RC522 RFID with ESP32-C3-DevKitM-1

Wiring for the RC522 RFID reader (13.56 MHz) on the ESP32-C3-DevKitM-1 (ESP32-C3, 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	ESP32-C3-DevKitM-1 pin	Notes
SDA	SPI chip select	7	This is the SPI chip select (CS), despite the SDA label
SCK	SPI clock	4
MOSI	SPI MOSI	6
MISO	SPI MISO	5
IRQ	Interrupt	10	Interrupt, optional. Leave unconnected
GND	Ground	GND
RST	Input to the part	3	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(7, 3);  // 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: esp32:esp32:esp32c3. If uploading does not start, hold BOOT, press and release RST, then release BOOT.

Questions

Which ESP32-C3-DevKitM-1 pins do I use for the RC522 RFID?

SDA → 7, SCK → 4, MOSI → 6, MISO → 5, IRQ → 10, GND → GND, RST → 3, 3.3V → 3V3.

Does the RC522 RFID work with the ESP32-C3-DevKitM-1 at 3.3 V?

Yes: the RC522 RFID runs at 3.3 V and the ESP32-C3-DevKitM-1 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 ESP32-C3-DevKitM-1 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-S3-DevKitC-1 Nordic nRF52840 DK NUCLEO-F401RE Raspberry Pi Pico 2 Raspberry Pi Pico W Raspberry Pi Pico Teensy 4.1

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