rc522 不移卡多次读写

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

#define SS_PIN 10
#define RST_PIN 9
MFRC522 mfrc522(SS_PIN, RST_PIN);  // Create MFRC522 instance

void setup() {
  Serial.begin(9600);  // Initialize serial communications with the PC
  SPI.begin();         // Init SPI bus
  mfrc522.PCD_Init();  // Init MFRC522 card
  Serial.println("Place your card on the reader and open the Serial Monitor.");
}

void loop() {
  // Look for new cards
  if (!mfrc522.PICC_IsNewCardPresent()) {
    return;
  }

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

  // Show some details of the PICC (that is: the tag/card)
  Serial.print("Card UID: ");
  for (byte i = 0; i < mfrc522.uid.size; i++) {
    Serial.print(mfrc522.uid.uidByte[i] < 0x10 ? " 0" : " ");
    Serial.print(mfrc522.uid.uidByte[i], HEX);
  }
  Serial.println();
  Serial.println("Enter data to write (16 characters max) and press Enter:");

  while (true) {
    Serial.println("等待输入");

    // Allow user to type 'exit' to stop writing
    if (Serial.available()) {
      char cmd = char(Serial.read());
      if (cmd == 'w') {
        writeblack();
      } else {
        reblack();
      }
    }


    // Allow user to type 'exit' to stop writing
    if (Serial.available()) {
      String command = Serial.readString();
      command.trim();
      if (command.equals("exit")) {
        Serial.println("Remove the card.");
        while (mfrc522.PICC_IsNewCardPresent() || mfrc522.PICC_ReadCardSerial()) {
          delay(500);  // Wait until the card is removed
        }
        Serial.println("Place a new card on the reader.");
        break;
      } else if (command.equals("red")) {
        //读取模块
      }
    }

    delay(1000);
  }
}

void writeblack() {

  if (Serial.available()) {
    String inputData = Serial.readString();

    // Ensure the input data is not longer than 16 characters
    if (inputData.length() > 16) {
      inputData = inputData.substring(0, 16);
    }

    byte dataBlock[16];
    inputData.getBytes(dataBlock, 17);  // 16 chars + null terminator

    byte sector = 1;     // Sector to write to
    byte blockAddr = 4;  // Block address within sector
    byte trailerBlock = sector * 4 + 3;

    MFRC522::StatusCode status;
    Serial.print(F("Authenticating using key A..."));
    MFRC522::MIFARE_Key key;
    for (byte i = 0; i < 6; i++) key.keyByte[i] = 0xFF;

    status = mfrc522.PCD_Authenticate(MFRC522::PICC_CMD_MF_AUTH_KEY_A, trailerBlock, &key, &(mfrc522.uid));
    if (status != MFRC522::STATUS_OK) {
      Serial.print(F("PCD_Authenticate() failed: "));
      Serial.println(mfrc522.GetStatusCodeName(status));
      return;
    }

    Serial.println(F("Writing data to block 4..."));
    status = mfrc522.MIFARE_Write(blockAddr, dataBlock, 16);
    if (status != MFRC522::STATUS_OK) {
      Serial.print(F("MIFARE_Write() failed: "));
      Serial.println(mfrc522.GetStatusCodeName(status));
      return;
    }

    Serial.println(F("Data was written successfully. Enter another data or type 'exit' to finish:"));
  }
}

void reblack() {
  MFRC522::StatusCode status;
  byte buffer[18];
  byte size = sizeof(buffer);

  byte sector = 1;     // Sector to write to
  byte blockAddr = 4;  // Block address within sector
  byte trailerBlock = sector * 4 + 3;

  MFRC522::MIFARE_Key key;
  for (byte i = 0; i < 6; i++) key.keyByte[i] = 0xFF;

  // Authenticate using key A  使用密钥A进行授权
  Serial.println(F("Authenticating using key A..."));
  status = (MFRC522::StatusCode)mfrc522.PCD_Authenticate(MFRC522::PICC_CMD_MF_AUTH_KEY_A, trailerBlock, &key, &(mfrc522.uid));
  if (status != MFRC522::STATUS_OK) {
    Serial.print(F("PCD_Authenticate() failed: "));
    Serial.println(mfrc522.GetStatusCodeName(status));
    return;
  }

  status = (MFRC522::StatusCode)mfrc522.MIFARE_Read(blockAddr, buffer, &size);
  if (status != MFRC522::STATUS_OK) {
    Serial.print(F("读取数据块失败: "));
    Serial.println(mfrc522.GetStatusCodeName(status));
    return;  //读取卡片失败，退出
  }
  Serial.print(F("Data in block "));
  Serial.print(blockAddr);
  Serial.print(F(":"));
  printHex(buffer, 16);
}


/**
* Helper routine to dump a byte array as hex values to Serial. 
*/
void printHex(byte* buffer, byte bufferSize) {
  for (byte i = 0; i < bufferSize; i++) {
    Serial.print(buffer[i] < 0x10 ? "0" : "");
    Serial.print(buffer[i], HEX);
    Serial.print(" ");
  }
}