# RFID-RC522 ## Description Datasheet-driven MFRC522 RFID reader PCB intended to replicate RC522 module behavior at 13.56 MHz with a 3.3 V nominal supply, 2.5 V to 3.3 V operating range, and RC522-style 8-pin host header compatibility. The MFRC522 datasheet is the authoritative source for pin usage, power rail relationships, oscillator requirements, reset/IRQ handling, and antenna interface topology. AVDD, DVDD, and TVDD must be tied to the same 3.3 V rail; PVDD must be equal to or lower than DVDD; unused MFIN must be tied to SVDD or PVSS; SVDD must be tied to a valid supply if not used independently. The design must use a 27.12 MHz crystal meeting CL 10 pF and ESR <= 100 ohms, local 100 nF decoupling on each MFRC522 supply grouping plus bulk capacitance, and an RF front-end based on the MFRC522 application diagram and reference reader matching/tuning network. PCB priorities are short crystal and RF connections, compact placement of decoupling capacitors at supply pins, solid ground reference, and protected antenna region with minimal digital routing through the RF area. ## Project Details - **Owner:** juyoungoh - **Created:** 3/25/2026 - **Last Updated:** 6/7/2026 - **Visibility:** Public - **Frequency:** 13.56MHz - **System Architecture:** flowchart TD HDR["RC522 style 8 pin header"] --> MFRC["MFRC522 reader IC"] PWR["3.3V supply"] --> MFRC XTAL["27.12MHz crystal"] --> MFRC RFNET["RF matching and filter network"] --> ANT["13.56MHz loop antenna"] MFRC --> RFNET MFRC --> IRQ["IRQ and reset"] - **Operating Voltage:** 2.5V to 3.3V - **Datasheet URL:** https://cdn.flux.ai/project/chat/attachments/MFRC522-276dc3c0-acdf-4441-9ee8-df3d1108a51c.pdf - **Connectivity:** RC522-style 8-pin header compatible with SPI, I2C, and UART pin multiplexing - **Power Requirements:** 3.3V nominal supply for MFRC522; AVDD, DVDD, TVDD equal; PVDD same or lower than DVDD; 13.56MHz operation - **Reference Design URL:** https://cdn.flux.ai/project/chat/attachments/020725103444-9fff7646-c080-4833-b0e3-dea3c9823cef.pdf ## Key Components ### IC1 — [MFRC52202HN1,115](https://www.flux.ai/adrian95/mfrc52202hn1c115~1es.md) - Package: HVQFN-32_L5.0-W5.0-P0.50-TL-EP3.1 - Manufacturer Part Number: MFRC52202HN1,115 - Power Requirements: AVDD=DVDD=TVDD=3.3V nominal; PVDD=SVDD tied to 3.3V in this design; 2.5V to 3.3V operating target - Connectivity: Default boot strap selects SPI mode; RC522 header preserves multiplexed SPI/I2C/UART pin positions - Role: RFID Reader IC - Manufacturer Name: NXP USA Inc. - Role Details: MFRC522-compatible 13.56 MHz RFID front-end with SPI, I2C, and UART host interfaces **Pins:** - AUX1 [pin 19] - AUX2 [pin 20] - AVDD [pin 15] - AVSS [pin 18] - D1/ADR_5 [pin 25] - D2/ADR_4 [pin 26] - D3/ADR_3 [pin 27] - D4/ADR_2 [pin 28] - D5/ADR_1/SCK/DTRQ [pin 29] - D6/ADR_0/MOSI/MX [pin 30] - D7/SCL/MISO/TX [pin 31] - DVDD [pin 3] - DVSS [pin 4] - EA [pin 32] - EP [pin 33] - I2C [pin 1] - IRQ [pin 23] - MFIN [pin 7] - MFOUT [pin 8] - NRSTPD [pin 6] - OSCIN [pin 21] - OSCOUT [pin 22] - PVDD [pin 2] - PVSS [pin 5] - RX [pin 17] - SDA/NSS/RX [pin 24] - SVDD [pin 9] - TVDD [pin 12] - TVSS_1 [pin 10] - TVSS_2 [pin 14] - TX1 [pin 11] - TX2 [pin 13] - VMID [pin 16] ### J1 — [640456-8](https://www.flux.ai/adrian95/640456-8~4qu.md) - Pin 5 Function: MISO/SCL/Tx - Datasheet URL: https://datasheet.datasheetarchive.com/originals/distributors/Datasheets_SAMA/53b6d75d7446c4158b7609f45acef8cd.pdf - Pin 6 Function: MOSI - Connector Rows: 1 - Manufacturer Part Number: 640456-8 - Package: Through Hole 1x8 2.54mm - Manufacturer Name: TE Connectivity - Pin 8 Function: SS/SDA/Rx - Pin 2 Function: RST - Connector Gender: Male - Role: Host Interface Header - Connector Positions: 8 - Pin 3 Function: GND - License: https://creativecommons.org/licenses/by/4.0/ - Pin 1 Function: VCC - Connector Type: Headers and Wire Housings - Connector Pitch: 2.54mm - Pin 7 Function: SCK - Pin 4 Function: IRQ - Part Type: Connector - Role Details: Module-style 8-pin host connector carrying VCC, RST, GND, IRQ, MISO/SCL/Tx, MOSI, SCK, SS/SDA/Rx - Package or Case Code: SHDR8W66P0X254_1X8_2032X572X1024P **Pins:** - 1 [pin 1] - 2 [pin 2] - 3 [pin 3] - 4 [pin 4] - 5 [pin 5] - 6 [pin 6] - 7 [pin 7] - 8 [pin 8] ### X1 — [TXM27.12M0004322DBBDO00T](https://www.flux.ai/lcsc/txm27p12m0004322dbbdo00t~xe6b.md) - Role: Clock - JLCPCB Part Class: Extended Part - Product Info Url: https://lcsc.com/product-detail/Others_Zhejiang-Abel-Elec-SMD-3225-4P-27-12MHZ-10PF-10PPM-40-85_C362365.html - Package: 3225-4 - Role Details: 27.12 MHz reference crystal for MFRC522 OSCIN and OSCOUT - Datasheet URL: https://storage.googleapis.com/graviton-electric-symbols/document_assets/lcsc/1912111437_Yajingxin-TXM27-12M0004322DBBDO00T_C362365.pdf - Part Type: Crystals - Manufacturer Part Number: TXM27.12M0004322DBBDO00T - Package or Case Code: CRYSTAL-SMD_4P-L3.2-W2.5-BL - Manufacturer Name: YJX(雅晶鑫) - LCSC Part Number: C362365 **Pins:** - ~{OE} [pin 1] - GND [pin 2] - GND [pin 4] - OUT [pin 3] *The full schematic, PCB layout, bill of materials, and interactive design are available at [https://www.flux.ai/juyoungoh/rfid-rc522~av](https://www.flux.ai/juyoungoh/rfid-rc522~av).* --- *Generated from [https://www.flux.ai/juyoungoh/rfid-rc522~av](https://www.flux.ai/juyoungoh/rfid-rc522~av)*