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I am using nRF24L01 to communicate between two micro controllers. Both are Arduino Uno.

The question i have here is , even if i do not send any data from sender to receiver , the receiver device is constantly checking for the data, and the blank data is being received per second. And also no data is received by receiver which is sent by sender.

I am sharing the code for both sender and receiver.

Please suggest me what wrong i am doing.

Receiver Code :

#include <SPI.h>
#include <nRF24L01.h>
#include <RF24.h>

RF24 radio(7, 8); // CNS, CE
String response;
boolean done = false;

void setup() {

 delay(500);
 Serial.begin(9600);

 radio.begin();
 radio.setPALevel(RF24_PA_MIN);
 radio.openReadingPipe(0, 0xF0F0F0F0AA);
 radio.startListening();

}

void loop() {

   if (radio.available()) {

   radio.read(&response, sizeof(response));
   done = true;

}

if (done) {
  Serial.println(response);
}

done = false;
delay(1000);

}

Sender Code:

#include <SPI.h>
#include <nRF24L01.h>
#include <RF24.h>

RF24 radio(7, 8); // CNS, CE
String request;

void setup() {

delay(500);
Serial.begin(9600);

radio.begin();
radio.openWritingPipe(0xF0F0F0F0AA);
radio.setPALevel(RF24_PA_MIN);
radio.stopListening();

}

void loop() {

   while ( Serial.available() > 0 )  {

   request = Serial.readString();


   Serial.println(request);
   radio.write(&request, sizeof(request));

   delay(1000);

 }
}
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  • Comments are not for extended discussion; this conversation has been moved to chat.
    – Avamander
    Aug 29, 2017 at 14:05

2 Answers 2

Reset to default
1

I've written a code for NRF24L01+ based on the datasheet.run them on your arduino and test them.CE pin is PIN7 in arduino and CSN is PIN8 in arduino. NRF_monitorRegisters() shows all Registers of NRF.It's nice to test your NRF maybe it helps:

for transmitter:

#include <SPI.h>

int sending = 1;
int data = 7;

void IRQ() {
  Serial.println("STATUS register from IRQ ISR :  ");
  digitalWrite(8, 0);
  SPI.transfer(0x07);
  delay(10);
  Serial.println(SPI.transfer(0xff), BIN);
  delay(10);
  digitalWrite(8, 1);

  digitalWrite(8, 0);
  SPI.transfer(0x08);
  delay(10);
  Serial.println(SPI.transfer(0xff), BIN);
  delay(10);
  digitalWrite(8, 1);

  digitalWrite(8, 0);
  SPI.transfer(0x07 + 0x20);
  delay(10);
  SPI.transfer(0xff);
  delay(10);
  digitalWrite(8, 1);
}


void NRF_transmitterBegin() {

  //reading
  /*digitalWrite(8, 0);
    SPI.transfer(0x00);
    delay(10);
    Serial.println(SPI.transfer(0xff), BIN);
    delay(10);
    digitalWrite(8, 1);*/

  pinMode(7, OUTPUT);  //CE
  pinMode(8, OUTPUT);  //CSN
  delay(100);
  digitalWrite(8, 1);
  digitalWrite(7, 0);

  SPI.setBitOrder(MSBFIRST);
  SPI.setDataMode(SPI_MODE0);
  SPI.setClockDivider(SPI_CLOCK_DIV4);
  SPI.begin();
  delay(1000);


  digitalWrite(8, 0);   //flush TX_FIFO
  SPI.transfer(0xe1);
  delay(10);
  digitalWrite(8, 1);


  digitalWrite(8, 0);   //flush RX_FIFO
  SPI.transfer(0xe2);
  delay(10);
  digitalWrite(8, 1);


  digitalWrite(8, 0);
  SPI.transfer(0x07 + 0x20);
  delay(10);
  SPI.transfer(0xf0);
  delay(10);
  digitalWrite(8, 1);


  digitalWrite(8, 0);
  SPI.transfer(0x00 + 0x20);
  delay(10);
  SPI.transfer(0x0e);
  delay(10);
  digitalWrite(8, 1);
  delay(10);


  /*digitalWrite(8, 0);
    SPI.transfer(0x11 + 0x20);
    delay(10);
    SPI.transfer(0x3f);
    delay(10);
    digitalWrite(8, 1);*/


