RFID jukebox
- Library book tracking and checkout systems using RFID-tagged books and reader stations
- Payment and loyalty card validation terminals in low-security retail applications
- Asset tracking and laboratory sample management using RFID-labelled containers and automated readers
Example
In an Arduino access control schematic, the RFID RC522 Module symbol's VCC connects to the Arduino 3.3 V pin, GND to Arduino GND, MOSI to Arduino D11, MISO to D12, SCK to D13, and SS to D10; when a Mifare card enters the field, the MFRC522 sends the card UID over SPI and the Arduino firmware compares it against a stored whitelist, then pulses a relay output to unlock the door if the UID matches.
Key facts
- The RFID RC522 Module has six pins: VCC (3.3 V), GND, MOSI, MISO, SCK, and SS — all for the SPI interface and power; the 13.56 MHz antenna is integrated on the module PCB.
- The module operates at 3.3 V only — connecting VCC directly to 5 V will damage the MFRC522 IC; a 3.3 V regulator or level translator is required when using with 5 V systems.
- The MFRC522 implements the ISO/IEC 14443 Type A contactless interface, supporting Mifare Classic (1K, 4K), Mifare Ultralight, and NFC Forum Type 2 tags at 13.56 MHz.
- Card UID (Unique Identifier) is 4 bytes (32-bit) for standard Mifare Classic cards and 7 bytes for newer Mifare DESFire/Ultralight EV1 cards; the UID is read during the anti-collision sequence.
- The SPI interface operates at up to 10 MHz; the MFRC522 also supports I2C and UART interfaces via hardware pin configuration, but RC522 modules are almost universally wired for SPI.
- The MFRC522 supports MIFARE cryptographic authentication (CRYPTO1) for reading/writing password-protected sectors of Mifare Classic cards, but CRYPTO1 has known security vulnerabilities and should not be relied on for high-security applications.
- Read range is approximately 3–5 cm under optimal conditions; it is significantly reduced by nearby metal objects, which shield the electromagnetic field of the 13.56 MHz antenna.
Frequently asked questions
What does the RFID RC522 module symbol represent in a circuit diagram?
The RFID RC522 module symbol represents a 13.56 MHz MFRC522-based RFID reader/writer module that communicates with a microcontroller over SPI. It reads ISO/IEC 14443 Type A contactless cards (Mifare) at up to ~5 cm range and exposes six pins: VCC (3.3 V), GND, MOSI, MISO, SCK, and SS.
What pins does the RFID RC522 module have?
The RFID RC522 module has six pins: VCC (3.3 V power supply), GND (ground), MOSI (SPI Master Out Slave In — data to module), MISO (SPI Master In Slave Out — data from module), SCK (SPI clock), and SS (Slave Select — active LOW chip enable). Some modules also break out IRQ (interrupt) and RST (reset) pins.
Can the RC522 module work with a 5 V Arduino?
The MFRC522 IC requires 3.3 V on VCC — connecting 5 V to VCC will damage it. When using with a 5 V Arduino, connect VCC to the Arduino 3.3 V pin (not 5 V). The SPI data pins (MOSI, SCK, SS) can often accept 5 V logic signals (the MFRC522 is 5 V tolerant on I/O pins in most configurations), but check the specific module's datasheet; some modules include level translators.
What cards does the RFID RC522 module read?
The RFID RC522 module reads ISO/IEC 14443 Type A contactless cards operating at 13.56 MHz, including Mifare Classic (1K and 4K), Mifare Ultralight, Mifare Mini, and some NFC Forum Type 2 tags. It does not read 125 kHz EM4100 cards used in older access control systems, which require a different reader IC.
What is the read range of the RFID RC522 module?
The RFID RC522 module reads standard Mifare cards at up to approximately 3–5 cm (30–50 mm). Range depends on card quality, antenna size, and the absence of nearby metallic objects which attenuate the 13.56 MHz field. Key fobs typically read at slightly shorter range than full credit-card-size cards.
What protocol does the RFID RC522 use?
The RFID RC522 module uses the SPI (Serial Peripheral Interface) protocol to communicate with the host microcontroller at up to 10 MHz clock speed. The MFRC522 IC itself implements ISO/IEC 14443 Type A for wireless card communication. Mifare Classic cards use NXP's CRYPTO1 authentication protocol for sector access control.
What standard defines RFID at 13.56 MHz?
ISO/IEC 14443 defines the contactless smart card interface at 13.56 MHz, covering physical characteristics, RF signal interface, initialisation, anticollision, and transmission protocol. ISO/IEC 14443-3 specifies the Type A initialisation and anti-collision used by Mifare cards. ISO/IEC 15693 covers longer-range HF RFID at 13.56 MHz used in item management applications.
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