Static Wireless Sensor Network with Arduino NRF24l01

Hi,
   Right from my childhood I wanted to control appliances and had an eye for Automation
may be I'm just too lazy , two years back I wrote the software for this !

Video of my WSN NRF24L01+Arduino
code is somewhat like this .

NRF24L01 packet

class packet {
  public :
    unsigned char  frame_type; // data or synchronization 
    unsigned short int to_add; // packet destination address
    unsigned short int from_add; // packet origin address 
    unsigned short int h_from_add; // packet immediate hopped address
    unsigned short int frame;          // packet send on frame 
    unsigned long data1;                 // data holder
};


Arduino setup function , here were are setting up nrf24l01/serial/ZCD .

void setup()
{
  if ( cid == 0 ) {
    pinMode(2, OUTPUT);
  } else {
    pinMode(2,INPUT);
  }
  
  pinMode(DETECT, INPUT);     //zero cross detect
  digitalWrite(DETECT, HIGH); //enable pull-up resistor
  pinMode(GATE, OUTPUT);      //triac gate control

  Serial.begin(57600);

  while (!Serial) ;
  Serial.println("start ");

  if (!nrf24.init())
    Serial.println("NRF24 init failed");
    
  if (!nrf24.setChannel(B_Freq))
    Serial.println("setChannel failed");

   mask1 = mask | cid;
   if (!nrf24.setThisAddress((uint8_t*)(&mask1), 5))
     Serial.println("setThisAddress failed");

  if (!nrf24.setPayloadSize(len))
    Serial.println("setPayloadSize failed");

  if (!nrf24.setRF(NRF24::NRF24DataRate2Mbps, NRF24::NRF24TransmitPower0dBm))
    Serial.println("setRF failed");    

    ping_s = 0;
    cnt =0;
    frame = 150;
    route_packet = 0;
    route_pac_delay = 0;
    num_retries = 0 ;
    b_cnt = 0;
    data.h_from_add = cid ;

    data.frame_type = 0;
    noInterrupts();           // disable all interrupts
    TCCR1A = 0;
    TCCR1B = 0;
    TCNT1  = 0;

    OCR1A = 30000;            // compare match register 16MHz/256/2Hz
    TCCR1B |= (1 << WGM12);   // CTC mode
    TCCR1B |= (1 << CS11);    // 256 prescaler 
    TIMSK1 |= (1 << OCIE1A);  // enable timer compare interrupt
    interrupts();             // enable all interrupts 
    
    if ( cid == 0 )  {
          is_sync = 1;
    } else {
          is_sync = 0;
    }
    randomSeed(cid*10);
    b_cnt = random(200,500);
    
    ping_timeout=random(200,500);
    ping_retries=0;
    
    Serial.print("Curr ID ");
    Serial.println(data.h_from_add,DEC);
    attachInterrupt(1,zeroCrossingInterrupt, CHANGE );
}

Below Function will send data to next hop address based on routing table .

bool route_data () {

    routed = 0 ;

    for ( cnt = 0 ; cnt <= luk_len ; cnt ++ ) {

if ( (data.to_add >= luk_tab[cnt][0] && data.to_add <= luk_tab[cnt][1] ) ) {

                      routed = 1;

if ( cnt == luk_len ) {

send_to(up_link);

} else {

       send_to(luk_tab[cnt][0]);

}

                        break ;

if ( routed == 1 ) {

break ;

}

      }

   }

      

   if ( routed == 0 || routed != 1 ) {

// NOT ABLE TO SEND THE data .

   }

   return (routed==1) ;

}

Actual function which will send data via NRF24L01 , it will also select frequency based on to_address and frame number .

bool send_to (unsigned short int to_addr ) {

        if ( b_flag == 0 ) {

        f  = to_addr * 11117 + ( frame *31 ) ;

         f = (f/13) % 11 ;

                f = (f * 10) +1 ;

        } else {

                f = B_Freq;

        }

                

        if (!nrf24.setChannel(f))

          Serial.println("setChannel failed");

        

mask1 = mask | to_addr ;

  if (!nrf24.setTransmitAddress((uint8_t*)(&mask1), 5)) {

  Serial.println("setTransmitAddress failed");

routed = 2; 

}

        delayMicroseconds(700);

       

        if ( b_flag == 1 ) {

          data.frame = frame;

          rtt = TCNT1;

          data.data1 = rtt + 1700 ;

          data.frame_type = 3;

        }

        data.h_from_add = cid;       

        if ( debug == 1 && data.frame_type == 2) {

          Serial.print(to_addr,DEC);

          Serial.print(" to add ,S'dg ");

          Serial.print(data.data1,DEC);

          Serial.print(" frame is ");

          Serial.println(frame,DEC);

        }

        if (!nrf24.send((uint8_t*)&data, sizeof(data),b_flag)) {

            Serial.println("E4"); 

   routed = 3;

}

        

        if (!nrf24.waitPacketSent()) {

          Serial.print("Sndg Fail ");

 routed = 4;

