Hi Crami,

Many thanks for your response. Unfortunately I don't have a drill so I can't enforce I2C mode. I've tried to change the code to use SPI instead. Now I can't get it to write at all and receive the following errors:

#include "MFRC522.h"
#include <M5Stack.h>

// 0x28 is i2c address on SDA. Check your address with i2cscanner if not match.
MFRC522 mfrc522(0x15, 0x02);   // Create MFRC522 instance.

void setup() {
  M5.begin();
  M5.Power.begin();
  M5.Lcd.fillScreen( BLACK );
  M5.Lcd.setCursor(0, 0);
  M5.Lcd.setTextColor(YELLOW);  
  M5.Lcd.setTextSize(2);

  M5.Lcd.fillScreen( BLACK );
  M5.Lcd.setCursor(0, 0);
  M5.Lcd.println("M5StackFire MFRC522");
  Serial.begin(115200);           // Initialize serial communications with the PC
  SPI.begin();                   // Initialize I2C
  
  mfrc522.PCD_Init();             // Init MFRC522
  ShowReaderDetails();            // Show details of PCD - MFRC522 Card Reader details
  Serial.println(F("Scan PICC to see UID, type, and data blocks..."));
  M5.Lcd.println("Scan PICC to see UID, type, and data blocks...");
}

void loop() {
  // Look for new cards, and select one if present
  if ( ! mfrc522.PICC_IsNewCardPresent() || ! mfrc522.PICC_ReadCardSerial() ) {
    delay(50);
    return;
  }
  
  // Now a card is selected. The UID and SAK is in mfrc522.uid.
  
  // Dump UID
  Serial.print(F("Card UID:"));
  M5.Lcd.println(" ");
  for (byte i = 0; i < mfrc522.uid.size; i++) {
    Serial.print(mfrc522.uid.uidByte[i] < 0x10 ? " 0" : " ");
    Serial.print(mfrc522.uid.uidByte[i], HEX);
    M5.Lcd.print(mfrc522.uid.uidByte[i] < 0x10 ? " 0" : " ");
    M5.Lcd.print(mfrc522.uid.uidByte[i], HEX);
  } 
  Serial.println();
  
}

void ShowReaderDetails() {
  // Get the MFRC522 software version
  byte v = mfrc522.PCD_ReadRegister(mfrc522.VersionReg);
  Serial.print(F("MFRC522 Software Version: 0x"));
  Serial.print(v, HEX);
  if (v == 0x91)
    Serial.print(F(" = v1.0"));
  else if (v == 0x92)
    Serial.print(F(" = v2.0"));
  else
    Serial.print(F(" (unknown)"));
  Serial.println("");
  // When 0x00 or 0xFF is returned, communication probably failed
  if ((v == 0x00) || (v == 0xFF)) {
    Serial.println(F("WARNING: Communication failure, is the MFRC522 properly connected?"));
  }
}

Errors:

Arduino: 1.8.12, Board: "M5Stack-Core-ESP32, QIO, 80MHz, Default, 921600, None"

Sketch uses 356605 bytes (27%) of program storage space. Maximum is 1310720 bytes.
Global variables use 17628 bytes (5%) of dynamic memory, leaving 310052 bytes for local variables. Maximum is 327680 bytes.
esptool.py v2.6
Serial port COM3
Connecting....
Chip is ESP32D0WDQ6 (revision 1)
Features: WiFi, BT, Dual Core, 240MHz, VRef calibration in efuse, Coding Scheme None
Uploading stub...
Running stub...
Stub running...
Changing baud rate to 921600
Changed.
Configuring flash size...
Warning: Could not auto-detect Flash size (FlashID=0x0, SizeID=0x0), defaulting to 4MB
Compressed 8192 bytes to 47...

Writing at 0x0000e000... (100 %)
Wrote 8192 bytes (47 compressed) at 0x0000e000 in 0.0 seconds (effective 6553.6 kbit/s)...

A fatal error occurred: Timed out waiting for packet header
A fatal error occurred: Timed out waiting for packet header

Can you spot anything I may be doing wrong?

