Uno to Pro Micro with nRF24L01

I am using an Arduino Uno with an nRF24L01 module to communicate with an Arduino Pro Micro with an nRF24L01 module. The pin connections from the nRF24L01 module to the Arduino Uno are GND->GND, VCC->3.3V, CE->7, CSN->8, SCK->13, MOSI->11, and MISO->12. The pin connections from the nRF24L01 module to the Arduino Pro Micro are GND->GND, VCC->VCC, CE->7, CSN->8, SCK->15, MOSI->16, and MISO->14. Attached below is the GettingStarted code for the nRF24 library that I have. I am using version 1.8.19 of the Arduino IDE. The problem I am having is that I am unable to communication between the transmitter and receiver. I have fiddled around with about 5 or so other examples of basic communication such as a potentiometer on the Uno controlling a servo on the Micro, a button on the Uno controlling an LED on the Micro, and others. However, I have had to luck with getting the two to communicate. Are there any suggestions for what I should attempt next? If more information is needed, let me know.

https://nrf24.github.io/RF24/

/*
 * See documentation at https://nRF24.github.io/RF24
 * See License information at root directory of this library
 * Author: Brendan Doherty (2bndy5)
 */

/**
 * A simple example of sending data from 1 nRF24L01 transceiver to another.
 *
 * This example was written to be used on 2 devices acting as "nodes".
 * Use the Serial Monitor to change each node's behavior.
 */
#include <SPI.h>
#include "printf.h"
#include "RF24.h"

// instantiate an object for the nRF24L01 transceiver
RF24 radio(7, 8);  // using pin 7 for the CE pin, and pin 8 for the CSN pin

// Let these addresses be used for the pair
uint8_t address[][6] = { "1Node", "2Node" };
// It is very helpful to think of an address as a path instead of as
// an identifying device destination

// to use different addresses on a pair of radios, we need a variable to
// uniquely identify which address this radio will use to transmit
bool radioNumber = 1;  // 0 uses address[0] to transmit, 1 uses address[1] to transmit

// Used to control whether this node is sending or receiving
bool role = false;  // true = TX role, false = RX role

// For this example, we'll be using a payload containing
// a single float number that will be incremented
// on every successful transmission
float payload = 0.0;

void setup() {

  Serial.begin(115200);
  while (!Serial) {
    // some boards need to wait to ensure access to serial over USB
  }

  // initialize the transceiver on the SPI bus
  if (!radio.begin()) {
    Serial.println(F("radio hardware is not responding!!"));
    while (1) {}  // hold in infinite loop
  }

  // print example's introductory prompt
  Serial.println(F("RF24/examples/GettingStarted"));

  // To set the radioNumber via the Serial monitor on startup
  Serial.println(F("Which radio is this? Enter '0' or '1'. Defaults to '0'"));
  while (!Serial.available()) {
    // wait for user input
  }
  char input = Serial.parseInt();
  radioNumber = input == 1;
  Serial.print(F("radioNumber = "));
  Serial.println((int)radioNumber);

  // role variable is hardcoded to RX behavior, inform the user of this
  Serial.println(F("*** PRESS 'T' to begin transmitting to the other node"));

  // Set the PA Level low to try preventing power supply related problems
  // because these examples are likely run with nodes in close proximity to
  // each other.
  radio.setPALevel(RF24_PA_LOW);  // RF24_PA_MAX is default.

  // save on transmission time by setting the radio to only transmit the
  // number of bytes we need to transmit a float
  radio.setPayloadSize(sizeof(payload));  // float datatype occupies 4 bytes

  // set the TX address of the RX node into the TX pipe
  radio.openWritingPipe(address[radioNumber]);  // always uses pipe 0

  // set the RX address of the TX node into a RX pipe
  radio.openReadingPipe(1, address[!radioNumber]);  // using pipe 1

  // additional setup specific to the node's role
  if (role) {
    radio.stopListening();  // put radio in TX mode
  } else {
    radio.startListening();  // put radio in RX mode
  }

  // For debugging info
  // printf_begin();             // needed only once for printing details
  // radio.printDetails();       // (smaller) function that prints raw register values
  // radio.printPrettyDetails(); // (larger) function that prints human readable data

}  // setup

void loop() {

  if (role) {
    // This device is a TX node

    unsigned long start_timer = micros();                // start the timer
    bool report = radio.write(&payload, sizeof(float));  // transmit & save the report
    unsigned long end_timer = micros();                  // end the timer

    if (report) {
      Serial.print(F("Transmission successful! "));  // payload was delivered
      Serial.print(F("Time to transmit = "));
      Serial.print(end_timer - start_timer);  // print the timer result
      Serial.print(F(" us. Sent: "));
      Serial.println(payload);  // print payload sent
      payload += 0.01;          // increment float payload
    } else {
      Serial.println(F("Transmission failed or timed out"));  // payload was not delivered
    }

    // to make this example readable in the serial monitor
    delay(1000);  // slow transmissions down by 1 second

  } else {
    // This device is a RX node

    uint8_t pipe;
    if (radio.available(&pipe)) {              // is there a payload? get the pipe number that recieved it
      uint8_t bytes = radio.getPayloadSize();  // get the size of the payload
      radio.read(&payload, bytes);             // fetch payload from FIFO
      Serial.print(F("Received "));
      Serial.print(bytes);  // print the size of the payload
      Serial.print(F(" bytes on pipe "));
      Serial.print(pipe);  // print the pipe number
      Serial.print(F(": "));
      Serial.println(payload);  // print the payload's value
    }
  }  // role

  if (Serial.available()) {
    // change the role via the serial monitor

    char c = toupper(Serial.read());
    if (c == 'T' && !role) {
      // Become the TX node

      role = true;
      Serial.println(F("*** CHANGING TO TRANSMIT ROLE -- PRESS 'R' TO SWITCH BACK"));
      radio.stopListening();

    } else if (c == 'R' && role) {
      // Become the RX node

      role = false;
      Serial.println(F("*** CHANGING TO RECEIVE ROLE -- PRESS 'T' TO SWITCH BACK"));
      radio.startListening();
    }
  }

}  // loop

I would suggest you start here:

Start with post #1 to get the wiring right. Then jump to post #30 and run the CheckConnection.ino sketch to check for successful communications between your micro and the radio module. Post the output of the sketch here if you are unsure. Then go back to post #2 and run the simple Tx & Rx sketches.

The code has been proven to work for 100's of users.

You should also make sure that your 3.3V supply is up to the job. The 3.3V output on the UNO and Pro Micro will struggle. Try a couple of AA batteries as your power source for the modules instead.

Definetly run the connection test first, not point in trying anything else if that does not work. This specific test does not use transmit mode so is not that demanding on power supplies.

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