Problem with my code or something in IsNewCardPresent()

[dageci]

Step 1: Describe your environment

• OS version: W10 (latest)
• Arduino IDE version: 1.8.19
• MFRC522 Library version: 1.4.10
• Arduino device: ESP32
• MFRC522 device: MINI RFID - RC522

Step 2: Describe the problem

Sometimes it works and sometimes it doesn't pass the testing of PICC_IsNewCardPresent when I restart the power.

I have added the esp32 led on of to see if it pass this if block:

   if ( ! mfrc522.PICC_IsNewCardPresent()) {
      return;
   }
   digitalWrite(LED_BUILTIN, HIGH);
   delay(200);
   digitalWrite(LED_BUILTIN, LOW);

Sometimes, when it works the led blinks, but sometimes when I switch the power off and then back on, it doesn't pass.

When I put the led blinking inside this if block it is blinking:

   if ( ! mfrc522.PICC_IsNewCardPresent()) {
      digitalWrite(LED_BUILTIN, HIGH);
      delay(200);
      digitalWrite(LED_BUILTIN, LOW);
      return;
   }

So I'm not sure if my code is wrong, or is there something else?

Relevant Code:

 #include <SPI.h>
#include <MFRC522.h>
#include "BluetoothSerial.h"

#define SS_PIN 5
#define RST_PIN 22

MFRC522 mfrc522(SS_PIN, RST_PIN);
MFRC522::MIFARE_Key key;

#if !defined(CONFIG_BT_ENABLED) || !defined(CONFIG_BLUEDROID_ENABLED)
#error Bluetooth is not enabled! Please run `make menuconfig` to and enable it
#endif
BluetoothSerial SerialBT;

void setup() {
   Serial.begin(115200); 
   SPI.begin();      // Initiate  SPI bus
   mfrc522.PCD_Init();   // Initiate MFRC522

  for (byte i = 0; i < 6; i++) {
    key.keyByte[i] = 0xFF;  
  }

   SerialBT.begin("RFID Card Reader");

  // initialize digital pin LED_BUILTIN as an output.
  pinMode(LED_BUILTIN, OUTPUT);

}

void loop() {

   if ( ! mfrc522.PICC_IsNewCardPresent()) {
      return;
   }

   //  just to test if it goes here (blink blue led on esp32)
   digitalWrite(LED_BUILTIN, HIGH);
   delay(200);
   digitalWrite(LED_BUILTIN, LOW);

   // Select one of the cards
   if ( ! mfrc522.PICC_ReadCardSerial()) {
      return;
   }

   char str[32] = "";
   array_to_string(mfrc522.uid.uidByte, 4, str); 
   Serial.println(str); 
  SerialBT.print(str);
  SerialBT.println(); 
  delay(1000);  

   mfrc522.PICC_HaltA();

  mfrc522.PCD_StopCrypto1();

}

void array_to_string(byte array[], unsigned int len, char buffer[])
{
   for (unsigned int i = 0; i < len; i++)
   {
      if (i == 0)
        sprintf(buffer, "%02X", array[i]);
      else
        sprintf(&buffer[i*3-1], ":%02X", array[i]);
   }
}

[dageci]

Maybe I have wrongly wired ESP32 & RC522. In another forum I have find out that I can't use all the GPIO's for RS522.

I'm new to this, if you could take a look if this is ok what I have connected. I'm using an ESP32 D1 mini

And my wiring is:

RC522 > ESP32

SDA > I05 SCK > I018 MOSI > I023 MISO > I019 IRQ GND > GND RST > I022 3v3 > 3v3

Is that ok?

[Rotzbua]

You are right. On ESP boards you can not use any pin. There are a few ambiguities and stumbles with the pins.

If the setup works than all good 👍

A recommendable overview is from Andreas Spiess on YT: https://www.youtube.com/watch?v=LY-1DHTxRAk