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Project Help and Ideas » Wireless RF Transceiver 431-470MHz GFSK Data Transfer

May 22, 2011
by kle8309
kle8309's Avatar

I bought a couple of these modules recently from for $30 (I almost bought the xbee but decided to save money)

rf modules

I got them to work and I'm gonna explain how to use them.

The nice features that these modules have are: uart ready, and easy set up (only 7 pins)

The pins are GND, 3.3V/5V, Enable, RXD, TXD, B/RX, A/TX

Ground the B/RX and A/TX if you want to use uart

The enable is active high

The module has a nice data buffer 512 bytes

basically if you want to send say char you would send it using uart_send from

the MCU (you need to connect the MCU's RXD and TXD to the corresponding module

pins)the module will load it up and send immediately. This is like shoot and


Or you can do what I did, using a hyperterminal (so you don't have to use the

MCUs for testing)

either putty or something else nicer (but you need to compile it code using visual studio like I did)

microsoft c++ code

Note RF baudrate is 9600 on default

RFID is also default (unless you can use rf-magic software)

Here is a demo of the setup and test RF demo

I'm still working on the rf-magic. I need to get the rs-232 cable first.

But unless you plan on buying more than a set of two, you have to care about

changing the default settings.

I'm planning on using this to control a robot from my own room!

Did I mention it can transmit up to 1000 meters! Well on paper anyways.


May 24, 2011
by kle8309
kle8309's Avatar

Alright, so decided to pimp out my uart interface a bit and work on some of my programming skills.

This is the c++ code for form.h that I used for my Windows Forms Application (New CRL project and Windows Forms App).

I learn a lot by doing this. Just a hint of how to access the different components of the windows forms: use this->name of oject->property.

It took me a while to learn how to use the "this" function.

Last thing I want to say is use the Microsoft support page for example, it's great help!

I will post a video demonstrating this later on.

My next objective will be to use threads in the program (backgroundworker as they call it).

Lastly, I will try to communicate with a social network page like facebook to update information

(nice feature if you're building a robot)

#pragma once

namespace test3 {

    using namespace System;
    using namespace System::ComponentModel;
    using namespace System::Collections;
    using namespace System::Windows::Forms;
    using namespace System::Data;
    using namespace System::Drawing;
    using namespace System::IO::Ports;

    /// <summary>
    /// Summary for Form1
    /// </summary>
    public ref class Form1 : public System::Windows::Forms::Form


            //TODO: Add the constructor code here

        /// <summary>
        /// Clean up any resources being used.
        /// </summary>
            if (components)
                delete components;
    private: System::IO::Ports::SerialPort^  _serialPort;
    private: System::Windows::Forms::Button^  button1;
    private: System::Windows::Forms::TextBox^  textBox1;
    private: System::Windows::Forms::ComboBox^  comboBox1;
    private: System::Windows::Forms::Button^  button2;
    private: System::Windows::Forms::ComboBox^  comboBox2;
    private: System::Windows::Forms::Button^  button3;

    private: System::Windows::Forms::TextBox^  textBox2;
    private: System::Windows::Forms::ProgressBar^  progressBar1;
    private: System::Windows::Forms::Button^  button4;
    private: System::Windows::Forms::Label^  label1;

    private: System::ComponentModel::IContainer^  components;

