Arduino RFID project help

Using Arduino Programming Questions
1

Hello all! Since I discovered the Uno five years ago, I wish I would have years before that. I've built 3 3D printers, a plasma cutter running grbl, Iot wifi controllers, dc servo motor positionners and even a new brain for our dishwasher that's still going strong!

I'm working on a new proof of concept project I could use a hand with. I've been trying code for three days and I'm running into many problems. Basically, I'm looking at a Mifare 1K card system for a transit system with an Uno and a RFID-RC522 card. We have a variable we will call "transfer". Let's say we set a new card, block 4 (completely random) to read 00. Declares "transfer" as 00. What I need, is code to read block 4 on the card. If it's a 00, then it will know it's new and write block 4 to a 01. Declares "transfer" as 01. So next time it reads block 4 and sees a 01, it knows it's used, thus rewriting to a 00, declaring "transfer" to 00, and so on. I hope this is clear as mud.

I don't have any code to post as I've been modding the librairies only to understand. I've been successful at writing the 00 and 01 and reading, just cannot figure out how to make it become a variable I can check. I would appreciate the help. I'm not being lazy, I'm a 49 year old blue collar worker that is just frustrated that he cannot figure this out on his own. If anything becomes of this, I would gladly footnote or pay for the help.

Thanks to all in advance and kudos to all supporters of this forum!

2

Does the Mifare 1K card system not come with any sample code? Maybe we have a look at that.

3

I just purchased a few China cards and key tags to try that use the same protocol. When I use the Dumpinfo in examples library, it recognizes as Mifare 1K.

4

Well, I'm not much good working with nothing. Maybe attach the library(ies) and any user docs?

5

I've been playing with this code, it's as is in librairy.

/**
 * ----------------------------------------------------------------------------
 * This is a MFRC522 library example; see https://github.com/miguelbalboa/rfid
 * for further details and other examples.
 * 
 * NOTE: The library file MFRC522.h has a lot of useful info. Please read it.
 * 
 * Released into the public domain.
 * ----------------------------------------------------------------------------
 * This sample shows how to read and write data blocks on a MIFARE Classic PICC
 * (= card/tag).
 * 
 * BEWARE: Data will be written to the PICC, in sector #1 (blocks #4 to #7).
 * 
 * 
 * Typical pin layout used:
 * -----------------------------------------------------------------------------------------
 *             MFRC522      Arduino       Arduino   Arduino    Arduino          Arduino
 *             Reader/PCD   Uno/101       Mega      Nano v3    Leonardo/Micro   Pro Micro
 * Signal      Pin          Pin           Pin       Pin        Pin              Pin
 * -----------------------------------------------------------------------------------------
 * RST/Reset   RST          9             5         D9         RESET/ICSP-5     RST
 * SPI SS      SDA(SS)      10            53        D10        10               10
 * SPI MOSI    MOSI         11 / ICSP-4   51        D11        ICSP-4           16
 * SPI MISO    MISO         12 / ICSP-1   50        D12        ICSP-1           14
 * SPI SCK     SCK          13 / ICSP-3   52        D13        ICSP-3           15
 * 
 */

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

#define RST_PIN         9           // Configurable, see typical pin layout above
#define SS_PIN          10          // Configurable, see typical pin layout above

MFRC522 mfrc522(SS_PIN, RST_PIN);   // Create MFRC522 instance.

MFRC522::MIFARE_Key key;

/**
 * Initialize.
 */
void setup() {
    Serial.begin(9600); // Initialize serial communications with the PC
    while (!Serial);    // Do nothing if no serial port is opened (added for Arduinos based on ATMEGA32U4)
    SPI.begin();        // Init SPI bus
    mfrc522.PCD_Init(); // Init MFRC522 card

    // Prepare the key (used both as key A and as key B)
    // using FFFFFFFFFFFFh which is the default at chip delivery from the factory
    for (byte i = 0; i < 6; i++) {
        key.keyByte[i] = 0xFF;
    }

    Serial.println(F("Scan a MIFARE Classic PICC to demonstrate read and write."));
    Serial.print(F("Using key (for A and B):"));
    dump_byte_array(key.keyByte, MFRC522::MF_KEY_SIZE);
    Serial.println();
    
