RF Serial Data Link UART, 2.4 GhzPIC+CC2500 based, around 30 meters range.
RF data modem working at 2.4 Ghz frequency in half duplex mode with automatic switching of receive/transmit mode with LED indication. Receives and Transmits serial data of adjustable baud rate of 9600/4800/2400/19200 bps at 5V or 3V level for direct interfacing to microcontrollers. This model can work with other 2.4 Ghz Sunrom models 1253(RS232) or 1252(USB).
RF modem 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.
- Automatic switching between TX and RX mode.
- FSK technology, half duplex mode, robust to interference.
- 2.4 GHz band, no need to apply frequency usage license.
- Protocol translation is self controlled, easy to use.
- High sensitivity, reliable transmission range.
- Standard UART interface, TTL(3-5V) logic level.
- Stable, small size, easier mounting.
- No tuning required, PLL based self tuned.
- Error checking(CRC) of data in built.
- Sensor Networks / Data collection
- Wireless metering
- Access control / Identity discrimination
- IT home appliance
- Smart house products / Security Systems
- Remote control / Remote measurement system
- Weather stations
Board Layout and Schematic
When setting a RF serial data communication between microcontrollers or a microcontroller to PC, the RF modem is most useful and easy to implement.
- Working voltage 4.5 to 9V (Typical 5V)
- Frequency 2.4 Ghz
- Output RF Power 1 dBm
- Typical Operating Range: 30-50 meters
- UART baud rate (8 bit data, no parity, 1 stop bit) 9600/4800/2400/19200 bps
- RXD = Receive Input: Input serial data of 3 to 5V logic level, Usually connected to TXD pin of microcontrollers.
- TXD = Transmit Output: Output serial data of 3V logic level, Usually connected to RXD pin of microcontrollers.
- +5V = Regulated 5V supply input.
- GND = Ground level of power supply. Must be common ground with microcontroller.
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. If chip is transmitting and any data is input to transmit, it will be kept in buffer for next transmission cycle. It has internal buffer for incoming data so they do not get lost when module is active transmiting data.
When you power on the unit, the TX LED will briefly blink indicating that initialization is complete and it is ready to use.
The RX LED is directly on TX OUT pin to indicate that actual data is received and it is sent to output pin.
Baud Rate Setting
Baud rate has to be set when unit is OFF, as the jumper setting are read only during power up. Modifying during power up will have no effect on operation of module. To make any jumper on, short that jumper by soldering its pads. By default unit is supplied with no jumper.
There are two jumpers on PCB called B1 and B2. Normally they are left open so unit is in 9600 baud rate. Solder the two pads to make them ON so you can configure baud rate as per settings below
- B2 = OFF B1 = OFF is 9600 bps (Default)
- B2 = OFF B1 = ON is 4800 bps
- B2 = ON B1 = OFF is 2400 bps
- B2 = ON B1 = ON is 19200bps
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. Frequency channel has to be set when unit is OFF, as the jumper are read only during power up. Modifying this setting during operation will have no effect on operation of module. To make any jumper on, short that jumper by soldering its pads. By default unit is supplied with no jumpers set making it channel#1.
- F2 = OFF F1 = OFF is Channel #1 (Default)
- F2 = OFF F1 = ON is Channel #2
- F2 = ON F1 = OFF is Channel #3
- F2 = ON F1 = ON is Channel #4
Interfacing UART Serial Data by various methods
To Interfacing with PC's Serial port, which has RS232 level(+/-12V) the output from board needs to be converted to RS232 level by using MAX232 IC. Then the data is connected to PC's RS232 port. Board+MAX232 will need external +5V power supply and ground has to be common between both boards.
One advantage of using USB to interface is you can use power supply from USB itself.
Interfacing with any microcontroller is easy. Just configure your micro to proper baud rate and transmit receive data.
Terminal Software on PC
For reading and transmitting by serial port, We find Terminal software to be most versatile, Flexible and Stable during development phase.