Arduino KNX RF packet sniffer © GPL3+

#include "EEPROM.h"
#include "cc1101.h"
#include <Wire.h> 
#include <Crc16.h>

// The connection to the hardware chip CC1101 the RF Chip
CC1101 cc1101;


// a flag that a wireless packet has been received 
boolean packetAvailable = false;         
boolean crcerror = false;         
int i;
int packetcounter=0;
int packeterrorcounter=0;
byte * buffer;
int mdec;
boolean flushed=false;
byte mrcsat;  //main radio control state
byte rxbytes;
byte ecounter=0;
CCPACKET packet;
Crc16 crc; 
unsigned short crcvalue;
byte data[120];
unsigned long timer=0;
unsigned long lcdtimer=0;

void setup()
{
  SPCR &= ~_BV(SPE);  //SPI switch off
  Serial.begin(115200);
  Serial.println("start");
  
  // initialize the RF Chip
  cc1101.init();
  delay(1000);
  Serial.println("device initialized");

  Serial.println("setup done");


  //chech the configuration values writed to the radio chip. I read the radio chip out
  //if you read zero or default values the configuration is not well, check the wiring 
  for(i=0 ; i<20 ; i++) {
     Serial.print(i, HEX);
     Serial.print(":");
     Serial.print(cc1101.readReg(i, CC1101_CONFIG_REGISTER), HEX);
     Serial.print(" ");
  }

   
  Serial.println("Go...");
  cc1101.flushRxFifo();
  delay(500);
  //set radio chip to listen mode 
  cc1101.setRxState(); 
  delay(500);
  
  //and waiting for any packet
  attachInterrupt(0, cc1101signalsInterrupt, RISING);
  
}

/**
* The loop method gets called on and on after the start of the system.
*/

void readr () {
    packet.ecode=0;
    packetAvailable=false;

    byte tot=0;
    byte len;
    byte chk;
    byte chk2;
    byte pckidx=0;
    unsigned long last=0;
    do {
      last++;
      cc1101.receiveData(&packet,tot);
      
      if (packet.length>0) {
        if (tot==0) {
            //calc and set pack length
            len=cc1101.mandecode(packet.data[0]*256+packet.data[1]);
            chk=cc1101.mandecode(packet.data[2]*256+packet.data[3]);
            chk2=cc1101.mandecode(packet.data[4]*256+packet.data[5]);
            len=14+((len-9)%16)+(((len-9)/16)*18);
            len=len*2;
            if (len>100) len=100;
            if ((chk==68)&&(chk2=255)) cc1101.writeReg(0x0006, len); //Package length
            else {
                cc1101.writeReg(0x0006, 16);
                len=packet.length;
                packet.ecode=1;
                packeterrorcounter++;
                cc1101.cmdStrobe(CC1101_SIDLE);
                cc1101.cmdStrobe(CC1101_SFRX);
            }

        }
   //     Serial.print("*");
        tot=tot+packet.length;
        for(int i=0 ; i<packet.length; i++) {
           if (i%2==1) {
               data[pckidx]=cc1101.mandecode(packet.data[i-1]*256+packet.data[i]);
//               Serial.print(data[pckidx],HEX);
//               Serial.print(";");
               pckidx++;
           }
        }
      }
      delayMicroseconds(1000);
    } while ((tot<len)&&(last<100)); 
    if (tot>0) {
    packetcounter++;
    if (packet.ecode!=0) ecounter++;
    else ecounter=0;
    crcerror=false;
    Serial.print(";CRC:");
    crcvalue = crc.fastCrc(data,0,10,false,false,0x13D65,0,0,0x8000,0)^0xFFFF;
    if (crcvalue!=data[10]*256+data[11]) {Serial.print("ERROR1");crcerror=true;}
    else {
           crcvalue = crc.fastCrc(data,12,min(pckidx-14,16),false,false,0x13D65,0,0,0x8000,0)^0xFFFF;
           if (crcvalue!=data[min(pckidx-2,28)]*256+data[min(pckidx-1,29)]) {Serial.print("ERROR2");crcerror=true;}
           else {
                  if (pckidx>32) {
                      crcvalue = crc.fastCrc(data,30,min(pckidx-32,16),false,false,0x13D65,0,0,0x8000,0)^0xFFFF;
                      if (crcvalue!=data[pckidx-2]*256+data[pckidx-1]) {Serial.print("ERROR3");crcerror=true;}
                      else Serial.print("OK3");
                  } 
                  else Serial.print("OK2");
                }
         }
//    if (crcerror==false)
    {
        for(int i=0 ; i<pckidx; i++) {
               if ((i==10)||(i==11)) {;}
               else if ((i==28)||(i==29)) {;}
               else if ((i==pckidx-1)||(i==pckidx-2)) {;}
               else { 
                 Serial.print(";");
//                 if (data[i]<10) Serial.print("  ");
//                 else if (data[i]<100) Serial.print(" ");
                 Serial.print(data[i]);
               }
        }
        Serial.println(";");
    }
    if (crcerror==true) 
    {
       packeterrorcounter++;
       Serial.print("Total:");
       Serial.print(tot);
       Serial.print(";Error:");
       Serial.print(packet.ecode);
       Serial.print(";RXCount:");
       Serial.print(packet.rxcount);
       Serial.print(";Overflow:");
       Serial.print(packet.overflow);
       Serial.print(";MRCS:");
       mrcsat=cc1101.readReg(CC1101_MARCSTATE,CC1101_STATUS_REGISTER);    
       Serial.print(mrcsat);
       Serial.println(";");
    }
    if (ecounter==3) {
        Serial.println("***RESET***");
        cc1101.reset();
        delay(500);
        ecounter=0;
    } 
    cc1101.setRxState();
    cc1101.writeReg(0x0006, 100);
    }
}

void cc1101signalsInterrupt(void){
  //if it has some received byte in the fifo and reach the defined count the the chip send an interrupt to the arduino
  packetAvailable=true;
}


void loop() {
  //this is an unlimited loop
  if (packetAvailable) {
     timer=0;
     //if received some bytes i call my own read out procedure
     readr();
  } else {
     timer++;
     if (timer%100000==0) {
        //sometimes i check the chip, maybe it freezed, and sometimes need to reboot
        timer=0;

        mrcsat=cc1101.readReg(CC1101_MARCSTATE,CC1101_STATUS_REGISTER); 
  
        cc1101.cmdStrobe(CC1101_SIDLE);
        cc1101.cmdStrobe(CC1101_SFRX);
        cc1101.cmdStrobe(CC1101_SRX);
        
                
      
     }
  }


  
}