README.md

RFID shared elements

Common elements of all RFID and NFC readers like the type of cards 14443 Type A, Type B, Innovision Jewel.

This contains as well an abstract class that has to be implemented by readers to have a transparent way of managing Mifare, Ultralight cards and other high level cards.

namespace Iot.Device.Card
{
    /// <summary>
    /// Abstract class implementing a specific Write and Read function
    /// This class allow to transceive information with the card
    /// This class has to be implemented in all RFID/NFC/Card readers
    /// So Mifare cards can be used the same way independent of any reader
    /// </summary>
    public abstract class CardTransceiver
    {
        /// <summary>
        /// This function has to be implemented by all NFC/RFID/Card readers. This function is used in exchange of data with
        /// the reader and the cards.
        /// </summary>
        /// <param name="targetNumber">Some readers have a notion of target number for the cards as they can read multiple ones</param>
        /// <param name="dataToSend">A standardized raw buffer with the command at the position 0 in the array</param>
        /// <param name="dataFromCard">If any data are read from the card, they will be put into this array</param>
        /// <returns>-1 in case of error, otherwise the number of bytes read and copied into the <paramref name="dataFromCard"/> array</returns>
        public abstract int Transceive(byte targetNumber, SpanByte dataToSend, SpanByte dataFromCard);

        /// <summary>
        /// Once you have an authentication operation failing with Mifare cards or a read/write, the card stop.
        /// TYhe only way to have it back is to send the unselect and anti collision.
        /// This function provides this feature
        /// </summary>
        /// <param name="targetNumber">The target number to reselect</param>
        /// <returns>True if success</returns>
        public abstract bool ReselectTarget(byte targetNumber);
    }
}