    Serial.println(F("BEWARE: Data will be written to the PICC, in sector #1"));
}

/**
 * Main loop.
 */
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(F("Card UID:"));
    dump_byte_array(mfrc522.uid.uidByte, mfrc522.uid.size);
    Serial.println();
    Serial.print(F("PICC type: "));
    MFRC522::PICC_Type piccType = mfrc522.PICC_GetType(mfrc522.uid.sak);
    Serial.println(mfrc522.PICC_GetTypeName(piccType));

    // Check for compatibility
    if (    piccType != MFRC522::PICC_TYPE_MIFARE_MINI
        &&  piccType != MFRC522::PICC_TYPE_MIFARE_1K
        &&  piccType != MFRC522::PICC_TYPE_MIFARE_4K) {
        Serial.println(F("This sample only works with MIFARE Classic cards."));
        return;
    }

    // In this sample we use the second sector,
    // that is: sector #1, covering block #4 up to and including block #7
    byte sector         = 1;
    byte blockAddr      = 4;
    byte dataBlock[]    = {
        0x00, 0x02, 0x03, 0x04, //  1,  2,   3,  4, //////// I'm trying to convert the 00x00 to a variable.
        0x05, 0x06, 0x07, 0x08, //  5,  6,   7,  8,
        0x08, 0x09, 0xff, 0x0b, //  9, 10, 255, 12,
        0x0c, 0x0d, 0x0e, 0x0f  // 13, 14,  15, 16
    };
    byte trailerBlock   = 7;
    MFRC522::StatusCode status;
    byte buffer[18];
    byte size = sizeof(buffer);

    // Authenticate using key A
    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;
    }

    // Show the whole sector as it currently is
    Serial.println(F("Current data in sector:"));
    mfrc522.PICC_DumpMifareClassicSectorToSerial(&(mfrc522.uid), &key, sector);
    Serial.println();

    // Read data from the block
    Serial.print(F("Reading data from block ")); Serial.print(blockAddr);
    Serial.println(F(" ..."));
    status = (MFRC522::StatusCode) mfrc522.MIFARE_Read(blockAddr, buffer, &size);
    if (status != MFRC522::STATUS_OK) {
        Serial.print(F("MIFARE_Read() failed: "));
        Serial.println(mfrc522.GetStatusCodeName(status));
    }
    Serial.print(F("Data in block ")); Serial.print(blockAddr); Serial.println(F(":"));
    dump_byte_array(buffer, 16); Serial.println();
    Serial.println();

    // Authenticate using key B
    Serial.println(F("Authenticating again using key B..."));
    status = (MFRC522::StatusCode) mfrc522.PCD_Authenticate(MFRC522::PICC_CMD_MF_AUTH_KEY_B, trailerBlock, &key, &(mfrc522.uid));
    if (status != MFRC522::STATUS_OK) {
        Serial.print(F("PCD_Authenticate() failed: "));
        Serial.println(mfrc522.GetStatusCodeName(status));
        return;
    }

    // Write data to the block
    Serial.print(F("Writing data into block ")); Serial.print(blockAddr);
    Serial.println(F(" ..."));
    dump_byte_array(dataBlock, 16); Serial.println();
    status = (MFRC522::StatusCode) mfrc522.MIFARE_Write(blockAddr, dataBlock, 16);
    if (status != MFRC522::STATUS_OK) {
        Serial.print(F("MIFARE_Write() failed: "));
        Serial.println(mfrc522.GetStatusCodeName(status));
    }
    Serial.println();

    // Read data from the block (again, should now be what we have written)
    Serial.print(F("Reading data from block ")); Serial.print(blockAddr);
    Serial.println(F(" ..."));
    status = (MFRC522::StatusCode) mfrc522.MIFARE_Read(blockAddr, buffer, &size);
    if (status != MFRC522::STATUS_OK) {
        Serial.print(F("MIFARE_Read() failed: "));
        Serial.println(mfrc522.GetStatusCodeName(status));
    }
    Serial.print(F("Data in block ")); Serial.print(blockAddr); Serial.println(F(":"));
    dump_byte_array(buffer, 16); Serial.println();
        
    // Check that data in block is what we have written
    // by counting the number of bytes that are equal
    Serial.println(F("Checking result..."));
    byte count = 0;
    for (byte i = 0; i < 16; i++) {
        // Compare buffer (= what we've read) with dataBlock (= what we've written)
        if (buffer[i] == dataBlock[i])
            count++;
    }
    Serial.print(F("Number of bytes that match = ")); Serial.println(count);
    if (count == 16) {
        Serial.println(F("Success :-)"));
    } else {
        Serial.println(F("Failure, no match :-("));
        Serial.println(F("  perhaps the write didn't work properly..."));
    }
    Serial.println();
        
    // Dump the sector data
    Serial.println(F("Current data in sector:"));
    mfrc522.PICC_DumpMifareClassicSectorToSerial(&(mfrc522.uid), &key, sector);
    Serial.println();

    // Halt PICC
    mfrc522.PICC_HaltA();
    // Stop encryption on PCD
    mfrc522.PCD_StopCrypto1();
}

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

Down about halfway 0x00 is the first thing it writes to datablock4. I need to know how to turn this into a variable i can check with if_else.

