I'm trying to connect a nRF24L01 with my Arduino Micro and Arduino Uno. The Arduino Uno works fine, but it doesn't talk with the Arduino Micro. CE is on pin 7 and CSN on pin 8. I posted the code down below into 2 Arduino IDE screens and changed one screen bool radioNumber = 1 and bool role = 1 and the other screen bool radioNumber = 0 and bool role = 0 so that they could communicate. However, the program with the Arduino Micro doesn't seem to work with pins 7 and 8. Is it code where something is wrong or do I need to change the pins and code? How do I make them both communicate with each other?

* 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"

/****************** 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() {
  Serial.println(F("*** PRESS 'T' to begin transmitting to the other node"));


  // 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.

  // Open a writing and reading pipe on each radio, with opposite addresses

  // Start the radio listening for data

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) )){

    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;

    if ( timeout ){                                             // Describe the results
        Serial.println(F("Failed, response timed out."));
        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(F(", Got response "));
        Serial.print(F(", Round-trip delay "));
        Serial.println(F(" microseconds"));

    // Try again 1s later

/****************** 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 "));

/****************** 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)

    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)


} // Loop
  • What's the output of .printdetails() function that exists in the library (you may need to include printf.h and also init printf)?
    – Avamander
    Nov 13, 2016 at 10:23
  • Use millis() and 200 or 200000L in wait for radio.available() block. Statement micros() - started_waiting_at > 200000 is not what you might think. Nov 13, 2016 at 10:47
  • 1
    The output for the transmitter says, " now sending" then after that says "failed, Failed response timed out". For the receiver it just says "sent response 23424332" and then it continues to say "sent reponse" but then with different numbers after that. When I use two arduino unos with same program it works fine. But when I add an arduino micro, it just keeps saying it failed. This what I'm trying to figure out, why it works on arduino uno and not micro Nov 13, 2016 at 17:46


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