        /// <summary>
        /// Required designer variable.
        /// </summary>

#pragma region Windows Form Designer generated code
        /// <summary>
        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.
        /// </summary>
        void InitializeComponent(void)
            this->components = (gcnew System::ComponentModel::Container());
            this->_serialPort = (gcnew System::IO::Ports::SerialPort(this->components));
            this->button1 = (gcnew System::Windows::Forms::Button());
            this->textBox1 = (gcnew System::Windows::Forms::TextBox());
            this->comboBox1 = (gcnew System::Windows::Forms::ComboBox());
            this->button2 = (gcnew System::Windows::Forms::Button());
            this->comboBox2 = (gcnew System::Windows::Forms::ComboBox());
            this->button3 = (gcnew System::Windows::Forms::Button());
            this->textBox2 = (gcnew System::Windows::Forms::TextBox());
            this->progressBar1 = (gcnew System::Windows::Forms::ProgressBar());
            this->button4 = (gcnew System::Windows::Forms::Button());
            this->label1 = (gcnew System::Windows::Forms::Label());
            // _serialPort
            this->_serialPort->PortName = L"COM5";
            this->_serialPort->ReadTimeout = 500;
            this->_serialPort->WriteTimeout = 500;
            // button1
            this->button1->Font = (gcnew System::Drawing::Font(L"Microsoft Sans Serif", 12, System::Drawing::FontStyle::Bold, System::Drawing::GraphicsUnit::Point, 
            this->button1->Location = System::Drawing::Point(36, 125);
            this->button1->Name = L"button1";
            this->button1->Size = System::Drawing::Size(101, 62);
            this->button1->TabIndex = 0;
            this->button1->Text = L"Send";
            this->button1->UseVisualStyleBackColor = true;
            this->button1->Click += gcnew System::EventHandler(this, &Form1::button1_Click);
            // textBox1
            this->textBox1->BackColor = System::Drawing::Color::FromArgb(static_cast<System::Int32>(static_cast<System::Byte>(255)), static_cast<System::Int32>(static_cast<System::Byte>(192)), 
            this->textBox1->Font = (gcnew System::Drawing::Font(L"Microsoft Sans Serif", 12, System::Drawing::FontStyle::Regular, System::Drawing::GraphicsUnit::Point, 
            this->textBox1->ForeColor = System::Drawing::SystemColors::Desktop;
            this->textBox1->Location = System::Drawing::Point(36, 203);
            this->textBox1->Name = L"textBox1";
            this->textBox1->Size = System::Drawing::Size(261, 26);
            this->textBox1->TabIndex = 1;
            this->textBox1->Text = L"Enter Here";
            // comboBox1
            this->comboBox1->AllowDrop = true;
            this->comboBox1->Font = (gcnew System::Drawing::Font(L"Microsoft Sans Serif", 12, System::Drawing::FontStyle::Regular, System::Drawing::GraphicsUnit::Point, 
            this->comboBox1->FormattingEnabled = true;
            this->comboBox1->Location = System::Drawing::Point(395, 12);
            this->comboBox1->Name = L"comboBox1";
            this->comboBox1->Size = System::Drawing::Size(102, 28);
            this->comboBox1->TabIndex = 2;
            this->comboBox1->Text = L"COM ports";
            // button2
            this->button2->Font = (gcnew System::Drawing::Font(L"Microsoft Sans Serif", 12, System::Drawing::FontStyle::Bold, System::Drawing::GraphicsUnit::Point, 
            this->button2->Location = System::Drawing::Point(395, 98);
            this->button2->Name = L"button2";
            this->button2->Size = System::Drawing::Size(101, 62);
            this->button2->TabIndex = 3;
            this->button2->Text = L"Init Port";
            this->button2->UseVisualStyleBackColor = true;
            this->button2->Click += gcnew System::EventHandler(this, &Form1::button2_Click);
            // comboBox2
            this->comboBox2->AllowDrop = true;
            this->comboBox2->Font = (gcnew System::Drawing::Font(L"Microsoft Sans Serif", 12, System::Drawing::FontStyle::Regular, System::Drawing::GraphicsUnit::Point, 
            this->comboBox2->FormattingEnabled = true;
            this->comboBox2->Items->AddRange(gcnew cli::array< System::Object^  >(3) {L"9600", L"38400", L"115200"});
            this->comboBox2->Location = System::Drawing::Point(395, 64);
            this->comboBox2->Name = L"comboBox2";
            this->comboBox2->Size = System::Drawing::Size(102, 28);
            this->comboBox2->TabIndex = 4;
            this->comboBox2->Text = L"Baud rate";
            // button3
            this->button3->Font = (gcnew System::Drawing::Font(L"Microsoft Sans Serif", 12, System::Drawing::FontStyle::Bold, System::Drawing::GraphicsUnit::Point, 
            this->button3->Location = System::Drawing::Point(195, 125);
            this->button3->Name = L"button3";
            this->button3->Size = System::Drawing::Size(101, 62);
            this->button3->TabIndex = 5;
            this->button3->Text = L"Read";
            this->button3->UseVisualStyleBackColor = true;
            this->button3->Click += gcnew System::EventHandler(this, &Form1::button3_Click);
            // textBox2
            this->textBox2->BackColor = System::Drawing::Color::FromArgb(static_cast<System::Int32>(static_cast<System::Byte>(255)), static_cast<System::Int32>(static_cast<System::Byte>(192)), 
            this->textBox2->Font = (gcnew System::Drawing::Font(L"Microsoft Sans Serif", 12, System::Drawing::FontStyle::Regular, System::Drawing::GraphicsUnit::Point, 
            this->textBox2->Location = System::Drawing::Point(36, 82);
            this->textBox2->Name = L"textBox2";
            this->textBox2->Size = System::Drawing::Size(260, 26);
            this->textBox2->TabIndex = 7;
            this->textBox2->Text = L"Received Here";
            // progressBar1
            this->progressBar1->Location = System::Drawing::Point(37, 32);
            this->progressBar1->Name = L"progressBar1";
            this->progressBar1->Size = System::Drawing::Size(100, 32);
            this->progressBar1->TabIndex = 9;
            this->progressBar1->Click += gcnew System::EventHandler(this, &Form1::progressBar1_Click);
            // button4
            this->button4->Font = (gcnew System::Drawing::Font(L"Microsoft Sans Serif", 12, System::Drawing::FontStyle::Bold, System::Drawing::GraphicsUnit::Point, 
            this->button4->Location = System::Drawing::Point(395, 167);
            this->button4->Name = L"button4";
            this->button4->Size = System::Drawing::Size(101, 62);
            this->button4->TabIndex = 10;
            this->button4->Text = L"Close Port";
            this->button4->UseVisualStyleBackColor = true;
            this->button4->Click += gcnew System::EventHandler(this, &Form1::button4_Click);
            // label1
            this->label1->AutoSize = true;
            this->label1->Font = (gcnew System::Drawing::Font(L"Microsoft Sans Serif", 12, System::Drawing::FontStyle::Bold, System::Drawing::GraphicsUnit::Point, 
            this->label1->Location = System::Drawing::Point(32, 9);
            this->label1->Name = L"label1";
            this->label1->Size = System::Drawing::Size(100, 20);
            this->label1->TabIndex = 11;
            this->label1->Text = L"Port Status";
            // Form1
            this->AutoScaleDimensions = System::Drawing::SizeF(6, 13);
            this->AutoScaleMode = System::Windows::Forms::AutoScaleMode::Font;
            this->BackColor = System::Drawing::Color::Silver;
            this->ClientSize = System::Drawing::Size(545, 262);
            this->Name = L"Form1";
            this->Text = L"Uart Gui v1.1";


