LwRx.cpp

// LwRx.cpp
//
// LightwaveRF 434MHz receiver interface for Arduino
// 
// Author: Bob Tidey (robert@tideys.net)

#include "LwRx.h"

static const byte rx_nibble[] = {0xF6,0xEE,0xED,0xEB,0xDE,0xDD,0xDB,0xBE,0xBD,0xBB,0xB7,0x7E,0x7D,0x7B,0x77,0x6F};
static const byte rx_cmd_off     = 0xF6; // raw 0
static const byte rx_cmd_on      = 0xEE; // raw 1
static const byte rx_cmd_mood    = 0xED; // raw 2
static const byte rx_par0_alloff = 0x7D; // param 192-255 all off (12 in msb)
static const byte rx_dev_15      = 0x6F; // device 15

static int rx_pin = 2;
static const byte rx_msglen = 10; // expected length of rx message

//Receive mode constants and variables
static byte rx_msg[rx_msglen]; // raw message received
static byte rx_buf[rx_msglen]; // message buffer during reception

static unsigned long rx_prev; // time of previous interrupt in microseconds

static boolean rx_msgcomplete = false; //set high when message available
static boolean rx_translate = true; // Set false to get raw data

static byte rx_state = 0;
static const byte rx_state_idle = 0;
static const byte rx_state_msgstartfound = 1;
static const byte rx_state_bytestartfound = 2;
static const byte rx_state_getbyte = 3;

static byte rx_num_bits = 0; // number of bits in the current byte
static byte rx_num_bytes = 0; // number of bytes received 

//Pairing data
static byte rx_paircount = 0;
static byte rx_pairs[rx_maxpairs][8];
static byte rx_pairtimeout = 0; // 100msec units
//set false to responds to all messages if no pairs set up
static boolean rx_pairEnforce = false;
//set false to use Address, Room and Device in pairs, true just the Address part
static boolean rx_pairBaseOnly = false;

// Repeat filters
static byte rx_repeats = 2; //msg must be repeated at least this number of times
static byte rx_repeatcount = 0;
static byte rx_timeout = 20; //reset repeat window after this in 100mSecs
static unsigned long rx_prevpkttime = 0; //last packet time in milliseconds
static unsigned long rx_pairstarttime = 0; //last msg time in milliseconds

// Gather stats for pulse widths (ave is x 16)
static const uint16_t lwrx_statsdflt[rx_stat_count] = {5000,0,5000,20000,0,2500,4000,0,500};	//usigned int
static uint16_t lwrx_stats[rx_stat_count];	//unsigned int
static boolean lwrx_stats_enable = true;

/**
  Pin change interrupt routine that identifies 1 and 0 LightwaveRF bits
  and constructs a message when a valid packet of data is received.
**/
void rx_process_bits() { 
   byte event = digitalRead(rx_pin); // start setting event to the current value
   unsigned long curr = micros(); // the current time in microseconds

