I have followed numerous guides and tutorials for getting the NRF24L01+ modules working with an Arduino Uno. I have swapped to a genuine Arduino and tried 4 different NRF modules. All without luck.

I am trying to get the most basic example from Simple nRF24L01+ 2.4GHz transceiver demo to work.

Hardware Connections: Hardware Connections

Simple TX Test Code:

// SimpleTx - the master or the transmitter

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

#define CE_PIN   9
#define CSN_PIN 10

const byte slaveAddress[5] = {'R','x','A','A','A'};

RF24 radio(CE_PIN, CSN_PIN); // Create a Radio

char dataToSend[10] = "Message 0";
char txNum = '0';

unsigned long currentMillis;
unsigned long prevMillis;
unsigned long txIntervalMillis = 1000; // send once per second

void setup() {


    Serial.println("SimpleTx Starting");

    radio.setDataRate( RF24_250KBPS );
    radio.setRetries(3,5); // delay, count


void loop() {
    currentMillis = millis();
    if (currentMillis - prevMillis >= txIntervalMillis) {
        prevMillis = millis();


void send() {

    bool rslt;
    rslt = radio.write( &dataToSend, sizeof(dataToSend) );
        // Always use sizeof() as it gives the size as the number of bytes.
        // For example if dataToSend was an int sizeof() would correctly return 2

    Serial.print("Data Sent ");

    if (rslt) {
        Serial.println("  Acknowledge received");
    else {
        Serial.println("  Tx failed");


void updateMessage() {
        // so you can see that new data is being sent
    txNum += 1;
    if (txNum > '9') {
        txNum = '0';
    dataToSend[8] = txNum;

Serial monitor:

enter image description here

Using radio.printDetails( ); returns:

enter image description here

Please let me know what I'm missing.

  • Can you please upload the unmodified PingPair example and see if that works?
    – Avamander
    Commented May 10, 2019 at 13:25
  • Where is the code for the receiving side? If there is no receiver, the sender won't get an ACK packet back, and you get the TX failed error message.
    – Gerben
    Commented May 10, 2019 at 13:32
  • What is this: uint8_t slaveAddress[5] = {0xF0F0F0F0A1LL, 0XF0F0F0F0B1LL, 0XF0F0F0F0C1LL, 0XF0F0F0F0D1LL, 0XF0F0F0F0E1LL};? How do you expect such large values to fit into uint8_t??? The compiler will interpret this as uint8_t slaveAddress[5] = {0xA1, 0xB1, 0xC1, 0xD1, 0xE1};. Is this what you wanted? I'd guess not. Also, take a look here github.com/nRF24/RF24/blob/master/RF24.h#L246 how the address is supposed to be formed. Commented May 10, 2019 at 14:58
  • @AnT I was trying the same as 1 of the answers here: arduino.stackexchange.com/questions/65249/… before you commented there as well. Thank you, have updated the question and code.
    – Jak
    Commented May 12, 2019 at 14:57
  • Thank you all so much. Not sure why I was expecting the radio.write function to return True without a receiving end. It's working.
    – Jak
    Commented May 12, 2019 at 15:13

1 Answer 1


The Arduinos 3V3 does not privide enough current. To eliminate this as a source of your problem you can use a ceramic capacitor of 100µF across VCC and GND pins of the nRF24L01+ module or buy a 5V to 3V3 step down converter specially made for nRF24L01.

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