Microcontroller, Electrical Dost

Definition: Microcontroller is a single-chip microcomputer that has everything inbuilt.

Why Microcontrollers are developed?
Ans. Due to varieties of memory and I/O devices, the hardware design of a microprocessor is arranged so that a very small or very large system can be configured around the CPU depending on the application of the user. For a small application, the minimum size of memory and I/O must be interfaced with the CPU. this increases the hardware. In turn, the PCB size and cost of the system also increases.

The microcontroller is optimized for specific applications. It consists of all the features of a microprocessor as well as the features required to build a complete computer.

Microcontroller components: the microcontroller has on-chip on-chip peripheral devices and memory. They are from RAM, ROM, serial I/O, parallel I/O, timer/counters, interrupt and clock. These on-chip peripherals make it possible to house a single-chip microcomputer system.

The general architecture of Microcontroller.

Microcontroller, Electrical Dost
Historical evolution of Microcontroller

Like the developments of microprocessor 4, 8, 16 and 32 bit, microcontrollers have also developed and appeared in the market.

Microcontroller, Electrical Dost
Classification of Microcontrollers

Like the developments of microprocessor 4, 8, 16 and 32 bit, microcontrollers have also developed and appeared in the market.

1) 8 Bit Microcontrollers
In 1974 Texas instruments introduced first microcontroller TMS 1000. In 1976 Intel introduced the first microcontroller intel 8048. When the internal bus of the microcontroller is 8 bits, the ALU can perform arithmetic and logic operations on a byte at an instruction. Such a microcontroller is called as an 8-bit microcontroller. 8-bit Microcontrollers have dominated over 16-bit Microcontrollers. This is because most of the designer is familiar with 8-bit microcontroller 16-bit operation that can be done on an 8-bit Microcontrollers by programming them. The ASCII data is stored in an 8-bit format. So, 8 bits are generally used for data communication. Also interfacing 8 bits with memory ICs is easy.

2) 16-bit Microcontrollers
If the internal bus in a microcontroller is 16 bit, the ALU performs arithmetic and logic operations on a word of 16 bits at an instruction. Such a microcontroller is called a 16-bit microcontroller. eg. intel 8096. They are designed for high-performance applications. The 16-bit Microcontrollers have a large program and data memory spaces. They have flexible I/O and peripheral capabilities.

3) 32-bit microcontrollers
When the internal bus for the data transfer operations in a microcontroller is 32 bit and the ALU performs arithmetic and logic operations on a word of 32bits at an instruction, the microcontroller is a 32-bit. eg. Armed 25/family, Intel 80960, Motorola M683XX, ARM 7 or ARM 9 orARM 11 processors. They provide greater precision and performance as compared to 16-bit microcontrollers.


Microcontrollers are widely used in embedded system products to obtain a particular task.

  • Some applications of embedded products using microcontrollers given below.

Applications in office :
1) telephones
2) computers
3) security systems
4) Copier
5) Laser pointer
6) Colour printer

Applications in home :
1) Appliances
2) Telephones
3) Security systems
4) Intercom
5) Garage door openers
6) Answering machine
7) Fax machines
8) Home computer
9) TVs
10) Cable TV tuner
11) VCR
12) Camcorder
13) Remote control
14) Video games
15) Cellular phones
16) Musical instruments
17) Sewing machines
18) Lighting control
19) paging
20) Toys
21) Camera
22) Exercise equipment

Applications in automation :
1) Trip computer
2) instrumentation
3) climate control
4) engine control
5) security system
6) cellular phones
7) air bag
8) transmission control
9) keyless entry

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