  //Down for DYNPL
  digitalWrite(8, 0);
  SPI.transfer(0x1c + 0x20);
  delay(10);
  SPI.transfer(0x01);
  delay(10);
  digitalWrite(8, 1);


  digitalWrite(8, 0);
  SPI.transfer(0x1d + 0x20);
  delay(10);
  SPI.transfer(0x04);
  delay(10);
  digitalWrite(8, 1);
  //Up for DYNPL


  digitalWrite(8, 0);
  SPI.transfer(0x01 + 0x20);
  delay(10);
  SPI.transfer(0x3f);
  delay(10);
  digitalWrite(8, 1);


  digitalWrite(8, 0);
  SPI.transfer(0x02 + 0x20);
  delay(10);
  SPI.transfer(0x03);
  delay(10);
  digitalWrite(8, 1);


  digitalWrite(8, 0);
  SPI.transfer(0x03 + 0x20);
  delay(10);
  SPI.transfer(0x03);
  delay(10);
  digitalWrite(8, 1);


  digitalWrite(8, 0);
  SPI.transfer(0x04 + 0x20);
  delay(10);
  SPI.transfer(0xff);
  delay(10);
  digitalWrite(8, 1);


  digitalWrite(8, 0);
  SPI.transfer(0x05 + 0x20);
  delay(10);
  SPI.transfer(0x4c);
  delay(10);
  digitalWrite(8, 1);


  digitalWrite(8, 0);
  SPI.transfer(0x06 + 0x20);
  delay(10);
  SPI.transfer(0x06);
  delay(10);
  digitalWrite(8, 1);


  digitalWrite(8, 0);
  SPI.transfer(0x0a + 0x20);
  delay(10);
  SPI.transfer(0xaa);
  delay(10);
  SPI.transfer(0xaa);
  delay(10);
  SPI.transfer(0xaa);
  delay(10);
  SPI.transfer(0xaa);
  delay(10);
  SPI.transfer(0xaa);
  delay(10);
  digitalWrite(8, 1);


  digitalWrite(8, 0);
  SPI.transfer(0x10 + 0x20);
  delay(10);
  SPI.transfer(0xaa);
  delay(10);
  SPI.transfer(0xaa);
  delay(10);
  SPI.transfer(0xaa);
  delay(10);
  SPI.transfer(0xaa);
  delay(10);
  SPI.transfer(0xaa);
  delay(10);
  digitalWrite(8, 1);


  attachInterrupt(digitalPinToInterrupt(2), IRQ, FALLING);
  delay(10);

}

void NRF_transmit(int whatIsData , float data , float hum) {    //hum is used just for temp&humidity
  /*
     byte 0 says what is our data:  1 -> data and humidity    2 -> movement   3 -> gas

     1(float) :   byte 1 -> integer part of temp  byte 2 -> fractional part of temp   byte 3 -> integer part of humidity    byte 4 -> fractional part of humidity    byte 5 -> %battery
     2(binary) :  byte 1 -> %battery
     3(float) :   byte 1 -> integer part of gas   byte 2 -> fractional part of gas    byte 3 -> %battery

     %battery feature is in progress ...
  */

  int byte0 = 0 , byte1 = 0 , byte2 = 0 , byte3 = 0 , byte4 = 0 , byte5 = 0;
  float buf = 0;

  byte0 = whatIsData;

  switch (whatIsData) {
    case 1: {

        byte1 = data;
        buf = data - byte1;
        byte2 = buf * 10;

        byte3 = hum;
        buf = hum - byte3;
        byte4 = buf * 10;

        break;
      }
    case 2: {

        break;
      }
    case 3: {

        byte1 = data;
        buf = data - byte1;
        byte2 = buf * 10;

        break;
      }
    default: {
        break;
      }
  }

  digitalWrite(8, 0);
  SPI.transfer(0xe1);   //flush TX_FIFO empty
  delay(10);
  digitalWrite(8, 1);

  digitalWrite(8, 0);
  SPI.transfer(0xa0);   //write on TX_FIFO
  delay(10);
  SPI.transfer(byte0);
  delay(10);
  SPI.transfer(byte1);
  delay(10);
  SPI.transfer(byte2);
  delay(10);
  SPI.transfer(byte3);
  delay(10);
  SPI.transfer(byte4);
  delay(10);
  SPI.transfer(byte5);
  delay(10);
  digitalWrite(8, 1);

  digitalWrite(7, 1);   //CE High
  delay(1);
  digitalWrite(7, 0);   //CE Low

}


void NRF_monitorRegisters() {

  for (int i = 0; i < 30; i++) {
    digitalWrite(8, 0);
    SPI.transfer(i);
    delay(10);
    Serial.print(i , HEX);
    Serial.print(" -> ");
    Serial.println(SPI.transfer(0xff), BIN);
    delay(10);
    digitalWrite(8, 1);
  }
  Serial.println("");

