rfid125kHz.cpp

/*
RFID reader.
Based on the "RFID_Readerer" library (https://github.com/travisfarmer) from Travis Farmer.

==================================================================
Copyright (c) 2018 Lubos Ruckl

Permission is hereby granted, free of charge, to any person
obtaining a copy of this software and associated documentation
files (the "Software"), to deal in the Software without
restriction, including without limitation the rights to use,
copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following
conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.
==================================================================

Hardware: RDM6300 or RF125-PS or Gwiot 7941E
Uses 125KHz RFID tags.
*/

#include "Arduino.h"
#include "rfid125kHz.h"

char *RFID_Reader::ulltostr(unsigned long long value, char *ptr, int base)
{
  unsigned long long t = 0, res = 0;
  unsigned long long tmp = value;
  int count = 0;
  if (NULL == ptr)
  {
    return NULL;
  }
  if (tmp == 0)
  {
    count++;
  }
  while (tmp > 0)
  {
    tmp = tmp / base;
    count++;
  }
  ptr += count;
  *ptr = '\0';
  do
  {
    res = value - base * (t = value / base);
    if (res < 10)
    {
      * -- ptr = '0' + res;
    }
    else if ((res >= 10) && (res < 16))
    {
      * --ptr = 'A' - 10 + res;
    }
  } while ((value = t) != 0);
  return (ptr);
}

/*
this is to simply return true when there is RFID data available.
it is a function to prevent external manipulation of the boolean variable.
*/
bool RFID_Reader::Available()
{
    return (data_available);
}

/*
Returns the ID hexadecimal representation, and resets the Available flag.
*/
String RFID_Reader::GetHexID()
{
    if (data_available)
    {
        uint8_t b[5];
        memcpy(b, &new_ID, 5);
        char buf[11];
        sprintf(buf,"%02x%02x%02x%02x%02x",b[4],b[3],b[2],b[1],b[0]);
        lasttagtype = tagtype;
        data_available = false;
        return String(buf);
    }
    return "None";
}

/*
Returns Tag type.
*/
String RFID_Reader::GetTagType()
{
    for (uint8_t x = 0; x < 12; x++) {
        if (typeDict[x].itype == lasttagtype) return String(typeDict[x].stype);
    } 
    return "Unknown";
}



/*
Returns the ID decimal representation, and resets the Available flag.
*/
String RFID_Reader::GetDecID()
{
    if (data_available)
    {
        char ptr[128];
        ulltostr(new_ID, ptr, 10);
        lasttagtype = tagtype;
        data_available = false;
        return String(ptr);
    }
    return "None";
}


void RFID_Reader::rfidSerial(char x)
{
    //if (x == StartByte && (ix==0 || ix > 1))
    if (x == StartByte && ix != 1)
    {
        ix = 0;
    } else if (x == EndByte)
    {
        msg[ix] = '\0';
        msgLen = ix;
        parse();
        ix = 0;
    } else
    {
        msg[ix] = x;
        ix++;
    }
}


uint8_t RFID_Reader::get_checksum(unsigned long long data)
  {
    uint8_t b[5];
    memcpy(b, &data, 5);
    return b[0] ^ b[1] ^ b[2] ^ b[3] ^ b[4];
  }


uint8_t RFID_Reader::char2int(char c)
  {
    c -= asciiNum_diff;
    if(c > 9) c -= asciiUpp_diff;
    return c;
  }


/*
the module spits out HEX values, we need to convert them to an unsigned long.
*/
void RFID_Reader::parse()
{
    uint8_t lshift = 40;
    unsigned long long val = 0;
    unsigned long long tagIdValue = 0;
    uint8_t i;
    uint8_t checksum = 0; 
    uint8_t recChecksum = 0;
    if ((msgLen + 2) == msg[0])//Gwiot 7941E
    {
        for (i = 0; i < msgLen - 1; i++)
        {
        val = msg[i];
        checksum = checksum ^ val;
        if (i > 1)
            {
            //lshift = 8 * (msgLen - 2 - i);
            lshift = (msgLen - 2 - i) << 3;
            tagIdValue |= val << lshift;
            }
        }
        recChecksum = (uint8_t)msg[i];
        tagtype = (uint8_t)msg[1];
        }    
    else
    {
        for (i = 0; i < 10; i++) {
            val = char2int(msg[i]);
            //lshift = 4 * (9 - i);
            lshift -= 4;
            tagIdValue |= val << lshift;
        }
        checksum = get_checksum(tagIdValue); 
        new_ID = 0ULL;
        if (msgLen == 12) {recChecksum = char2int(msg[i+1]) | char2int(msg[i]) << 4;}//RDM6300
        else if (msgLen == 11) {recChecksum = (uint8_t)msg[i];}                      //RF125-PS
        tagtype = 2;
    }
    if (checksum != recChecksum) return;
    unsigned long _now = millis();
    if ((_now-LastRFID > 3000)||(tagIdValue != last_ID))
    {
        new_ID = tagIdValue;
        last_ID = tagIdValue;
        data_available = true;
        LastRFID = _now;
    }
}