Skip to main content
1 of 2

Printing Transmission data from NRF24L01+

I have a beginner's problem.... I have got 2 x NRF24L01+ devices, they are communicating with each other great, and i can talk with the nrf's via SPI. The problem is i want to display, on the serial monitor, the number of retransmitted packets (ARC_CNT) and the number of lost packets (PLOS_CNT), which are both in the "observe_tx" register on the nrf. I am using the "Getting Started" example from RF24 1.3.1, with Arduino 1.84, with a few more bits added, and it all works great apart from getting it to show PLOS_CNT & ARC_CNT! I have tried:

printf_P(PSTR("OBSERVE_TX=%02x: PLOS_CNT=%x ARC_CNT=%x\r\n"));

but this does not give the correct result. As you have probably guessed i know nothing about C or C++ :) There must be a simple way of showing the 2 numbers ?

The code i am using is :

    /*
    Getting Started example sketch for nRF24L01+ radios
    This is a very basic example of how to send data from one node to another
    Updated: Dec 2014 by TMRh20
    */

#include <SPI.h>
#include "RF24.h"
#include <printf.h> // Required for "radio.printDetails();"

/****************** User Config ***************************/
/***      Set this radio as radio number 0 or 1         ***/
bool radioNumber = 0;

/* Hardware configuration: Set up nRF24L01 radio on SPI bus plus pins 7 & 8 */
RF24 radio(7, 8);
/**********************************************************/

byte addresses[][6] = {"1Node", "2Node"};

// Used to control whether this node is sending or receiving
bool role = 0;

void setup() {
  //pinMode(53,OUTPUT);   //may not be required after all
  Serial.begin(115200);
  printf_begin();       //required for "radio.printDetails();" to work
  Serial.println(F("RF24/examples/GettingStarted"));
  Serial.println(F("*** PRESS 'T' to begin transmitting to the other node"));

  radio.begin();
  // Set the PA Level low to prevent power supply related issues since this is a
  // getting_started sketch, and the likelihood of close proximity of the devices. RF24_PA_MAX is default.
  radio.setPALevel(RF24_PA_LOW);    // _MIN, _LOW, _HIGH, _MAX
  radio.setDataRate(RF24_250KBPS);  //250KBPS, _1MBPS, _2MBPS  Lowest rate gives longest range.
  radio.setChannel(108);            // 0 - 124 (2.4GHz - 2.524GHz) Usually above 100 best. USA 70 - 80 best.
  //radio.enableDynamicPayloads();
  radio.setRetries(15, 15);         // set retry delay and no of retries. delay between retries, 0=250uS, 15 = 4000uS
  radio.setCRCLength(RF24_CRC_16);  // 8 or 16 bit crc
  //radio.setAutoAck(1);                    Ensure autoACK is enabled
  //radio.enableAckPayload();               Allow optional ack payloads
  //radio.setPayloadSize(1);                Here we are sending 1-byte payloads to test the call-response speed
  //radio.openWritingPipe(pipes[1]);        Both radios listen on the same pipes by default, and switch when writing
  //radio.openReadingPipe(1,pipes[0]);
  radio.printDetails(); //
  Serial.print(radio.getChannel());
  //Serial.print(radio.getxxxx());          prints to the serial port the value your are getting from the nRF24l01
  radio.setAutoAck(1);
  //radio.powerDown();
  //radio.powerUp();
  //radio.setAddressWidth(5);           // set AW to 3, 4 or 5.

  /*
     getChannel(); getPayloadSize(); getDynamicpayloadSize(); getPALevel(); getDataRate();  getCRCLength();
  */

  // Open a writing and reading pipe on each radio, with opposite addresses
  if (radioNumber) {
    radio.openWritingPipe(addresses[1]);
    radio.openReadingPipe(1, addresses[0]);
  } else {
    radio.openWritingPipe(addresses[0]);
    radio.openReadingPipe(1, addresses[1]);
  }

  // Start the radio listening for data
  radio.startListening();
}

void loop() {


  /****************** Ping Out Role ***************************/
  if (role == 1)  {

    radio.stopListening();                                    // First, stop listening so we can talk.


    Serial.println(F("Now sending"));

    unsigned long start_time = micros();                             // Take the time, and send it.  This will block until complete
    if (!radio.write( &start_time, sizeof(unsigned long) )) {
      Serial.println(F("failed"));
    }

    radio.startListening();                                    // Now, continue listening

    unsigned long started_waiting_at = micros();               // Set up a timeout period, get the current microseconds
    boolean timeout = false;                                   // Set up a variable to indicate if a response was received or not

    while ( ! radio.available() ) {                            // While nothing is received
      if (micros() - started_waiting_at > 200000 ) {           // If waited longer than 200ms, indicate timeout and exit while loop
        timeout = true;
        break;
      }
    }

    if ( timeout ) {                                            // Describe the results
      Serial.println(F("Failed, response timed out."));

      printf_P(PSTR("OBSERVE_TX=%02x: PLOS_CNT=%x ARC_CNT=%x\r\n"));

    } else {
      unsigned long got_time;                                 // Grab the response, compare, and send to debugging spew
      radio.read( &got_time, sizeof(unsigned long) );
      unsigned long end_time = micros();

      // Spew it
      Serial.print(F("Sent "));
      Serial.print(start_time);
      Serial.print(F(", Got response "));
      Serial.print(got_time);
      Serial.print(F(", Round-trip delay "));
      Serial.print(end_time - start_time);
      Serial.println(F(" microseconds"));
    }

    // Try again 1s later
    delay(1000);
  }



  /****************** Pong Back Role ***************************/

  if ( role == 0 )
  {
    unsigned long got_time;

    if ( radio.available()) {
      // Variable for the received timestamp
      while (radio.available()) {                                   // While there is data ready
        radio.read( &got_time, sizeof(unsigned long) );             // Get the payload
      }

      radio.stopListening();                                        // First, stop listening so we can talk
      radio.write( &got_time, sizeof(unsigned long) );              // Send the final one back.
      radio.startListening();                                       // Now, resume listening so we catch the next packets.
      Serial.print(F("Sent response "));
      Serial.println(got_time);
    }
  }




  /****************** Change Roles via Serial Commands ***************************/

  if ( Serial.available() )
  {
    char c = toupper(Serial.read());
    if ( c == 'T' && role == 0 ) {
      Serial.println(F("*** CHANGING TO TRANSMIT ROLE -- PRESS 'R' TO SWITCH BACK"));
      role = 1;                  // Become the primary transmitter (ping out)

    } else if ( c == 'R' && role == 1 ) {
      Serial.println(F("*** CHANGING TO RECEIVE ROLE -- PRESS 'T' TO SWITCH BACK"));
      role = 0;                // Become the primary receiver (pong back)
      radio.startListening();

    }
  }


        } // Loop