This document provides information about a wireless serial communication RF modem module that operates at 2.4 GHz with a range of 30 meters. It can transmit and receive data at multiple baud rates and supports half-duplex communication. The module has features such as multiple channel selection, operation in the unlicensed 2.4 GHz band, and a standard UART interface. Example applications and specifications are also provided, along with code samples for interfacing the module with an 8051 microcontroller and a PC.

1. 1
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Wireless Serial Communication RF Modem, 2.4 GHz, 30 meter range
Overview
CC2500 RF Module is a Transreceiver module which provides easy to use RF communication at 2.4 GHz. It can be used to transmit and receive data at multiple baud rates from any standard CMOS/TTL source. It works in Half Duplex mode i.e. it provides communication in both directions, but only one direction at same time (not simultaneously). This switching from receiver to transmitter mode is done automatically.
RF Module can be used for applications that need two way wireless data transmission. It features high data rate and longer transmission distance. The communication protocol is self controlled and completely transparent to user interface. The module can be embedded to your current design so that wireless communication can be set up easily.

2. 2
Features
 Supports Multiple Baud rates (4800/9600/19200/38400).
 Supports Multiple Channel Selection (CH0/CH1/CH2/CH3).
 Works on ISM band (2.4 GHz) which is reserved internationally so no need to apply for license.
 No complex wireless connection software or intimate knowledge of RF is required to connect your serial devices.
 Designed to be as easy to use as cables.
 No external Antenna required.
 Plug and play device.
 Works on 5-9v DC supply.
 Standard UART Interface.
Applications
 Consumer electronics.
 Wireless game controllers.
 Wireless keyboard and mouse.
 Weather stations.
 Sensor Networks / Data collection.
 Wireless metering.
 RF enabled remote controls.
 Access control / Identity discrimination.
 Wireless data link (communication).
 Wireless audio.
 IT home appliance.
 Smart house products / Security Systems.
 Remote control / Remote measurement system.

3. 3
Specifications
Parameter Min Typ Max Units
Working Voltage
4.5
5
9
Volts
Frequency
2.4
GHz
Range
30
Meters
UART baud rate (8 bit data, no parity, 1 stop bit) (1)
4800/9600/19200/38400
bps
Frequency channel (1)
CH0/CH1/CH2/CH3
-
Maximum Data Transmission (2)
32
Characters
Note:
1. Baud Rate & Frequency Channel Settings depends on DIP Switch Position. (Refer Page No. 5 &6)
2. Carriage Return (CR) is required at the end of string for successful data transmission.

4. 4
Pin Diagram
Pin Pin Name Pin Name
RX
Receive Input
Input serial data of 3 to 5V logic level
TX
Transmit Output
Output serial data of 3V logic level
+5V
Power Supply
Regulated 5V supply input
Gnd
Ground
Ground level of power supply
Operation
This module works in half-duplex mode. Means it can either transmit or receive but not both at same time. After each transmission, module will be switched to receiver mode automatically. The LED for TX and RX indicates whether IC is currently receiving or transmitting data. The data sent is checked for CRC error if any. The RX LED is directly on TX OUT pin to indicate that actual data is received and it is sent to output pin.
Settings
The module supports multiple baud rates and multiple frequency channels. The settings will take place only during power on i.e. you will have to restart the module every time you change the setting. Modifying during power up will have no effect on operation of module.
DIP switch number 1 & 2 are used to set the baud rate whereas DIP switch number 3 & 4 are used to select channel frequency.

5. 5
Frequency Channel Setting
Setting Frequency Channel can be used to have multiple sets operating at same time but without Interfering with each other. The pair having same Channel setting will be able to communicate with each other. Thus avoiding data collision between multiple set of modules.
Frequency channel has to be set when module is OFF, as the switch positions are read only during power up. Modifying this setting during operation will have no effect on operation of module.
Channel settings mentioned in table given below are for Baud rate 9600 bps.
Switch Channel Setting
Channel =0
Channel =1
Channel =2
Channel =3

6. 6
Baud Rate Setting
Baud rate has to be set when module is OFF, as the switch positions are read only
during power up. Modifying this setting during operation will have no effect on
operation of module.
Baud rate settings mentioned in table given below are for Channel 0.
Switch
Baud Rate Setting
9600 bps
38400 bps
19200 bps
4800 bps

