HW237

The HW237 uses the Nordic nRF24L01+ transceiver and provides powerful GFSK-modulated data transmission on the 2.4GHz license-free ISM band.

This board features an integrated programmable PA (RF amplifier) that can boost the chips’ 1mW RF output power to 100mW. It also comes with an LNA circuit for better reception.

Based on data rate, the board can reach long distances of up to 1100m (at 250kbps). At the fastest data rate of 2MBps, the operating range is still around 500m (all in open terrain/line of sight).

The drop-in compatible nRF24L01+ provides much improved intermodulation and wideband blocking compared to the nRF24L01 plus additional internal RF filters to meet regulatory standards (i.e. stray emissions).

Board Variations

The board is available in three variations:

• On-Board Antenna: Antenna is printed on the board (compact), no PA, 1mW RF power, low transmission range of <100m
• SMA Connector: Connector for external antenna, transmission range <500m
• SMA + PA + LNA: Additional power amplifier and low-noise amplifier (LNA), up to 100mW RF power, transmission range of up to 1.100m

All boards have the same pin-out and are RF-compatible.

You can tell the difference by looking at the SMA antenna connector and the number of micro chips on the board:

• when the connector is pointing upwards and there is just one micro chip on the board, then it is the version without power amplifier.
• when the connector is pointing horizontally and there are two chips present, then it is the version with the power amplifier.

The picture below shows both chips: the one marked NRF24L01+ is the transceiver, and the one marked AT2401C is the PA/LNA.

Technical Data

Connectors

The board comes with 2x4 connector pins that are clearly labeled on the backside.

Interface

This board uses the SPI interface to communicate with a microcontroller.

Connections

Here is an example of a setup with an Arduino Nano and Arduino Mega:

Library

There are many libraries available on github to operate the nRFL01 transceiver. RF24 is one of them.

Here is a very simple transmitter code (make sure you adjust the pin numbers so they fit the SPI pins on your microcontroller):

/*
* 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);
}

And this would be the simplistic 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);
  }
}

The full explanation of the code can be found here.

Data Sheet

nRF24L01
nRF24L01+
AT2401C PA/LNA (Chinese)

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^{_{(content created Apr 17, 2024)}}