First time posting code, hope this works.

6

So if you scroll down to read data, I have modded here in comments, I get it to read the first bit of block 4. I need to convert this to a variable for my if_else statement.

Thanks again Watson

 /**
 * ----------------------------------------------------------------------------
 * This is a MFRC522 library example; see https://github.com/miguelbalboa/rfid
 * for further details and other examples.
 * 
 * NOTE: The library file MFRC522.h has a lot of useful info. Please read it.
 * 
 * Released into the public domain.
 * ----------------------------------------------------------------------------
 * This sample shows how to read and write data blocks on a MIFARE Classic PICC
 * (= card/tag).
 * 
 * BEWARE: Data will be written to the PICC, in sector #1 (blocks #4 to #7).
 * 
 * 
 * Typical pin layout used:
 * -----------------------------------------------------------------------------------------
 *             MFRC522      Arduino       Arduino   Arduino    Arduino          Arduino
 *             Reader/PCD   Uno/101       Mega      Nano v3    Leonardo/Micro   Pro Micro
 * Signal      Pin          Pin           Pin       Pin        Pin              Pin
 * -----------------------------------------------------------------------------------------
 * RST/Reset   RST          9             5         D9         RESET/ICSP-5     RST
 * SPI SS      SDA(SS)      10            53        D10        10               10
 * SPI MOSI    MOSI         11 / ICSP-4   51        D11        ICSP-4           16
 * SPI MISO    MISO         12 / ICSP-1   50        D12        ICSP-1           14
 * SPI SCK     SCK          13 / ICSP-3   52        D13        ICSP-3           15
 * 
 */

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

#define RST_PIN         9           // Configurable, see typical pin layout above
#define SS_PIN          10          // Configurable, see typical pin layout above

MFRC522 mfrc522(SS_PIN, RST_PIN);   // Create MFRC522 instance.

MFRC522::MIFARE_Key key;

/**
 * Initialize.
 */
void setup() {
    Serial.begin(9600); // Initialize serial communications with the PC
    while (!Serial);    // Do nothing if no serial port is opened (added for Arduinos based on ATMEGA32U4)
    SPI.begin();        // Init SPI bus
    mfrc522.PCD_Init(); // Init MFRC522 card

    // Prepare the key (used both as key A and as key B)
    // using FFFFFFFFFFFFh which is the default at chip delivery from the factory
    for (byte i = 0; i < 6; i++) {
        key.keyByte[i] = 0xFF;
    }

    Serial.println(F("Scan a MIFARE Classic PICC to demonstrate read and write."));
    Serial.print(F("Using key (for A and B):"));
    dump_byte_array(key.keyByte, MFRC522::MF_KEY_SIZE);
    Serial.println();
    
    Serial.println(F("BEWARE: Data will be written to the PICC, in sector #1"));
}

/**
 * Main loop.
 */
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(F("Card UID:"));
    dump_byte_array(mfrc522.uid.uidByte, mfrc522.uid.size);
    Serial.println();
    Serial.print(F("PICC type: "));
    MFRC522::PICC_Type piccType = mfrc522.PICC_GetType(mfrc522.uid.sak);
    Serial.println(mfrc522.PICC_GetTypeName(piccType));

    // Check for compatibility
    if (    piccType != MFRC522::PICC_TYPE_MIFARE_MINI
        &&  piccType != MFRC522::PICC_TYPE_MIFARE_1K
        &&  piccType != MFRC522::PICC_TYPE_MIFARE_4K) {
        Serial.println(F("This sample only works with MIFARE Classic cards."));
        return;
    }