        }

        return ( routed == 1 || b_flag ) ;

}

Receiver function , configures NRF24L01 in RX mode and selects frequency based on same formula used in TX mode .

bool listen_rx() {

  f  = cid * 11117 + ( frame *31 );

  f = (f/13) % 11 ;

  f = (f * 10) +1 ;

  nrf24.powerUpRx();

  if (!nrf24.setChannel(f))

     Serial.println("setChannel failed");

   if (nrf24.waitAvailableTimeout(5)) {

          if (!nrf24.recv((uint8_t*)&data_junk, &len)) {

            Serial.println("read failed");

   return 0;

 }

       if ( debug == 1 && data_junk.frame_type==2) {

          if ( serial_read == 'A' ) {

             trigger_delay = data_junk.data1 -65 ;

             Serial.print("setting val ");

             Serial.println(trigger_delay , DEC );        

          }

          Serial.print(data_junk.h_from_add,DEC);

          Serial.print(" rx from add ,S'dg ");

          serial_read = data_junk.data1;

          Serial.print(serial_read,DEC);

          Serial.print(" frame is ");

          Serial.println(frame,DEC);

          

        }

        

        if ( data_junk.frame_type == 2 && data_junk.to_add != cid) {

            data_in=data_junk;

            route_packet =1;

            route_pac_delay = random(2,8);

            num_retries = 0 ; 

        }

   }

  return 1;

}

Function used for synchronizing two nodes , received beacon packet will have counter value which is used to load into TCNT1 of received node .

void sync_me (bool ip) {

 

        nrf24.powerUpRx();

        if (!nrf24.setChannel(B_Freq))

  Serial.println("setChannel failed");

          

        mask1 = mask | up_link ;

        

        if (!nrf24.setTransmitAddress((uint8_t*)(&mask1), 5))

    Serial.println("setTransmitAddress failed");

         if ( ip == 1)  {

         }

         if ( ip == 1 ) {

             TCCR1B &= ~(1 << CS11);    // stop counter

    nrf24.waitAvailable() ;

             TCCR1B |= (1 << CS11);    // start counter

         } 

if (!nrf24.recv((uint8_t*)&data, &len))

 Serial.println("read failed");

        

TCNT1 = data.data1 - 500;

frame = data.frame;

mask1 = mask | data.h_from_add ;

is_sync =1; 

        nrf24.setTransmitAddress((uint8_t*)"NULL1", 5);

  

}

Function used to send beacon packet for slave nodes 

void send_beacon () {

 // Serial.print("Send beac ");

 //  Serial.println(frame,DEC);

   b_flag = 1;

   send_to(cid);

   b_flag = 0;

   b_cnt = random(300,600);

}

Function calling route_data() and from there send_to() .

void send_packet () {

  //Serial.println("send pack");

  data=data_in;

  data.frame_type =2;

  if ( ! route_data() ) {

num_retries++;

if ( num_retries > 10 ) {

                         Serial.println("Droping pack");

route_packet =0 ;

num_retries = 0 ;

}

} else {

route_packet = 0;

num_retries = 0 ;

}

route_pac_delay = random(5,15);

data.frame_type = 0;

}

MISC functions used for book keeping

bool process_state () {

  while ( ping_s == 0 ) {delayMicroseconds(1);}

  ping_s = 0 ;

  frame= frame+1 ;

  if ( frame > 150 ) {frame = 0;}

}

bool post_processing () {

// nrf24.powerDown();

if ( route_pac_delay > 0 ) {

  route_pac_delay--;

}

 b_cnt ++ ;

 ping_timeout++ ;

}

Functional loop used to send/receive/synchronize nodes .

void loop() {

 loop_var = 10;

 

 process_state();

 

 if ( cid == 0 ) {

   digitalWrite(2,HIGH); 

   digitalWrite(2,LOW); 

 }

 

     

 if ( is_sync == 0 ) {

    loop_var = 3;

   sync_me(1);

   Serial.println("sync'd");

 } else if ((cid+2) == frame  ) {

    loop_var = 4;

    send_beacon();

 }  else if ( (up_link+2)==frame ) {

    loop_var = 5;

       sync_me(0);

 } else if (route_packet == 1 && route_pac_delay == 0) {

    loop_var = 6;

      send_packet();

 } else if (route_packet == 0 && Serial.available()) {

      loop_var = 7;

     Serial.println(max_tcnt,DEC);

      data_in.data1 = Serial.read(); ;

      data_in.to_add = ping_node ;

      data_in.from_add = cid ;

      route_packet =1;

      num_retries = 0 ;

 } else {

    loop_var = 8;

    listen_rx();

 }

 nrf24.setTransmitAddress((uint8_t*)"NULL1", 5);

 post_processing();

 if ( ping_s == 1  ) {

   Serial.print("Error ");

   Serial.println(loop_var,DEC);

 //  delay(100000);

 }

}

I'll update more information and few pictures explaining how routing between nodes work .