nRF24L01+

// nRF24L01+ on Arduino Uno: wiring and a free simulation at https://www.tinkered.ai/components/nrf24l01
// nRF24L01+ on an Arduino Uno: CE D9, CSN D10, SPI on D11/D12/D13
// Flash one board with isSender = true and another with isSender = false.
#include <SPI.h>
#include <RF24.h>

RF24 radio(9, 10); // CE, CSN
const uint8_t address[6] = "NODE1";
const bool isSender = true;
uint32_t counter = 0;

void setup() {
  Serial.begin(115200);
  if (!radio.begin()) {
    Serial.println("nRF24L01+ not responding: check wiring and the 3.3 V supply");
    while (true) {}
  }
  radio.setPALevel(RF24_PA_LOW); // low power for bench tests
  radio.setDataRate(RF24_1MBPS);
  radio.setChannel(76);
  radio.setPayloadSize(sizeof(counter));
  if (isSender) {
    radio.openWritingPipe(address);
    radio.stopListening();
  } else {
    radio.openReadingPipe(1, address);
    radio.startListening();
  }
  Serial.println(isSender ? "Sender ready" : "Receiver ready");
}

void loop() {
  if (isSender) {
    bool ok = radio.write(&counter, sizeof(counter));
    Serial.print("Sent ");
    Serial.print(counter);
    Serial.println(ok ? " (acknowledged)" : " (no acknowledgement)");
    counter++;
    delay(1000);
  } else if (radio.available()) {
    uint32_t value;
    radio.read(&value, sizeof(value));
    Serial.print("Received ");
    Serial.println(value);
  }
}

// nRF24L01+ on ESP32 DevKit V1: wiring and a free simulation at https://www.tinkered.ai/components/nrf24l01
// nRF24L01+ on an ESP32 DevKit V1: CE GPIO4, CSN GPIO5, VSPI on GPIO18/19/23
// Flash one board with isSender = true and another with isSender = false.
#include <SPI.h>
#include <RF24.h>

RF24 radio(4, 5); // CE, CSN
const uint8_t address[6] = "NODE1";
const bool isSender = true;
uint32_t counter = 0;

void setup() {
  Serial.begin(115200);
  if (!radio.begin()) {
    Serial.println("nRF24L01+ not responding: check wiring and the 3.3 V supply");
    while (true) { delay(100); }
  }
  radio.setPALevel(RF24_PA_LOW);
  radio.setDataRate(RF24_1MBPS);
  radio.setChannel(76);
  radio.setPayloadSize(sizeof(counter));
  if (isSender) {
    radio.openWritingPipe(address);
    radio.stopListening();
  } else {
    radio.openReadingPipe(1, address);
    radio.startListening();
  }
  Serial.println(isSender ? "Sender ready" : "Receiver ready");
}

void loop() {
  if (isSender) {
    bool ok = radio.write(&counter, sizeof(counter));
    Serial.printf("Sent %lu %s\n", (unsigned long)counter, ok ? "(acknowledged)" : "(no acknowledgement)");
    counter++;
    delay(1000);
  } else if (radio.available()) {
    uint32_t value;
    radio.read(&value, sizeof(value));
    Serial.printf("Received %lu\n", (unsigned long)value);
  }
}

// nRF24L01+ on Raspberry Pi Pico: wiring and a free simulation at https://www.tinkered.ai/components/nrf24l01
// nRF24L01+ on a Raspberry Pi Pico (arduino-pico): CE GP20, CSN GP17, SPI0 on GP16/18/19
// Flash one board with isSender = true and another with isSender = false.
#include <SPI.h>
#include <RF24.h>

RF24 radio(20, 17); // CE, CSN
const uint8_t address[6] = "NODE1";
const bool isSender = true;
uint32_t counter = 0;

void setup() {
  Serial.begin(115200);
  SPI.setRX(16);
  SPI.setSCK(18);
  SPI.setTX(19);
  if (!radio.begin()) {
    Serial.println("nRF24L01+ not responding: check wiring and the 3.3 V supply");
    while (true) { delay(100); }
  }
  radio.setPALevel(RF24_PA_LOW);
  radio.setDataRate(RF24_1MBPS);
  radio.setChannel(76);
  radio.setPayloadSize(sizeof(counter));
  if (isSender) {
    radio.openWritingPipe(address);
    radio.stopListening();
  } else {
    radio.openReadingPipe(1, address);
    radio.startListening();
  }
  Serial.println(isSender ? "Sender ready" : "Receiver ready");
}

void loop() {
  if (isSender) {
    bool ok = radio.write(&counter, sizeof(counter));
    Serial.print("Sent ");
    Serial.print(counter);
    Serial.println(ok ? " (acknowledged)" : " (no acknowledgement)");
    counter++;
    delay(1000);
  } else if (radio.available()) {
    uint32_t value;
    radio.read(&value, sizeof(value));
    Serial.print("Received ");
    Serial.println(value);
  }
}