Introduction:
This section is the control unit of the whole project. It basically consists of a Micro controller with its associated circuitry like Crystal with capacitors, Reset circuitry, Pull up resistors (if needed) and so on. The Micro controller forms the heart of the project because it controls the devices being interfaced and communicates with the devices according to the program being written.
A Micro controller consists of a powerful CPU tightly coupled with memory
RAM, ROM or EPROM), various I / O features such as Serial ports, Parallel
Ports, Timer/Counters, Interrupt Controller, Data Acquisition interfaces-Analog
to Digital Converter (ADC), Digital to Analog Converter (ADC), everything
integrated onto a single Silicon Chip.
Micro controller has memory such as RAM, ROM or EPROM and peripherals on a single chip so development of a similar system with a micro controller reduces PCB size and cost of the design.
Micro controller use in the project.
PIC16f877A
This devices are available in 40-pin packages is shown as picture below.
PIC16f877a
Device features.
Port Function.
In this project each PORT of pin have it own function.
PORT A = Analog to Digital input.
Measurement of analogue
variables such as voltage and current must be converted to digital signals in order
to be processed by the microcontroller. This microcontrollers have built in
analogue to digital converters (ADC), enabling the analogue signals to be fed
directly into the input pins of the microcontroller.
PORT B = It use as keypad interface and interrupt function.
PORT C = additional input/output
PORT D = Use as interfacing LCD
