Problem with nRF24 data sending

XenuXE · January 29, 2020, 6:38pm

I want to send multiple data between 2 arduinos and i get only 0 on output pls help. I connected everything as it should be input is from joystick. When I use TransferTimeout example it transfers with no problems.

Code for transfer

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

RF24 radio(7, 8);

const byte rxAddr[6] = "00001";

  
  
typedef struct{
    int x;
    int y;
  }
  joystick;

  joystick joy;
void setup() {

  Serial.begin(9600);
  radio.begin();
  radio.setRetries(15, 100);
  radio.openWritingPipe(rxAddr);
  
  radio.stopListening();
  
}

void loop() {
  
joy.x = analogRead(A5);
  joy.y = analogRead(A4);
  radio.write( &joy, sizeof(joy) );
      radio.startListening();
      delay(200);

}

and for reciver

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

RF24 radio(7, 8);

const byte rxAddr[6] = "00001";

typedef struct{
    int x;
    int y;
    }
    joystick;
    joystick joy;
void setup() {

  Serial.begin(9600);
  radio.begin();
  radio.setRetries(15, 100);
  radio.openWritingPipe(rxAddr);
  radio.startListening();
  
}

void loop() {
  // put your main code here, to run repeatedly:
  
  radio.read( &joy, sizeof(joy) );
  Serial.print("joy.x = ");
    Serial.println(joy.x);
    Serial.print("joy.y = ");
    Serial.println(joy.y);
    delay(200);
  
}

Robin2 · January 29, 2020, 7:19pm

Have a look at this Simple nRF24L01+ Tutorial.

Wireless problems can be very difficult to debug so get the wireless part working on its own before you start adding any other features.

The examples are as simple as I could make them and they have worked for other Forum members. If you get stuck it will be easier to help with code that I am familiar with. Start by getting the first example to work

There is also a connection test program to check that the Arduino can talk to the nRF24 it is connected to.

...R

XenuXE · January 30, 2020, 11:17am

Problem in my situation is that I need to send variables. I sucessfully transfered text by myself before but i dont know how to send variables by using structure.

Danois90 · January 30, 2020, 11:30am

First you need to declare your struct right:

struct TYPENAME { struct members }; //This is right
struct { struct members } VARIABLENAME; //This is wrong

You should also make sure that the size of the payload matches the size of the message with "radio.setPayloadSize(sizeof(TYPENAME))".

Even though it not causes a problem, you should set pinMode for the analog pins before reading from them. I would also make some Serial.prints for the "joy" variable on the transmitter end to be sure that the analog reads actually produces values other than zero.

XenuXE · January 30, 2020, 11:58am

Oh thanks I'll try it later. Thanks for explaining how structure work.

UKHeliBob · January 30, 2020, 12:26pm

struct { struct members } VARIABLENAME; //This is wrong

Whilst it does not define a type is it really wrong ?

Danois90 · January 30, 2020, 1:02pm

UKHeliBob:
Whilst it does not define a type is it really wrong ?

If OP wants to use the struct as a type, which it seems like due to the "typedef" and the "joystick joy;" declarations, then I would consider it wrong. If the struct is only to be used as a single instance variable, then it is not wrong.

UKHeliBob · January 30, 2020, 2:11pm

If OP wants to use the struct as a type, which it seems like due to the "typedef"

I rather suspect that it was copied from old examples rather than being a conscious decision

XenuXE · January 30, 2020, 3:40pm

Ok so i write code

transmiter

    #include <SPI.h>  
    #include "RF24.h"
    RF24 myRadio (7, 8);

        struct package
    {
      int id=1;
      float temperature = 18.3;
      char  text[100] = "Text to be transmitted";
    };
    typedef struct package Package;
    Package data;
const byte rxAddr[6] = "00001";
    
    void setup()
    {
      Serial.begin(9600);
      delay(1000);
      myRadio.begin();  
      myRadio.setChannel(115); 
      myRadio.setPALevel(RF24_PA_MAX);
      myRadio.setDataRate( RF24_250KBPS ) ; 
      myRadio.openWritingPipe(rxAddr);
      delay(1000);
    }

        void loop()
    {
      myRadio.write(&data, sizeof(data)); 
      Serial.print("\nPackage:");
      Serial.print(data.id);
      Serial.print("\n");
      Serial.println(data.temperature);
      Serial.println(data.text);
      delay(1000);
    }

and for reciver

    #include <SPI.h>  
    #include "RF24.h"
const byte rxAddr[6] = "00001";
    RF24 myRadio (7, 8);
    struct package
    {
      int id=0;
      float temperature = 0.0;
      char  text[100] ="empty";
    };
 
