Introduction in microcontroller

Introduction

about

Microcontroller Eng :/ Sayed Mahmoud AbdEl Rahman

What is the Microcontroller ?

A microcontroller is an integrated chip that is often part

of an embedded system. The microcontroller includes

a CPU, RAM, ROM, I/O ports, and timers like a standard

computer, but because they are designed to execute only

a single specific task to control a single system,

they are much smaller and simplified so that they

can include all the functions required on a single chip.

Microcontroller v/s Microprocessor

Microprocessors are used to execute big and generic applications,

while a microcontroller will only be used to execute a single task

within one application. Some of the benefits of microcontrollers

include the following:

Cost: The cost of the part. Microcontrollers are usually very cheap,

sometimes even less than $1 each.

Speed: The frequency (speed) of the system clock, often stated in

megahertz (MHz) or gigahertz (GHz). Microcontrollers are typically

slow, less than 20MHz.

Power: The power dissipation of a system, measured in Watts.

Microcontrollers are almost always "low-power."

Bits: This usually means the number of bits that can be processed

at one time by each instruction (e.g. 8-bit, 16-bit, 32-bit, etc...).

Microcontrollers are almost always 8-bit or maybe 16-bit devices.

Memory: Most processors have some amount of storage on the device

for data and program instructions. In computing systems, memory is

often hierarchical, so on-chip memory can serve different purposes.

Microcontrollers typically have a limited amount of memory, less

than 1MByte total.

All-in-one: A microcontroller usually Includes of a CPU, ROM,

RAM and I/O ports, built within it to execute a single and dedicated

task. On the other hand, a microprocessor generally does not have a

RAM, ROM or IO pins and generally uses its pins as a bus to interface

to peripherals such as RAM, ROM, serial ports, digital and analog IO.

How does Microcontroller work ?

Microcontroller has an input device in order to get the input and an

output device (such as LED or LCD Display) to exhibit the final

process. Let us look into the illustration of how a microcontroller

works in a Television.

The Television has a remote control as an Input device and the TV

screen as the output device. The signal sent from the remote control is

captured by the microcontroller. The microcontroller controls the

channel selection, the amplifier system and picture tube adjustments

such as hue, brightness, contrast etc.

General architecture of a Microcontroller The architecture of a microcontroller depends on the application it is

built for. For example, some designs include usage of more than one

RAM, ROM and I/O functionality integrated into the package.

The architecture of a typical microcontroller is complex and may include

the following:

1. A CPU, ranging from simple 4-bit to complex 64-bit processers.

2. Peripherals such as timers, event counters and watchdog.

3. RAM (volatile memory) for data storage. The data is stored in the form of

registers, and the general-purpose registers store information that interacts

with the arithmetic logical unit (ALU).

4. ROM, EPROM, EEPROM or flash memory for program and operating

parameter storage.

5. Programming capabilities (Assembly, c, c++, Basic and Pascal) .

6. Serial input/output such as serial ports.

7. A clock generator for resonator, quartz timing crystal or RC circuit.

8. Analog-to-digital convertors.

9. Serial ports.

10. Data bus to carry information.

Applications

Microcontrollers are used in products that are controlled automatically.

The various products that make use of microcontrollers in our everyday

life are given below:

1. Home: Television, DVD player, Telephone, Fax machine, Cellular

phones, Security systems, Camera, Sewing machine, Musical

Instrument, Exercising machine, Video games, Computer,

Microwave oven.

2. Office: Computers, Printers, Telephones, Fax machine, Security

systems.

My Application on Microcontroller

Air Condition Control:

Hardware:

1-tansator (Temp Sensor).

2-Button.

3-Led.

4-LCD Display.

5-Microcontroller (PIC16F877A 8-bit).

6-Crystal 4MHz.

7-Capactor 0.1µF – 22PF – 3.3µF.

8-Resistance 10kΩ - 330 Ω.

Circuit Design by Eagle program

Layout Circuit

Software (Code by MikroC program):

Thanks