}


void setup() {

  Serial.begin(115200);

  NRF_transmitterBegin();
  NRF_monitorRegisters();

}

void loop() {

  NRF_transmit(3 , 15.1 , 0);

  delay(1000);
}

for receiver :

#include <SPI.h>

long int lastTime = 0;

void IRQ() {

  int whatIsData = 0;
  int byte1 = 0 , byte2 = 0 , byte3 = 0 , byte4 = 0 , byte5 = 0;
  float data = 0 , hum = 0 , buf = 0;

  /*Serial.println("STATUS register from IRQ ISR :  ");
    digitalWrite(8, 0);
    SPI.transfer(0x07);
    delay(10);
    Serial.println(SPI.transfer(0xff), BIN);
    delay(10);
    digitalWrite(8, 1);*/

  digitalWrite(8, 0);
  SPI.transfer(0x61);
  delay(10);
  whatIsData = SPI.transfer(0xff);
  delay(10);
  byte1 = SPI.transfer(0xff);
  delay(10);
  byte2 = SPI.transfer(0xff);
  delay(10);
  byte3 = SPI.transfer(0xff);
  delay(10);
  byte4 = SPI.transfer(0xff);
  delay(10);
  byte5 = SPI.transfer(0xff);
  delay(10);
  digitalWrite(8, 1);

  digitalWrite(8, 0);   //flush RX_FIFO
  SPI.transfer(0xe2);
  delay(10);
  digitalWrite(8, 1);

  digitalWrite(8, 0);
  SPI.transfer(0x07 + 0x20);
  delay(10);
  SPI.transfer(0xf0);
  delay(10);
  digitalWrite(8, 1);
  delay(10);


  switch (whatIsData) {
    case 1: {

        buf = byte2;
        data = byte1 + buf / 10;
        buf = byte4;
        hum = byte3 + buf / 10;

        Serial.print("Received data from DHT22 -> temp:");
        Serial.print(data);
        Serial.print("  humidity:");
        Serial.println(hum);

        break;
      }
    case 2: {

        Serial.println("Received data from PIR -> Move detected");

        break;
      }
    case 3: {

        buf = byte2;
        data = byte1 + buf / 10;

        Serial.print("Received data from gas sensor -> %gas:");
        Serial.println(data);

        break;
      }
    default: {

        Serial.println("a problem accured");

        break;
      }
  }

}

void NRF_receiverBegin() {

  //reading
  /*digitalWrite(8, 0);
    SPI.transfer(0x00);
    delay(10);
    Serial.println(SPI.transfer(0xff), BIN);
    delay(10);
    digitalWrite(8, 1);*/

  pinMode(7, OUTPUT);  //CE
  pinMode(8, OUTPUT);  //CSN
  delay(100);
  digitalWrite(8, 1);
  digitalWrite(7, 0);

  SPI.setBitOrder(MSBFIRST);
  SPI.setDataMode(SPI_MODE0);
  SPI.setClockDivider(SPI_CLOCK_DIV4);
  SPI.begin();
  delay(100);

  digitalWrite(8, 0);   //flush TX_FIFO
  SPI.transfer(0xe1);
  delay(10);
  digitalWrite(8, 1);

  digitalWrite(8, 0);   //flush RX_FIFO
  SPI.transfer(0xe2);
  delay(10);
  digitalWrite(8, 1);

  digitalWrite(8, 0);
  SPI.transfer(0x07 + 0x20);
  delay(10);
  SPI.transfer(0xf0);
  delay(10);
  digitalWrite(8, 1);
  delay(10);

  digitalWrite(8, 0);
  SPI.transfer(0x00 + 0x20);
  delay(10);
  SPI.transfer(0x0f);
  delay(10);
  digitalWrite(8, 1);
  delay(10);

  /*digitalWrite(8, 0);
    SPI.transfer(0x11 + 0x20);
    delay(10);
    SPI.transfer(0x01);
    delay(10);
    digitalWrite(8, 1);*/