Hi Crami,

Thanks so much for the reply. I've tried to wire up the unit as you described. Unfortunately I cannot make use of the groove connector because the jumper wire connectors are too large to all fit in the socket and I don't have any other wires.

Instead I've wired:
SDA -> SDA,
SCL -> SCK (Instead of SCL/MISO),
3V3 -> 3.3V and G -> GND.

As for the code, it does #include <wire.h> (seems I cut if off the embed accidentally!)

Unfortunately, still doesn't get past the println below:

I should also mention there is a high pitched buzzing coming from the m5stack?

Here's a the output from the serial plotter too:

Hi all,

I'm trying to run the example RFID M5Stack code on a standalone MFRC522 unit (from eBay) but having quite few issues getting the code to work.

I can download the sample code to the stack and it displays 'M5StackFire MFRC522' on the display but does not read any RFID tags. I first connected the pins:

SDA > SDA
SCK > SCK
MOSI > MO
MISO > MI
GND > G
RST > RST (but on another bus, not sure I can do this)
3.3V > 3V3

The tag was not recognised however. It seems the code never executes past mfrc522.PCD_Init(); (Although I'm really not sure where it gets stuck to be honest)

Using the I2C scanner, a device was registered at address 0x10.

I then realised as the code was using the I2C protocol I only needed to use the lines associated with I2C so wired up the following from the unit to the stack:

SDA, MISO (SCL) , GND, RST and 3.3v

Now the I2C scanner showed no devices attached at all.

Any thoughts on what I may be doing wrong?

Here's a picture of how I've wired it up:

#include "MFRC522_I2C.h"
#include <M5Stack.h>

// 0x28 is i2c address on SDA. Check your address with i2cscanner if not match.
MFRC522 mfrc522(0x10);   // Create MFRC522 instance.

void setup() {
  M5.begin();
  M5.Power.begin();
  M5.Lcd.fillScreen( BLACK );
  M5.Lcd.setCursor(0, 0);
  M5.Lcd.setTextColor(YELLOW);  
  M5.Lcd.setTextSize(2);

  M5.Lcd.fillScreen( BLACK );
  M5.Lcd.setCursor(0, 0);
  M5.Lcd.println("M5StackFire MFRC522");
  Serial.begin(115200);           // Initialize serial communications with the PC
  Wire.begin();                   // Initialize I2C
  
  mfrc522.PCD_Init();             // Init MFRC522
  ShowReaderDetails();            // Show details of PCD - MFRC522 Card Reader details
  Serial.println(F("Scan PICC to see UID, type, and data blocks..."));
  M5.Lcd.println("Scan PICC to see UID, type, and data blocks...");
}

void loop() {
  // Look for new cards, and select one if present
  if ( ! mfrc522.PICC_IsNewCardPresent() || ! mfrc522.PICC_ReadCardSerial() ) {
    delay(50);
    return;
  }
  
  // Now a card is selected. The UID and SAK is in mfrc522.uid.
  
  // Dump UID
  Serial.print(F("Card UID:"));
  M5.Lcd.println(" ");
  for (byte i = 0; i < mfrc522.uid.size; i++) {
    Serial.print(mfrc522.uid.uidByte[i] < 0x10 ? " 0" : " ");
    Serial.print(mfrc522.uid.uidByte[i], HEX);
    M5.Lcd.print(mfrc522.uid.uidByte[i] < 0x10 ? " 0" : " ");
    M5.Lcd.print(mfrc522.uid.uidByte[i], HEX);
  } 
  Serial.println();
  
}

void ShowReaderDetails() {
  // Get the MFRC522 software version
  byte v = mfrc522.PCD_ReadRegister(mfrc522.VersionReg);
  Serial.print(F("MFRC522 Software Version: 0x"));
  Serial.print(v, HEX);
  if (v == 0x91)
    Serial.print(F(" = v1.0"));
  else if (v == 0x92)
    Serial.print(F(" = v2.0"));
  else
    Serial.print(F(" (unknown)"));
  Serial.println("");
  // When 0x00 or 0xFF is returned, communication probably failed
  if ((v == 0x00) || (v == 0xFF)) {
    Serial.println(F("WARNING: Communication failure, is the MFRC522 properly connected?"));
  }
}