   uint16_t dur = (curr-rx_prev);	//unsigned int
   rx_prev = curr;
   //set event based on input and duration of previous pulse
   if(dur < 120) { //120 very short
   } else if(dur < 500) { // normal short pulse
      event +=2;
   } else if(dur < 2000) { // normal long pulse
      event +=4;
   } else if(dur > 5000){ // gap between messages
      event +=6;
   } else { //2000 > 5000
      event = 8; //illegal gap
   } 
   //state machine transitions 
   switch(rx_state) {
      case rx_state_idle:
         switch(event) {
           case 7: //1 after a message gap
             rx_state = rx_state_msgstartfound;
             break;
         }
         break;
      case rx_state_msgstartfound:
         switch(event) {
            case 2: //0 160->500
             //nothing to do wait for next positive edge
               break;
            case 3: //1 160->500
               rx_num_bytes = 0;
               rx_state = rx_state_bytestartfound;
               break;
            default:
               //not good start again
               rx_state = rx_state_idle;
               break;
         }
         break;
      case rx_state_bytestartfound:
         switch(event) {
            case 2: //0 160->500
               //nothing to do wait for next positive edge
               break;
            case 3: //1 160->500
               rx_state = rx_state_getbyte;
               rx_num_bits = 0;
               break;
            case 5: //0 500->1500
               rx_state = rx_state_getbyte;
               // Starts with 0 so put this into byte
               rx_num_bits = 1;
               rx_buf[rx_num_bytes] = 0;
               break;
            default: 
               //not good start again
               rx_state = rx_state_idle;
               break;
         }
         break;
      case rx_state_getbyte:
         switch(event) {
            case 2: //0 160->500
               //nothing to do wait for next positive edge but do stats
               if(lwrx_stats_enable) {
                  lwrx_stats[rx_stat_high_max] = max(lwrx_stats[rx_stat_high_max], dur);
                  lwrx_stats[rx_stat_high_min] = min(lwrx_stats[rx_stat_high_min], dur);
                  lwrx_stats[rx_stat_high_ave] = lwrx_stats[rx_stat_high_ave] - (lwrx_stats[rx_stat_high_ave] >> 4) + dur;
               }
               break;
            case 3: //1 160->500
               // a single 1
               rx_buf[rx_num_bytes] = rx_buf[rx_num_bytes] << 1 | 1;
               rx_num_bits++;
               if(lwrx_stats_enable) {
                  lwrx_stats[rx_stat_low1_max] = max(lwrx_stats[rx_stat_low1_max], dur);
                  lwrx_stats[rx_stat_low1_min] = min(lwrx_stats[rx_stat_low1_min], dur);
                  lwrx_stats[rx_stat_low1_ave] = lwrx_stats[rx_stat_low1_ave] - (lwrx_stats[rx_stat_low1_ave] >> 4) + dur;
               }
               break;
            case 5: //1 500->1500
               // a 1 followed by a 0
               rx_buf[rx_num_bytes] = rx_buf[rx_num_bytes] << 2 | 2;
               rx_num_bits++;
               rx_num_bits++;
               if(lwrx_stats_enable) {
                  lwrx_stats[rx_stat_low0_max] = max(lwrx_stats[rx_stat_low0_max], dur);
                  lwrx_stats[rx_stat_low0_min] = min(lwrx_stats[rx_stat_low0_min], dur);
                  lwrx_stats[rx_stat_low0_ave] = lwrx_stats[rx_stat_low0_ave] - (lwrx_stats[rx_stat_low0_ave] >> 4) + dur;
               }
               break;
            default:
               //not good start again
               rx_state = rx_state_idle;
               break;
         }
         if(rx_num_bits >= 8) {
            rx_num_bytes++;
            rx_num_bits = 0;
            if(rx_num_bytes >= rx_msglen) {
               unsigned long currMillis = millis();
               if(rx_repeats > 0) {
                  if((currMillis - rx_prevpkttime) / 100 > rx_timeout) { 
                     rx_repeatcount = 1;
                  } else {
                     //Test message same as last one
                     int16_t i = rx_msglen;	//int
                     do {
                        i--;
                     }
                     while((i >= 0) && (rx_msg[i] == rx_buf[i]));
                     if(i < 0) {
                        rx_repeatcount++;
                     } else {
                        rx_repeatcount = 1;
                     }
                  }
               } else {
                  rx_repeatcount = 0;
               }
               rx_prevpkttime = currMillis;
               //If last message hasn't been read it gets overwritten
               memcpy(rx_msg, rx_buf, rx_msglen); 
               if(rx_repeats == 0 || rx_repeatcount == rx_repeats) {
                  if(rx_pairtimeout != 0) {
                     if((currMillis - rx_pairstarttime) / 100 <= rx_pairtimeout) {
                        if(rx_msg[3] == rx_cmd_on) {
                           rx_addpairfrommsg();
                        } else if(rx_msg[3] == rx_cmd_off) {
                           rx_removePair(&rx_msg[2]);
                        }
                     }
                  }
                  if(rx_reportMessage()) {
                     rx_msgcomplete = true;
                  }
                  rx_pairtimeout = 0;
               }
               // And cycle round for next one
               rx_state = rx_state_idle;
            } else {
              rx_state = rx_state_bytestartfound;
            }
         }
         break;
   }
}

/**
  Test if a message has arrived
**/
boolean lwrx_message() {
   return (rx_msgcomplete);
}

/**
  Set translate mode
**/
void lwrx_settranslate(boolean rxtranslate) {
   rx_translate = rxtranslate;
}