    // In this sample we use the second sector,
    // that is: sector #1, covering block #4 up to and including block #7
    byte sector         = 1;
    byte blockAddr      = 4;
    byte dataBlock[]    = {
        0x01, 0x01, 0x01, 0x01, //  1,  2,   3,  4,
        0x05, 0x06, 0x07, 0x08, //  5,  6,   7,  8,
        0x08, 0x09, 0xff, 0x0b, //  9, 10, 255, 12,
        0x0c, 0x0d, 0x0e, 0x0f  // 13, 14,  15, 16
    };
    byte trailerBlock   = 7;
    MFRC522::StatusCode status;
    byte buffer[18];
    byte size = sizeof(buffer);

    // Authenticate using key A
    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;
    }

    // Show the whole sector as it currently is
    Serial.println(F("Current data in sector:"));
    mfrc522.PICC_DumpMifareClassicSectorToSerial(&(mfrc522.uid), &key, sector);
    Serial.println();

    // Read data from the block
    Serial.print(F("Reading data from block ")); Serial.print(blockAddr);
    Serial.println(F(" ..."));
    status = (MFRC522::StatusCode) mfrc522.MIFARE_Read(blockAddr, buffer, &size);
    if (status != MFRC522::STATUS_OK) {
        Serial.print(F("MIFARE_Read() failed: "));
        Serial.println(mfrc522.GetStatusCodeName(status));
    }
    Serial.print(F("Data in block ")); Serial.print(blockAddr); Serial.println(F(":")); /// modded here
    dump_byte_array(buffer, 1); Serial.println(); /// modded here 1 was 16
    Serial.println(); /// modded here

    // Authenticate using key B
    Serial.println(F("Authenticating again using key B..."));
    status = (MFRC522::StatusCode) mfrc522.PCD_Authenticate(MFRC522::PICC_CMD_MF_AUTH_KEY_B, trailerBlock, &key, &(mfrc522.uid));
    if (status != MFRC522::STATUS_OK) {
        Serial.print(F("PCD_Authenticate() failed: "));
        Serial.println(mfrc522.GetStatusCodeName(status));
        return;
    }

    // Write data to the block
    Serial.print(F("Writing data into block ")); Serial.print(blockAddr);
    Serial.println(F(" ..."));
    dump_byte_array(dataBlock, 16); Serial.println();
    status = (MFRC522::StatusCode) mfrc522.MIFARE_Write(blockAddr, dataBlock, 16);
    if (status != MFRC522::STATUS_OK) {
        Serial.print(F("MIFARE_Write() failed: "));
        Serial.println(mfrc522.GetStatusCodeName(status));
    }
    Serial.println();

    // Read data from the block (again, should now be what we have written)
    Serial.print(F("Reading data from block ")); Serial.print(blockAddr);
    Serial.println(F(" ..."));
    status = (MFRC522::StatusCode) mfrc522.MIFARE_Read(blockAddr, buffer, &size);
    if (status != MFRC522::STATUS_OK) {
        Serial.print(F("MIFARE_Read() failed: "));
        Serial.println(mfrc522.GetStatusCodeName(status));
    }
    Serial.print(F("Data in block ")); Serial.print(blockAddr); Serial.println(F(":"));
    dump_byte_array(buffer, 16); Serial.println();
        
    // Check that data in block is what we have written
    // by counting the number of bytes that are equal
    Serial.println(F("Checking result..."));
    byte count = 0;
    for (byte i = 0; i < 16; i++) {
        // Compare buffer (= what we've read) with dataBlock (= what we've written)
        if (buffer[i] == dataBlock[i])
            count++;
    }
    Serial.print(F("Number of bytes that match = ")); Serial.println(count);
    if (count == 16) {
        Serial.println(F("Success :-)"));
    } else {
        Serial.println(F("Failure, no match :-("));
        Serial.println(F("  perhaps the write didn't work properly..."));
    }
    Serial.println();
        
    // Dump the sector data
    Serial.println(F("Current data in sector:"));
    mfrc522.PICC_DumpMifareClassicSectorToSerial(&(mfrc522.uid), &key, sector);
    Serial.println();

    // Halt PICC
    mfrc522.PICC_HaltA();
    // Stop encryption on PCD
    mfrc522.PCD_StopCrypto1();
}

/**
 * Helper routine to dump a byte array as hex values to Serial.
 */
void dump_byte_array(byte *buffer, byte bufferSize) {
    for (byte i = 0; i < bufferSize; i++) {
        Serial.print(buffer[i] < 0x10 ? " 0" : " ");
        Serial.print(buffer[i], HEX);
    }
}
7

A little more reading, I think I have to convert the byte array to an int or string before proceeding.

8

Learned a lot of little things today that will help me down the road, but yet to figure my problem out, any help appreciated.