    package data;
    
    byte addresses[][6] = {"0"};
    
    void setup() 
    {
      Serial.begin(9600);
      delay(1000);
      myRadio.begin(); 
      myRadio.setChannel(115); 
      myRadio.setPALevel(RF24_PA_MAX);
      myRadio.setDataRate( RF24_250KBPS ) ; 
      myRadio.openReadingPipe(1, rxAddr);
      myRadio.startListening();
    }
        void loop()  
    {
      if ( myRadio.available()) 
      {
        while (myRadio.available())
        {
          myRadio.read( &data, sizeof(data) );
        }
        Serial.print("\nPackage:");
        Serial.print(data.id);
        Serial.print("\n");
        Serial.println(data.temperature);
        Serial.println(data.text);
      }
    }

If enyone know what the hell is bad with it please write

UKHeliBob · January 30, 2020, 3:45pm

char  text[100] = "Text to be transmitted";

How many bytes can the NRF24 send with one write() command ?

XenuXE · January 30, 2020, 3:51pm

If someone can write code that can send variables I'll be happy because rly don't know what i do wrong that it doesn't work

UKHeliBob · January 30, 2020, 4:26pm

rly don't know what i do wrong that it doesn't work

How many bytes can the NRF24 send with one write() command ?

The answer is 32
How many bytes are you trying to send ?

XenuXE · January 30, 2020, 4:49pm

i know i changed that to 32 and still nothing

UKHeliBob · January 30, 2020, 4:53pm

i changed that to 32 and still nothing

If you are sending a struct then the total size of the struct must not exceed 32 bytes, not just each element of it

Post the Tx and Rx programs as they are now

XenuXE · January 30, 2020, 4:56pm

transmiter

 #include <SPI.h>  
    #include "RF24.h"
        RF24 myRadio (7, 8);
const byte rxAddr[6] = "00001";
        struct package
{
  int id=1;
  float temperature = 18.3;
  char  text[32] = "elon";
};
typedef struct package Package;
Package data;
    void setup()
    {
      Serial.begin(9600);
      delay(1000);
      myRadio.begin();  
      myRadio.setChannel(115); 
      myRadio.setPALevel(RF24_PA_MAX);
      myRadio.setDataRate( RF24_250KBPS ) ; 
      myRadio.openReadingPipe(1, rxAddr);
      delay(1000);
    }
        void loop()
    {
      myRadio.write(&data, sizeof(data)); 
      Serial.print("\nPackage:");
      Serial.print(data.id);
      Serial.print("\n");
      Serial.println(data.temperature);
      Serial.println(data.text);
      data.id = data.id + 1;
      data.temperature = data.temperature+0.1;
      delay(1000);
    }[

reciver

    #include <SPI.h>  
    #include "RF24.h"
const byte rxAddr[6] = "00001";
    RF24 myRadio (7, 8);
    struct package
    {
      int id=0;
      float temperature = 0.0;
      char  text[32] ="";
    };
 
    package data;
    
    
    void setup() 
    {
      Serial.begin(9600);
      delay(1000);
      myRadio.begin(); 
      myRadio.setChannel(115); 
      myRadio.setPALevel(RF24_PA_MAX);
      myRadio.setDataRate( RF24_250KBPS ) ; 
      myRadio.openReadingPipe(1, rxAddr);
      myRadio.startListening();
    }
        void loop()  
    {
      if ( myRadio.available()) 
      {
        while (myRadio.available())
        {
          myRadio.read( &data, sizeof(data) );
        }
        Serial.print("\nPackage:");
        Serial.print(data.id);
        Serial.print("elo");
        Serial.println(data.temperature);
        Serial.println(data.text);
      }
    }

gfvalvo · January 30, 2020, 5:25pm

struct package
{
  int id = 1;
  float temperature = 18.3;
  char  text[32] = "elon";
};

I count 38 bytes. Gonna be tough to squeeze that into the 32 bytes allowed for payload.

UKHeliBob · January 30, 2020, 6:15pm

typedef struct package Package;
Package data;

What is this ?

You have a struct whose data type is package. To declare an instance of that struct you just need to do

package data;

As has been pointed out again the size of the struct is still too big

Danois90 · January 30, 2020, 6:24pm

You can only send 32 bytes of data in one message, but you can send larger amounts of data in multiple messages / chunks. You should ask yourself wheter you need to send any text at all? You could send a "text_id" identifying the text which is known to both ends..

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Problem with nRF24 data sending

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