  //Down for DYNPL
  digitalWrite(8, 0);
  SPI.transfer(0x1c + 0x20);
  delay(10);
  SPI.transfer(0x01);
  delay(10);
  digitalWrite(8, 1);


  digitalWrite(8, 0);
  SPI.transfer(0x1d + 0x20);
  delay(10);
  SPI.transfer(0x04);
  delay(10);
  digitalWrite(8, 1);
  //Up for DYNPL


  digitalWrite(8, 0);
  SPI.transfer(0x01 + 0x20);
  delay(10);
  SPI.transfer(0x3f);
  delay(10);
  digitalWrite(8, 1);


  digitalWrite(8, 0);
  SPI.transfer(0x02 + 0x20);
  delay(10);
  SPI.transfer(0x03);
  delay(10);
  digitalWrite(8, 1);


  digitalWrite(8, 0);
  SPI.transfer(0x03 + 0x20);
  delay(10);
  SPI.transfer(0x03);
  delay(10);
  digitalWrite(8, 1);


  digitalWrite(8, 0);
  SPI.transfer(0x04 + 0x20);
  delay(10);
  SPI.transfer(0xff);
  delay(10);
  digitalWrite(8, 1);


  digitalWrite(8, 0);
  SPI.transfer(0x05 + 0x20);
  delay(10);
  SPI.transfer(0x4c);
  delay(10);
  digitalWrite(8, 1);


  digitalWrite(8, 0);
  SPI.transfer(0x06 + 0x20);
  delay(10);
  SPI.transfer(0x06);
  delay(10);
  digitalWrite(8, 1);


  digitalWrite(8, 0);
  SPI.transfer(0x0a + 0x20);
  delay(10);
  SPI.transfer(0xaa);
  delay(10);
  SPI.transfer(0xaa);
  delay(10);
  SPI.transfer(0xaa);
  delay(10);
  SPI.transfer(0xaa);
  delay(10);
  SPI.transfer(0xaa);
  delay(10);
  digitalWrite(8, 1);


  digitalWrite(8, 0);
  SPI.transfer(0x10 + 0x20);
  delay(10);
  SPI.transfer(0xaa);
  delay(10);
  SPI.transfer(0xaa);
  delay(10);
  SPI.transfer(0xaa);
  delay(10);
  SPI.transfer(0xaa);
  delay(10);
  SPI.transfer(0xaa);
  delay(10);
  digitalWrite(8, 1);

}


void NRF_startListening() {

  attachInterrupt(digitalPinToInterrupt(2), IRQ, FALLING);

  digitalWrite(7, 1);   //CE High
  Serial.println("Listening started");

}


void NRF_monitorRegisters() {

  for (int i = 0; i < 30; i++) {
    digitalWrite(8, 0);
    SPI.transfer(i);
    delay(10);
    Serial.print(i , HEX);
    Serial.print(" -> ");
    Serial.println(SPI.transfer(0xff), BIN);
    delay(10);
    digitalWrite(8, 1);
  }
  Serial.println("");

}

void setup() {

  Serial.begin(115200);

  NRF_receiverBegin();
  NRF_startListening();
  NRF_monitorRegisters();

}


void loop() {

  /*if (millis() - lastTime > 20000) {
    NRF_monitorRegisters();
    lastTime = millis();
  }*/

}
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  • Please, explain the how's and why's of your answer.
    – user31481
    Jan 21, 2018 at 15:59
  • 1
    OK.if u read Datasheet u'll found that NRF communicates with MCU by SPI. and u can control the NRF by it's registers. in page 48 of NORDIC Datasheet u can see all commands of NRF (for example u can write on a register with 001A AAAA witch AAAAA is address of register and in next step u'll write the registers value.) and in page 54 u can see the registers address.
    – amin
    Jan 21, 2018 at 16:09
  • You answer may be correct, but I learnt nothing from it. I only got two sketches, one that works; the other, no. Why one and not the other? I don't know; no explanation given.
    – user31481
    Jan 21, 2018 at 16:39
0

You may have reversed the wire:

RF24 radio(7, 8); //  CE,CNS
Improve this answer
1
  • This could be a valid comment towards an answer, but it needs more explanation. Perhaps your theory is that by not properly enabling the chip, the idle state of MISO is being read and misinterpreted as the status register showing data available. But if that is your theory, you need to actually state it, not just leave a cryptic mention of wiring.
    – Chris Stratton
    Jan 20, 2018 at 17:43

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