9

Could it be as simple as this ?

void loop() {
	
	byte the_variable_I_want;
	
	// skip down to the section you commented
	
	....
	
	Serial.print(F("Data in block ")); Serial.print(blockAddr); Serial.println(F(":")); /// modded here
	dump_byte_array(buffer, 1); Serial.println(); /// modded here 1 was 16
	
	the_variable_I_want = buffer[0];
	
	Serial.println(); /// modded here
	
	.....
	
	DoStuffWith(the_variable_I_want);
	buffer[0] = the_variable_I_want;
	
	.....
	// Authenticate using key B
	.......
	// Write data to the block
	.......
}
10 
Simple as that?

Yes, sort of. It reads the byte from 0-9 without any issues.  Thanks. Again, I'm new here so no yelling please. In my code, I declare a datablock of bytes to start. First one i set to 0x09 for testing. I scan the tag, it reads the correct byte with the buffer[0] inserted. I have an if_elseif_else to see if byte is 0 1 or 9 (default). It reads as 9 first time. It is then when it redeclares the value of the datablock to rewrite with new but doesn't. Am I allowed to do this or is there another way? Sorry if the code is a little messy. I only posted the part of the code thats not working correctly.



    byte sector         = 1;
    byte blockAddr      = 4;
    byte dataBlock[]    = {
        0x09, 0x02, 0x03, 0x04, //  1,  2,   3,  4,
        0x05, 0x06, 0x07, 0x08, //  5,  6,   7,  8,
        0x08, 0x09, 0xff, 0x0b, //  9, 10, 255, 12,
        0x0c, 0x0d, 0x0e, 0x0f  // 13, 14,  15, 16
    };

/**
 * Main loop.

    // Read data from the block

     transfer = buffer[0];

     Serial.println(transfer);
     Serial.println('\n');

     if (transfer ==0) {
      Serial.println("transfer written");
      //
      byte sector         = 1;
      byte blockAddr      = 4;
      byte dataBlock[]    = {
        0x01, 0x02, 0x03, 0x04, //  1,  2,   3,  4,
        0x05, 0x06, 0x07, 0x08, //  5,  6,   7,  8,
        0x08, 0x09, 0xff, 0x0b, //  9, 10, 255, 12,
        0x0c, 0x0d, 0x0e, 0x0f  // 13, 14,  15, 16
    };
     byte trailerBlock   = 7;
    MFRC522::StatusCode status;
    byte buffer[18];
    byte size = sizeof(buffer);
      //
      
     }
     //
else if (transfer ==1) {
      Serial.println("transfer accepted");
      //
      byte sector         = 1;
      byte blockAddr      = 4;
      byte dataBlock[]    = {
        0x00, 0x02, 0x03, 0x04, //  1,  2,   3,  4,
        0x05, 0x06, 0x07, 0x08, //  5,  6,   7,  8,
        0x08, 0x09, 0xff, 0x0b, //  9, 10, 255, 12,
        0x0c, 0x0d, 0x0e, 0x0f  // 13, 14,  15, 16
    };
    
    byte trailerBlock   = 7;
    MFRC522::StatusCode status;
    byte buffer[18];
    byte size = sizeof(buffer);
      //
      
     }
else {
Serial.println("invalid card");
    byte sector         = 1;
    byte blockAddr      = 4;
    byte dataBlock[]    = {
        0x00, 0x02, 0x03, 0x04, //  1,  2,   3,  4,
        0x05, 0x06, 0x07, 0x08, //  5,  6,   7,  8,
        0x08, 0x09, 0xff, 0x0b, //  9, 10, 255, 12,
        0x0c, 0x0d, 0x0e, 0x0f  // 13, 14,  15, 16
    };
     }
     //
11

I take it that the code does not compile?

There are a couple of issues.

The first portion of you code is okay

    byte sector         = 1;
    byte blockAddr      = 4;
    byte dataBlock[]    = {
        0x09, 0x02, 0x03, 0x04, //  1,  2,   3,  4,
        0x05, 0x06, 0x07, 0x08, //  5,  6,   7,  8,
        0x08, 0x09, 0xff, 0x0b, //  9, 10, 255, 12,
        0x0c, 0x0d, 0x0e, 0x0f  // 13, 14,  15, 16
    };

The portion underneath is not.

     if (transfer ==0) {
      Serial.println("transfer written");
      //

      byte sector         = 1;
      byte blockAddr      = 4;
      byte dataBlock[]    = {
        0x01, 0x02, 0x03, 0x04, //  1,  2,   3,  4,
        0x05, 0x06, 0x07, 0x08, //  5,  6,   7,  8,
        0x08, 0x09, 0xff, 0x0b, //  9, 10, 255, 12,
        0x0c, 0x0d, 0x0e, 0x0f  // 13, 14,  15, 16
    };
    byte trailerBlock   = 7;
    MFRC522::StatusCode status;
    byte buffer[18];
    byte size = sizeof(buffer);

There are a couple of issues here.