/**
  Transfer a message to user buffer
**/
boolean lwrx_getmessage(byte *buf, byte len) {
   boolean ret = true;
   int16_t j=0,k=0;		//int
   if(rx_msgcomplete && len <= rx_msglen) {
      for(byte i=0; ret && i < rx_msglen; i++) {
         if(rx_translate || (len != rx_msglen)) {
            j = rx_findNibble(rx_msg[i]);
            if(j<0) ret = false;
         } else {
            j = rx_msg[i];
         }
         switch(len) {
            case 4:
               if(i==9) buf[2]=j;
               if(i==2) buf[3]=j;
            case 2:
               if(i==3) buf[0]=j;
               if(i==0) buf[1]=j<<4;
               if(i==1) buf[1]+=j;
               break;
            case 10:
               buf[i]=j;
               break;
         }
      }
      rx_msgcomplete= false; 
   } else {
      ret = false;
   }
   return ret;
}

/**
  Return time in milliseconds since last packet received
**/
unsigned long lwrx_packetinterval() {
   return millis() - rx_prevpkttime;
}

/**
  Set up repeat filtering of received messages
**/
void lwrx_setfilter(byte repeats, byte timeout) {
   rx_repeats = repeats;
   rx_timeout = timeout;
}

/**
  Add a pair to filter received messages
  pairdata is device,dummy,5*addr,room
  pairdata is held in translated form to make comparisons quicker
**/
byte lwrx_addpair(byte* pairdata) {
   if(rx_paircount < rx_maxpairs) {
      for(byte i=0; i<8; i++) {
         rx_pairs[rx_paircount][i] = rx_nibble[pairdata[i]];
      }
      rx_paircommit();
   }
   return rx_paircount;
}

/**
  Make a pair from next message successfully received
**/
extern void lwrx_makepair(byte timeout) {
   rx_pairtimeout = timeout;
   rx_pairstarttime = millis();
}

/**
  Get pair data (translated back to nibble form
**/
extern byte lwrx_getpair(byte* pairdata, byte pairnumber) {
   if(pairnumber < rx_paircount) {
      int16_t j;	//int
      for(byte i=0; i<8; i++) {
         j = rx_findNibble(rx_pairs[pairnumber][i]);
         if(j>=0) pairdata[i] = j;
      }
   }
   return rx_paircount;
}

/**
  Clear all pairing
**/
extern void lwrx_clearpairing() {
   rx_paircount = 0;
#if EEPROM_EN
   EEPROM.write(EEPROMaddr, 0);
#endif
}

/**
  Return stats on high and low pulses
**/
boolean lwrx_getstats(uint16_t *stats) {	//unsigned int
   if(lwrx_stats_enable) {
      memcpy(stats, lwrx_stats, 2 * rx_stat_count);
      return true;
   } else {
      return false;
   }
}

/**
  Set stats mode
**/
void lwrx_setstatsenable(boolean rx_stats_enable) {
   lwrx_stats_enable = rx_stats_enable;
   if(!lwrx_stats_enable) {
      //clear down stats when disabling
      memcpy(lwrx_stats, lwrx_statsdflt, sizeof(lwrx_statsdflt));
   }
}
/**
  Set pairs behaviour
**/
void lwrx_setPairMode(boolean pairEnforce, boolean pairBaseOnly) {
   rx_pairEnforce = pairEnforce;
   rx_pairBaseOnly = pairBaseOnly;
}


/**
  Set things up to receive LightWaveRF 434Mhz messages
  pin must be 2 or 3 to trigger interrupts
  !!! For Spark, any pin will work
**/
void lwrx_setup(int pin) {
   restoreEEPROMPairing();
	rx_pin = pin;
   int int_no = getIntNo(rx_pin);
   pinMode(rx_pin,INPUT);
   attachInterrupt(int_no, rx_process_bits, CHANGE);
   memcpy(lwrx_stats, lwrx_statsdflt, sizeof(lwrx_statsdflt));
}

