Introduction to Microcontroller

Introduction to Microcontroller

To start basic understanding we need to memorise some important terms. 

The unit of data size

• Bit : a binary digit that can have the value 0 or 1
• Byte : 8 bits
• Nibble : half of a bye, or 4 bits
• Word : two bytes, or 16 bits

The terms used to describe amounts of memory in IBM PCs and compatibles

• Kilobyte (K): 2¹⁰ bytes
• Megabyte (M) : 2²⁰ bytes, over 1 million
• Gigabyte (G) : 2³⁰ bytes, over 1 billion
• Terabyte (T) : 2⁴⁰ bytes, over 1 trillion

CPU (Central Processing Unit)

•  Execute information stored in memory

I/O (Input/output) devices

• Provide a means of communicating with CPU

Memory

• RAM (Random Access Memory) – temporary storage of programs that computer is running
• The data is lost when computer is off
• ROM (Read Only Memory) – contains programs and information essential to operation of the computer
• The information cannot be changed by use, and is not lost when power is off
• It is called nonvolatile memory

CPU communication with other devices

Registers

• The CPU uses registers to store information temporarily
• Values to be processed
• Address of value to be fetched from memory
• In general, the more and bigger the registers, the better the CPU
• Registers can be 8-, 16-, 32-, or 64-bit
• The disadvantage of more and bigger registers is the increased cost of such a CPU

8051 MICROCONTROLLERS

General-purpose microprocessors contains

• No RAM
• No ROM
• No I/O ports

Microcontroller has

• CPU (microprocessor)
• RAM
• ROM
• I/O ports
• Timer/Counter
• ADC and other peripherals

The 8051 had

• 128 bytes of RAM
• 4K bytes of on-chip ROM
• Two timers
• One serial port
• Four I/O ports, each 8 bits wide
• 6 interrupt sources

Feature	8051
ROM (on-chip program space in bytes)	4K
RAM (bytes)	128
Timers	2
I/O pins	32
Serial port	1
Interrupt sources	6