  • You are declaring (essentialy trying to create) variables again. You can only declare something once. If what you're trying to do is to assign values, then you need to remove the type specifiers frin non-array type variables (sector and blockAddr) for the array you also need to remove the type specifier and assign each element of the array individually (eg dataBlock[n] = somevalue)
  • The declerations that have no value assignments (eg MFRC522::StatusCode status;) can simply be removed. They should have been declared already, when you read the data from the card

The same two points I made above go for the if (transfer == 1) and else { } blocks in your code as well.

12

Got ya, like so? On my iPad so no coding tags sry.

If (transfer ==0)
{

dataBlock[] = {
0x09, 0x02, 0x03, 0x04, // 1, 2, 3, 4,
0x05, 0x06, 0x07, 0x08, // 5, 6, 7, 8,
0x08, 0x09, 0xff, 0x0b, // 9, 10, 255, 12,
0x0c, 0x0d, 0x0e, 0x0f // 13, 14, 15, 16
};

}

13

try

if (transfer == 0)
  datablock[0] = 0x09;

Unless the other values have changed in the interim, in which case you will have to assign them each individually in a manner similar to the above.

14

Will try tonight, was thinking along those lines. I just need one variable at moment, so it should work fine.

15

Thank you gentlemen. Didn't want to put whole code up, some housekeeping to do first, but buffer and my syntax corrections work perfectly. I will need to write and read more variables somewhere down the line.

/////
//check card loop
/////

transfer = buffer[0];

if (transfer ==0)  {

   Serial.println("Transfer written");
   dataBlock[0]={1};
   
}


Code is basically checking if the card was unused  and converted to a transfer or used already and the transfer cancelled just to be able to track riders on a city bus. Thanks again peeps.

else if (transfer ==1)  {
   Serial.println("Transfer accepted");
   dataBlock[0]={0};
}
else  {
  Serial.println("Transfer denied");
  dataBlock[0]={3};
}

/////
/////
16

Little more toying around and am able to write the route number to another byte, and hour,mins,secs to three other bytes. Getting ahead of myself but it had to be done at one point or another!!

17 
   dataBlock[0]={0};

{What} {is} {the} {point} {of} {wrapping} {the} {value} {in} {useless} {curly} {braces} {?}

18

I assumed they were needed because they were in original code.

Will try to omit {them} for {You}!

19

Well gents, all rolling along. Removed all uneccessary squiggly brackets and it still work! Been looking for something specific in arduino or timlib, I want to make my pass valid for 30 days and then expire? Same as transfer valid for an hour then nothing and charges you fare. Anyone come across a function like this? No code to speak of, I'm just in planning stage (and still at work),lol.

20

I've decided to use UID authentication for my project. Basically scan, check to a database of cards, if true then continue. Is there an easy way to read from a database in the following code for the UIDs? I'm sure I can add them in an if..else manually, but if I have 100 cards? Either a database in code, or eeprom, or SD card? Whichever one would be better for me, I'm not sure. Opinions?

{

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

// Select one of the cards
if ( ! mfrc522.PICC_ReadCardSerial())
{
return;
}
//Show UID
Serial.print("UID :");
String content= "";
byte letter;

for (byte i = 0; i < mfrc522.uid.size; i++)
{
Serial.print(mfrc522.uid.uidByte < 0x10 ? " 0" : " ");
Serial.print(mfrc522.uid.uidByte*, HEX);*
content.concat(String(mfrc522.uid.uidByte < 0x10 ? " 0" : " "));
content.concat(String(mfrc522.uid.uidByte*, HEX));*
}

Serial.println();
Serial.print("Message : ");
content.toUpperCase();

if (content.substring(1) == "A5 7D 2A FF") //access UIDs – this is where I need the database
{
Serial.println("Acess Authorized");
Serial.println();
delay(1000);
}
else
{
Serial.println("Access denied");
delay(1000);
}
}