This post is a guide for the popular RF 433MHz Transmitter/Receiver modules with Arduino. We’ll explain how they work and share an Arduino project example that you can apply to use in your own projects.
We have other tutorials about the 433MHz transmitter/receiver that you may found useful:
Throughout this tutorial we’ll be using the FS1000A transmitter and corresponding receiver, but the instructions provided also work with other 433MHz transmitter/receiver modules that work in a similar fashion. These RF modules are very popular among the Arduino tinkerers and are used on a wide variety of applications that require wireless control.
These modules are very cheap and you can use them with any microcontroller, whether it’s an Arduino, ESP8266, or ESP32.
Specifications RF 433MHz Receiver
Specifications RF 433MHz Transmitter
You can purchase these modules for just a few dollars. Click here to compare the RF 433MHz transmitter/receiver on several stores and find the best price.
In this section, we’ll build a simple example that sends a message from an Arduino to another Arduino board using 433 MHz. An Arduino board will be connected to a 433 MHz transmitter and will send the “Hello World!” message. The other Arduino board will be connected to a 433 MHz receiver to receive the messages.
You need the following components for this example:
You can use the preceding links or go directly to MakerAdvisor.com/tools to find all the parts for your projects at the best price!
The RadioHead library provides an easy way to work with the 433 MHz transmitter/receiver with the Arduino. Follow the next steps to install that library in the Arduino IDE:
The RadioHead library is great and it works with almost all RF modules in the market. You can read more about the RadioHead library here.
Wire the transmitter module to the Arduino by following the next schematic diagram.
Important: always check the pinout for the transmitter module you’re using. Usually, there are labels next to the pins. Alternatively, you can also take a look at your module’s datasheet.
Upload the following code to the Arduino board that will act as a transmitter. This is based on one of the examples provided by the RadioHead library.
#include <RH_ASK.h> #include <SPI.h> // Not actually used but needed to compile RH_ASK driver; void setup() { Serial.begin(9600); // Debugging only if (!driver.init()) Serial.println("init failed"); } void loop() { const char *msg = "Hello World!"; driver.send((uint8_t *)msg, strlen(msg)); driver.waitPacketSent(); delay(1000); }
First, include the RadioHead ASK library.
#include <RH_ASK.h>This library needs the SPI library to work. So, you also need to include the SPI library.
#include <SPI.h>After that, create a RH_ASK object called driver.
In the setup(), initialize the RH_ASK object by using the init() method.
Serial.begin(9600); // Debugging only if (!driver.init()) Serial.println("init failed");
In the loop(), we write and send our message. The message is saved on the msg variable. Please note that the message needs to be of type char.
const char *msg = "Hello World!";
This message contains the “Hello World!” message, but you can send anything you want as long as it is in char format.
Finally, we send our message as follows:
driver.send((uint8_t *)msg, strlen(msg)); driver.waitPacketSent();
The message is being sent every second, but you can adjust this delay time.
delay(1000);
Wire the receiver module to another Arduino by following the next schematic diagram.
Important: always check the pinout for the transmitter module you’re using. Usually, there are labels next to the pins. Alternatively, you can also take a look at your module’s datasheet.
Upload the code below to the Arduino connected to the receiver. This is based on one of the examples provided by the RadioHead library.
#include <RH_ASK.h> #include <SPI.h> // Not actualy used but needed to compile RH_ASK driver; void setup() { Serial.begin(9600); // Debugging only if (!driver.init()) Serial.println("init failed"); } void loop() { uint8_t buf[12]; uint8_t buflen = sizeof(buf); if (driver.recv(buf, &buflen)) // Non-blocking { int i; // Message with a good checksum received, dump it. Serial.print("Message: "); Serial.println((char*)buf); } }
Similarly to the previous sketch, you start by including the necessary libraries:
#include <RH_ASK.h> #include <SPI.h>
You create a RH_ASK object called driver:
RH_ASK driver;In the setup(), initialize the RH_ASKobject.
void setup(){ Serial.begin(9600); // Debugging only if (!driver.init()) Serial.println("init failed"); }
In the loop(), we need to set a buffer that matches the size of the message we’ll receive. “Hello World!” has 12 characters. You should adjust the buffer size accordingly to the message you’ll receive (spaces and punctuation also count).
uint8_t buf[12]; uint8_t buflen = sizeof(buf);
Then, check if you’ve received a valid message. If you receive a valid message, print it in the serial monitor.
if (driver.recv(buf, &buflen)) { int i; // Message with a good checksum received, dump it. Serial.print("Message: "); Serial.println((char*)buf); }
In this project the transmitter is sending a message “Hello World!” to the receiver via RF. Those messages are being displayed in receiver’s serial monitor. The following figure shows what you should see in your Arduino IDE serial monitor.
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