RC522 RFID with NUCLEO-F401RE

Wiring for the RC522 RFID reader (13.56 MHz) on the NUCLEO-F401RE (STM32F401RE, 3.3 V logic), chosen with the same pin rules BoardPilot uses: default buses first, and no pins that are used for flash, USB, the debugger or booting.

Wiring

RC522 RFID pin	Role	NUCLEO-F401RE pin	Notes
SDA	SPI chip select	PWM/CS/D10 (PB6)	This is the SPI chip select (CS), despite the SDA label
SCK	SPI clock	SCK/D13 (PA5)
MOSI	SPI MOSI	PWM/MOSI/D11 (PA7)
MISO	SPI MISO	MISO/D12 (PA6)
IRQ	Interrupt	D2 (PA10)	Interrupt, optional. Leave unconnected
GND	Ground	GND
RST	Input to the part	D4 (PB5)	Reset, active LOW
3.3V	Power	3V3	3.3 V only. Never 5 V

Check before you power it on

Supply: 3.3 V from the 3V3 pin.

Test code (Arduino)

// Library: MFRC522 (miguelbalboa)
#include <SPI.h>
#include <MFRC522.h>

MFRC522 rfid(PB6, PB5);  // SDA is the SPI chip select

void setup() {
  Serial.begin(115200);
  SPI.begin();
  rfid.PCD_Init();
  rfid.PCD_DumpVersionToSerial();  // 0x91 or 0x92 means the reader answers
}

void loop() {
  if (!rfid.PICC_IsNewCardPresent() || !rfid.PICC_ReadCardSerial()) return;
  for (byte i = 0; i < rfid.uid.size; i++) Serial.print(rfid.uid.uidByte[i], HEX);
  Serial.println();
  rfid.PICC_HaltA();
}

Arduino board: STMicroelectronics:stm32:Nucleo_64:pnum=NUCLEO_F401RE. Plug the USB cable into the mini-USB port on the ST-LINK end. No button press is needed.

Questions

Which NUCLEO-F401RE pins do I use for the RC522 RFID?

SDA → PWM/CS/D10 (PB6), SCK → SCK/D13 (PA5), MOSI → PWM/MOSI/D11 (PA7), MISO → MISO/D12 (PA6), IRQ → D2 (PA10), GND → GND, RST → D4 (PB5), 3.3V → 3V3.

Does the RC522 RFID work with the NUCLEO-F401RE at 3.3 V?

Yes: the RC522 RFID runs at 3.3 V and the NUCLEO-F401RE uses 3.3 V signals, so no level shifting is needed.

BoardPilot checks this wiring in 3D as you build it, and finds crossed or missing wires on the real board.

Download BoardPilot

Full NUCLEO-F401RE pinout · RC522 RFID reader (13.56 MHz): all pins and data

The RC522 RFID on other boards

ESP32 DevKit Arduino Mega 2560 R3 Arduino Nano Arduino Uno R3 WeAct Black Pill STM32F411CE ESP32-C3-DevKitM-1 ESP32-S3-DevKitC-1 Nordic nRF52840 DK Raspberry Pi Pico 2 Raspberry Pi Pico W Raspberry Pi Pico Teensy 4.1

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