I've been using NRF24L01+ modules for nearly 2 years without any issues, and have consistently achieved a range >100ft in the past. Recently, when I uploaded some new code to the modules, I found they had a range of <50ft (with no obstructions), which is insufficient for my needs. I figured my code was bad, so I tried two getting started/hello world codes from tutorials which I have attached and linked below. Each program gave similarly poor ranges, even though I have achieved >50ft (probably >100ft) range with them in the past. I am using v1.1.7 of the TMRh20 version of the RF24 library, as instructed in the Robin2 tutorial linked below. Because the "known good" software that had worked in the past didn't fix the issue, I assumed I must have had a hardware issue.
For these tests, I was using Elegoo Unos (info below) as the transmitter and receiver. I wired everything according to the directions on the tutorials. 10uf capacitors were used for the 3.3v input to the module. I tried two different radio modules (links below) and still had the same issue. I substituted in an Elegoo Nano (again wired according to the tutorials) and saw no change.
At this point, I figured I had tried all the obvious issues, so I got creative and tested the following:
different versions of the ide: (1.8.13 and 1.8.15)
different computers, usb ports, and usb cables
a different testing location (miles away) in case there was some weird interference
different channels
different PA levels
different driver versions
different module orientation
powering the transmitter from a power brick instead of a computer
different wires between Arduinos and radios
Unfortunately, none of these fixed my low range issue, and I have no idea what to try next. If anyone has any suggestions for how to fix/troubleshoot this issue, I would be greatly appreciative. This is my first time using the forum, so sorry in advance for any formatting errors.
Robin2 code
SimpleTx.ino:
// 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.begin(9600);
Serial.println("SimpleTx Starting");
radio.begin();
radio.setDataRate( RF24_250KBPS );
radio.setRetries(3,5); // delay, count
radio.openWritingPipe(slaveAddress);
}
//====================
void loop() {
currentMillis = millis();
if (currentMillis - prevMillis >= txIntervalMillis) {
send();
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 ");
Serial.print(dataToSend);
if (rslt) {
Serial.println(" Acknowledge received");
updateMessage();
}
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;
}
SimpleRx.ino:
// SimpleRx - the slave or the receiver
#include <SPI.h>
#include <nRF24L01.h>
#include <RF24.h>
#define CE_PIN 9
#define CSN_PIN 10
const byte thisSlaveAddress[5] = {'R','x','A','A','A'};
RF24 radio(CE_PIN, CSN_PIN);
char dataReceived[10]; // this must match dataToSend in the TX
bool newData = false;
//===========
void setup() {
Serial.begin(9600);
Serial.println("SimpleRx Starting");
radio.begin();
radio.setDataRate( RF24_250KBPS );
radio.openReadingPipe(1, thisSlaveAddress);
radio.startListening();
}
//=============
void loop() {
getData();
showData();
}
//==============
void getData() {
if ( radio.available() ) {
radio.read( &dataReceived, sizeof(dataReceived) );
newData = true;
}
}
void showData() {
if (newData == true) {
Serial.print("Data received ");
Serial.println(dataReceived);
newData = false;
}
}
How To Mechatronics code
Transmitter code:
/*
* Arduino Wireless Communication Tutorial
* Example 1 - Transmitter Code
*
* by Dejan Nedelkovski, www.HowToMechatronics.com
*
* Library: TMRh20/RF24, https://github.com/tmrh20/RF24/
*/
#include <SPI.h>
#include <nRF24L01.h>
#include <RF24.h>
RF24 radio(7, 8); // CE, CSN
const byte address[6] = "00001";
void setup() {
radio.begin();
radio.openWritingPipe(address);
radio.setPALevel(RF24_PA_MIN);
radio.stopListening();
}
void loop() {
const char text[] = "Hello World";
radio.write(&text, sizeof(text));
delay(1000);
}
Receiver Code:
/*
* Arduino Wireless Communication Tutorial
* Example 1 - Receiver Code
*
* by Dejan Nedelkovski, www.HowToMechatronics.com
*
* Library: TMRh20/RF24, https://github.com/tmrh20/RF24/
*/
#include <SPI.h>
#include <nRF24L01.h>
#include <RF24.h>
RF24 radio(7, 8); // CE, CSN
const byte address[6] = "00001";
void setup() {
Serial.begin(9600);
radio.begin();
radio.openReadingPipe(0, address);
radio.setPALevel(RF24_PA_MIN);
radio.startListening();
}
void loop() {
if (radio.available()) {
char text[32] = "";
radio.read(&text, sizeof(text));
Serial.println(text);
}
}