/**
  Check a message to see if it should be reported under pairing / mood / all off rules
  returns -1 if none found
**/
boolean rx_reportMessage() {
   if(rx_pairEnforce && rx_paircount == 0) {
      return false;
   } else {
      boolean allDevices;
      // True if mood to device 15 or Off cmd with Allof paramater
      allDevices = ((rx_msg[3] == rx_cmd_mood && rx_msg[2] == rx_dev_15) || 
                    (rx_msg[3] == rx_cmd_off && rx_msg[0] == rx_par0_alloff));
      return (rx_checkPairs(&rx_msg[2], allDevices) != -1);
   }
}
/**
  Find nibble from byte
  returns -1 if none found
**/
int16_t rx_findNibble(byte data) {	//int
   int16_t i = 15;	//int
   do {
      if(rx_nibble[i] == data) break;
      i--;
   } while (i >= 0);
   return i;
}

/**
  add pair from message buffer
**/
void rx_addpairfrommsg() {
   if(rx_paircount < rx_maxpairs) {
      memcpy(rx_pairs[rx_paircount], &rx_msg[2], 8);
      rx_paircommit();
   }
}

/**
  check and commit pair
**/
void rx_paircommit() {
   if(rx_paircount == 0 || rx_checkPairs(rx_pairs[rx_paircount], false) < 0) {
#if EEPROM_EN
		for(byte i=0; i<8; i++) {
			EEPROM.write(EEPROMaddr + 1 + 8 * rx_paircount + i, rx_pairs[rx_paircount][i]);
		}
      EEPROM.write(EEPROMaddr, rx_paircount+1);
#endif
      rx_paircount++;
   }
}

/**
  Check to see if message matches one of the pairs
    if mode is pairBase only then ignore device and room
    if allDevices is true then ignore the device number
  Returns matching pair number, -1 if not found, -2 if no pairs defined
**/
int16_t rx_checkPairs(byte *buf, boolean allDevices ) {	//int
   if(rx_paircount ==0) {
      return -2;
   } else {
      int16_t pair= rx_paircount;	//int
      int16_t j = -1;	//int
      int16_t jstart,jend;	//int
      if(rx_pairBaseOnly) {
         // skip room(8) and dev/cmd (0,1)
         jstart = 7;
         jend = 2;
      } else {
         //include room in comparison
         jstart = 8;
         //skip device comparison if allDevices true
         jend = (allDevices) ? 2 : 0;
      }
      while (pair>0 && j<0) {
         pair--;
         j = jstart;
         while(j>jend){
            j--;
            if(j != 1) {
               if(rx_pairs[pair][j] != buf[j]) {
                  j = -1;
               }
            }
         }
      }
      return (j >= 0) ? pair : -1;
   }
}

/**
  Remove an existing pair matching the buffer
**/
void rx_removePair(byte *buf) {
   int16_t pair = rx_checkPairs(buf, false);	//int
   if(pair >= 0) {
      while (pair < rx_paircount - 1) {
         for(byte j=0; j<8;j++) {
            rx_pairs[pair][j] = rx_pairs[pair+1][j];
#if EEPROM_EN
            if(EEPROMaddr >= 0) {
               EEPROM.write(EEPROMaddr + 1 + 8 * pair + j, rx_pairs[pair][j]);
            }
#endif
         }
         pair++;
      }
      rx_paircount--;
#if EEPROM_EN
      if(EEPROMaddr >= 0) {
         EEPROM.write(EEPROMaddr, rx_paircount);
      }
#endif
   }
}

/**
   Retrieve and set up pairing data from EEPROM if used
**/
void restoreEEPROMPairing() {
#if EEPROM_EN
	rx_paircount = EEPROM.read(EEPROMaddr);
	if(rx_paircount > rx_maxpairs) {
		rx_paircount = 0;
		EEPROM.write(EEPROMaddr, 0);
	} else {
		for( byte i=0; i < rx_paircount; i++) {
			for(byte j=0; j<8; j++) {
				rx_pairs[i][j] = EEPROM.read(EEPROMaddr + 1 + 8 * i + j);
			}
		}
	}
#endif
}
/**
   Get Int Number for a Pin
**/
int getIntNo(int pin) {
	int number = pin;
#ifdef PIN_NUMBERS
	int pins[8] = {PIN_NUMBERS};
	int i;
	for(i=7; i>0; i--) {
		if(pin==pins[i]) {
			break;
		}
	}
	number = i;
#endif
	return number;
}