Wireless SI4432 Up to 1000m Module

Features

• Uses Silicon Labs Si4432 transceiver for stable and reliable performance.
• Frequency: 433.92 MHz.
• Maximum output power: +20 dBm for long-range RF communication.
• Data rates: 0.123–256 kbps.
• Supports FSK, GFSK, and OOK modulation.
• Operating voltage: 1.8–3.6V.
• Low-power shutdown mode.
• Digital RSSI for signal strength monitoring.
• Timing wake-up function for energy saving.
• Automatic antenna matching and two-way switch control.

Pinout

Applications

• Remote control systems (garage doors, keyless entry)
• Remote meter reading (electricity, water, gas)
• Home security and automation
• Industrial control and monitoring systems
• Telemetry and sensor networks
• Health monitoring and personal data recording
• Wireless PC peripherals (keyboard, mouse)
• Tire pressure monitoring
• RFID tag readers and asset tracking

Circuit Connection

Let's create a project for sending humidity and temperature sensor data from an Arduino board on request to another Arduino board via a radio channel.

We will need the following components:

Note: Operates at 3.3V; use a level shifter or voltage divider if connecting to 5V logic.

Library

1. To program the module, we use the RF22 library. We load the rf22_client library example onto one board, and the rf22_server library example onto the other.
2. Open Arduino IDE → Sketch → Include Library → Manage Libraries
3. Search for "RF22 " and install it

Code:

The client sends a tempSH21 (or humiditySH21) message over the radio every 3 seconds and waits for a response. Upon receiving a response, it displays the data on the serial monitor. The sketch contents are shown in Listing 1.

Listing 1

#include "SPI.h"
#include "RF22.h"
// create RF object
RF22 si4432client;
// to select humidity/temperature
int choice=0;
void setup()
{
Serial.begin(9600);
if (!si4432client.init())
 Serial.println("si4432 no init");
}
void loop()
{
 Serial.println("Send request");
 // send a request to the server
 if(choice==0) {
 uint8_t senddata[] = "tempSH21";
 si4432client.send(senddata, sizeof(senddata));
 }
 else {
 uint8_t senddata[] = "humiditySH21";
 si4432client.send(senddata, sizeof(senddata));
 }
 si4432client.waitPacketSent();
 // waiting for response
 uint8_t getdata [RF22_MAX_MESSAGE_LEN];
 uint8_t length1 = sizeof(getdata);
 if (si4432client.waitAvailableTimeout(1000))
 {
 // received message
 if (si4432client.recv(getdata, &length1))
 {
 Serial.print("got reply: ");
 if(choice==0)
 Serial.print(" tempSH21=");
 else
 Serial.print("humiditySH21=");
 Serial.println((char*) getdata);
 }
 }
 choice=1-choice;
 delay(3000);
}

The server, upon receiving a tempSH21 (or humiditySH21) request, retrieves the required data from the SHT21 sensor and responds with the value of the requested parameter. The sketch contents are shown in Listing 2.

Listing 2

#include "SPI.h"
#include "RF22.h"
#include "Wire.h"
#include "SHT2x.h"
// create RF object
RF22 si4432server;
void setup()
{
Wire.begin();
Serial.begin(9600);
if (!si4432server.init())
 Serial.println("si4432 init no");
}
void loop()
{
 si4432server.waitAvailable();
 // received message
 uint8_t getdata [RF22_MAX_MESSAGE_LEN];
 uint8_t length1 = sizeof(getdata);
 if (si4432server.recv(getdata, &length1))
 {
 Serial.print("get request: ");
 Serial.println((char*) getdata);
 char senddata[] = " ";
 if(StrContains((char*) getdata,"tempSH21")!=0)
 {
 dtostrf(SHT2x.GetTemperature(),10,2,senddata);
 }
 else if(StrContains((char*)buf,"humiditySH21")!=0)
 {
 dtostrf(SHT2x.GetHumidity(),10,2,sendata);
 }
 else
 {
 Serial.println("error");
 dtostrf(999,10,0,data);
 }
 si4432server.send((uint8_t*)datasend, sizeof(datasend));
 si4432server.waitPacketSent();
 Serial.println("Sent a reply");
 }
}

Technical Details

• Frequency Range: 433.92 MHz
• Maximum Output Power: +20 dBm
• Data Transfer Rate: 0.123–256 kbps
• Modulation: FSK, GFSK, OOK
• Power Supply: 1.8–3.6V
• Sensitivity: up to -121 dBm
• Low-power shutdown mode
• Digital RSSI and timing wake-up
• Automatic antenna matching, two-way switch control

Resources:

Tutorial

Comparison

Compared to nRF24 modules, the SI4432 supports lower data rates but longer range, wider frequency coverage (240–960 MHz), and higher output power. It is ideal for applications needing long-range communication, configurable settings, and stable RF performance.