An embedded project is a combination of hardware and software, designed to perform a specific task. In embedded technology the embedded programming is burnt into the AT8C52 micro controller. The main scope of the project is mainly based on the advertising of applications using RF Modules.
In this project two Radio Frequency Modules are used, a transmitter module and receiver module. The transmitter Module consists of switches, encoder, RF Transmitter and PC. PC is connected to transmitter module which transmits the characters to the receiver module. At the other end the receiver consists of micro controller, decoder, RF receiver, and an LCD which receives data from the transmitter module and displays it on the LCD. The control operation of the system is done with the help of PC.
Radio Frequency (RF) is a frequency or rate of oscillation within the range of about 3 Hz to 300 GHz. In this project we are using a 433 MHz frequency RF module; this is a license free frequency so we can use it without owning a license. The range of this frequency can be up to 12 Km.
[...] Since most of this range is beyond the vibration rate that most mechanical systems can respond to, RF usually refers to oscillations in electrical circuits. The transmitter module consists of PC through which we give the input. An interfacing level is used to convert TTL logic to CMOS logic and is given to the AT89C52 micro controller. The data from the micro controller is given to the encoder which is given to the RF transmitter. From RF Transmitter the data is received by the RF Receiver through Radio frequencies. [...]
[...] HT640 application circuit: DECODER (HT 648L): Features: Operating voltage: 2.4 V~12V Low power and high noise immunity CMOS technology Low standby current Capable of decoding 18 bits of information Pairs with HOLTEK's 318 series of encoders 8~18 address pins 0~8 data pins Trinary address setting Two times of receiving check Built-in oscillator needs only a resistor Valid transmission indictor Easily interface with an RF or an infrared transmission medium Minimal external components Applications: Burglar alarm system Smoke and fire alarm system Garage door controllers Car door controllers Car alarm system Security system Cordless telephones Other remote control systems General Description: The 318 decoders are a series of CMOS LSIs for remote control system applications. They are paired with the 318 series of encoders. For proper operation a pair of encoder/decoder pair with the same number of address and data format should be selected (refer to the encoder/decoder cross reference tables). The 318 series of decoders receives serial address and data from that series of encoders that are transmitted by a carrier using an RF or an IR transmission medium. It then compares the serial input data twice continuously with its local address. [...]
[...] External program memory and external data memory can be combined by applying the RD and PSEN signal to the inputs of AND gate and using the output of the fate as the read strobe to the external program/data memory. MCS-51 devices have a separate address space for Program and Data Memory. Up to 64K bytes each of external Program and Data Memory can be addressed. Program Memory : If the EA pin is connected to GND, all program fetches are directed to external memory. [...]
[...] RF transmitters are used in a variety of applications and industries. Often, devices that are used with integrated circuits (ICs) incorporate surface mount technology through hole technology and flat pack. In the telecommunications industry, RF transmitters are designed to fit in a metal rack that can be installed in a cabinet. RF transmitters are also used in radios and in electronic article surveillance systems (EAS) found in retail stores. Inventory management systems use RF transmitters as an alternative to barcodes. [...]
[...] LIQUID CRYSTAL DISPLAY: The alphanumeric 16character X 2line LCD requires 8data lines and also 3 control signals and they are interfaced to 3664.By using 2 ports, port 0&3 data pins are connected to LCD as data bus. Port0 can be basically used as I/O port i.e. it can be programmed as an input or as an output port. That means if it is programmed as output port, suppose if it is required to read data from LCD immediately it is not possible. [...]
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