7. 7
Interfacing with 8051 Microcontroller

8. 8
Code
LCD will display data received & send string “received” as an acknowledgement. Here baud rate setting is 9600.
#include<reg52.h>
#include <string.h>
#define cmdport P2
#define dataport P0
unsigned char ntc[32];
unsigned char current_byte = 0;
unsigned char icnt = 0;
sbit rs = cmdport^6; //register select pin
//sbit rw = cmdport^1; // read write pin
sbit e = cmdport^7; //enable pin
void ser_init(void);
void Delay250us (void);
void MsDelay (int n);
void read_ntc(void);
void lcdcmd(unsigned char item);
void lcddata(unsigned char item);
void lcdstr(unsigned char *s);
void lcdinit(void);
void Delay250us (void)
{
int j ;
for(j = 0 ; j < 100 ; j ++)
{
}
}
void MsDelay (int n)
{
int j ;
for(j = 0 ; j < n ; j ++)
{
Delay250us() ;
Delay250us() ;
Delay250us() ;
Delay250us() ;
}
}
void ser_init(void)
{
TMOD=0x20; //Timer 1 Mode 2

9. 9
TH1=-3; // Bouad Rate-9600
SCON=0x050; // 8 bit,1 stop bit
TR1=1; // start timer
ES = 1; // enable serial interrupts
}
void recieve() interrupt 4 using 1 // Function to recieve data serialy from RS232
{
if (RI)
{
ntc[ current_byte]=SBUF;
RI=0;
current_byte++;
}
}
void Ser_Write_Text(unsigned char *str)
{
unsigned char l,i;
l = strlen(str)+1; // get the length of string
for(i=1;i<l;i++)
{
SBUF=*str; // send every char one by one
while(TI==0);
TI=0;
str++;
}
}
void ser_write_no(unsigned int no)
{
SBUF=no;
while(TI==0);
TI=0;
}
void read_ntc(void) // Function to display the received string
{
unsigned char count;
lcdcmd(0x01);
MsDelay(10);
lcdcmd(0x80);
MsDelay(10);
for(count=0;count<current_byte;count++)
{
lcddata(ntc[count]);

10. 10
if (count==15)
{
lcdcmd(0xC0);
MsDelay(10);
}
}
current_byte=0;
}
//Function to send command to LCD
void lcdcmd(unsigned char item)
{
dataport = item;
rs= 0;
//rw=0;
e=1;
MsDelay(1);
e=0;
}
//Function to send data to LCD
void lcddata(unsigned char item)
{
dataport = item;
rs= 1;
//rw=0;
e=1;
MsDelay(1);
e=0;
}
//Function to display string
void lcdstr(unsigned char *s)
{
unsigned char l,i;
l = strlen(s); // get the length of string
for(i=1;i<=l;i++)
{
lcddata(*s); // write every char one by one
s++;
}
}
//Function to initialise LCD
void lcdinit(void)
{

11. 11
lcdcmd(0x38); // for using 8-bit 2 row mode of LCD
MsDelay(10);
lcdcmd(0x0E); // turn display ON for cursor blinking
MsDelay(10);
lcdcmd(0x01); //clear screen
MsDelay(10);
lcdcmd(0x06); //display ON
MsDelay(10);
}
void main()
{
EA = 1; /* enable global interrupts */
lcdinit();
MsDelay(10);
lcdcmd(0x80);
MsDelay(10);
lcdstr("CC2500");
lcdcmd(0xC0);
MsDelay(10);
lcdstr("Interface");
MsDelay(100);
ser_init();
MsDelay(50);
while(1)
{
while(current_byte==0);
read_ntc();
current_byte=0;
Ser_Write_Text("Recieved");
ser_write_no(13);
MsDelay(10);
}
}

12. 12
Interfacing with PC
Code
Code is written inVB.NET 2010 for transmitting & reception of data to & from
CC2500 module. Here baud rate setting is 9600 bps.

13. 13
Imports System
Imports System.IO.Ports
Public Class Form1
Dim WithEvents port As SerialPort = New _
System.IO.Ports.SerialPort("COM3", 9600, Parity.None, 8, StopBits.One)
Private Sub Form1_Load(ByVal sender As Object, ByVal e As _
System.EventArgs) Handles Me.Load
CheckForIllegalCrossThreadCalls = False
If port.IsOpen = False Then port.Open()
End Sub
Private Sub port_DataReceived(ByVal sender As Object, ByVal e As _
System.IO.Ports.SerialDataReceivedEventArgs) Handles port.DataReceived
Label1.Text = port.ReadExisting
End Sub
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
port.Write(TextBox1.Text & vbCr)
End Sub
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
Application.Exit()
End Sub
End Class