#pragma endregion

    private: void findPorts(void)
            // get port names
            array<Object^>^ objectArray = SerialPort::GetPortNames();
            // add string array to combobox
            this->comboBox1->Items->AddRange( objectArray );

    // Send button
    private: System::Void button1_Click(System::Object^  sender, System::EventArgs^  e) {
                 // add sender name
                 String^ name = this->_serialPort->PortName;
                 // grab text and store in send buffer
                 String^ message = this->textBox1->Text;
                 // write to serial
                    this->_serialPort->WriteLine(String::Format("<{0}>: {1}",name,message));
                    this->textBox1->Text="Port Not Opened";
    // Init button
    private: System::Void button2_Click(System::Object^  sender, System::EventArgs^  e) {
                 // set COM port
                 StringComparer^ stringComparer = StringComparer::OrdinalIgnoreCase;
                 if(stringComparer->Equals("COM ports",this->comboBox1->Text)){
                    this->textBox1->Text="Please Select COM Port";
                 else if(stringComparer->Equals("Baud rate",this->comboBox2->Text)){
                    this->textBox1->Text="Please Select Baud Rate";

                    this->textBox1->Text="Enter Message Here";
                 //open serial port 
                 // is open status


        // Read button
    private: System::Void button3_Click(System::Object^  sender, System::EventArgs^  e) {

                 // discard input buffer
                 // this->_serialPort->DiscardInBuffer();
                    try {
                    catch (TimeoutException ^) {
                        this->textBox2->Text="TimeoutException: No Input";

                     this->textBox2->Text="Port Not Opened";


    private: System::Void progressBar1_Click(System::Object^  sender, System::EventArgs^  e) {

    // close port button
    private: System::Void button4_Click(System::Object^  sender, System::EventArgs^  e) {
                //close serialPort

May 25, 2011
by kle8309
kle8309's Avatar

gui demo

August 14, 2011
by kle8309
kle8309's Avatar

an update on my current project

wireless controller with VS C#

August 14, 2011
by Ralphxyz
Ralphxyz's Avatar

kle8309, would you post a outline or summary of your project, the different components etc.

Is the GUI C++ or C#?

Nice project,


August 14, 2011
by kle8309
kle8309's Avatar


Sorry for the confusion

I first started the project with c++, and now I'm switching to C# (almost the same

thing). I will post a

project summary soon.

December 20, 2011
by bluestang
bluestang's Avatar

This is insane loved watching the tutorials and I am impressed by what is happening here.. could you let us know what atmel chips you were using and that if you stayed with c#?

December 20, 2011
by kle8309
kle8309's Avatar

@ bluestang

Thank you for your interest.

I used the typical Atmega328P chip to interface with the RF transceiver and yes I love C# now that I switched. C# just makes more sense on so many levels. In fact, C# is so cool that I even bought a FEZ panda II which is C# based. Working on this project will help you home your skills for C/C++/C#. If you seen the twitterizer project you will know what I mean.

Here is the link to the serial COM port code. You can actually try it out by using the installation file.

sourceforge link

Please let me know if you have any questions on how to get started. VS is so awesome and it's free for students on the site

Maybe I should post a complete set of videos tutorial on this project since more and more people started to ask questions. Let me know what you think.


December 21, 2011
by Rick_S
Rick_S's Avatar

I'll reiterate something I said long ago. Those transmitters sold by sure are NOT legal for use in some of the frequencies they transmit without proper licensing if you reside in the United States. The Amatuer radio band (70cm) covers 420MHz to 450MHz. If you set those transmitters to use frequencies within that range you would be breaking the law within the US if you do not have a license.

Frequencies above that may be ok, but if you want to be 100% you should check with your local authorities or contact the FCC.

Outside the US, I'm not sure what the frequency allocations are, and you would need to check with your local/government to find our available public frequencies.

Will you get caught and get in trouble???? Probably not, however 99 times out of 100 you may not get caught speeding... but when you do... those fines can suck.

Now if you have an amatuer license... Those frequencies are open to you (as you would know).


December 25, 2011
by kle8309
kle8309's Avatar

I finally finished with a series of tutorials concerning serial communication and Visual Studio C#. I hope this will help anyone who wants to learn how to get started with building a GUI for their embedded project.

serial COM tutorial

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