What is a Microcontroller ?  

A Microcontroller is a programmable digital processor with necessary peripherals. Both microcontrollers and microprocessors are complex sequential digital circuits meant to carry out job according to the program / instructions.


Development/Classification of microcontrollers

In 1993, the introduction of EEPROM allows microcontrollers (beginning with the Microchip PIC16x840) both rapid prototyping and In-System-Programming (ISP). The same year, the first microcontroller using Flash memory was introduced by Atmel.

                      For most embedded systems, we have the choice between 4-bit, 8-bit, 16-bit and 32-bit cores. 4-bit microcontrollers are extensively used in electronic toys. 8-bit microcontrollers are generally used in various control applications such as position control, speed control and any process control system. The 16-bit microcontroller are designed and developed for the purpose of high speed control application such as servo control system, robotics etc. For very high speed operations in robotics, image processing, automobiles, intelligent control system and telecommunications 32- bit microcontrollers are used.

                    Microcontrollers have gone through a silent evolution. The evolution of microcontroller technology has undergone significant change since early 1970’s. Development of some popular microcontrollers is given as follows:

Intel 4004 4 bit (2300 PMOS trans, 108 kHz) 1971
Intel 8048 8 bit 1976
Intel 8031 8 bit (ROM-less) .
Intel 8051 8 bit (Mask ROM) 1980
Microchip PIC16C64 8 bit 1985
Motorola 68HC11 8 bit (on chip ADC) .
Intel 80C196 16 bit 1982
Atmel AT89C51 8 bit (Flash memory) .
Microchip PIC 16F877 8 bit (Flash memory + ADC) .


Classification of different microcontroller chips could be as follows:

  • Embedded (Self -Contained) 8 – bit Microcontroller
  • 16 to 32 Microcontrollers
  • Digital Signal Processors

What types of microcontrollers are there ? Nowadays

  • 8051 – The ‘8051 core’ was one of the most popular standard in 8-bit microcontrollers ever with large derivatives, extra features & vast community support. Developed by Intel in the 1980s, it still seems to be the instruction set they love to teach you in college & used till date in many applications.
  • PIC – This is the classic microcontrollers from Microchip. Very simple, very proven, but it lacks many of the features that other manufacturers are building into their chips.
  • AVR – This is basically a direct competitor of PICs. They do everything a PIC does, but in my opinion, better, faster, cheaper, simpler, & with wide community support.
  • MSP – These are very good microcontrollers by Texas Instruments (TI), not as beefy as AVR or PICs. However they are popular for low-power applications. Imagine running a complete system on single AA battery for 5 years. This is in the realm of nano-amp current consumption. Awesum !
  • ARM – What  am i say about this is, only “Mighty Monster”. I don’t want discuss the features of ARM because its enormous. They are taking over the world but can be really intimidating if you’ve never played with any microcontrollers before.

How does microcontroller works?

Let we understand by example of washing machine

Following points classifies washing machine in complex manners

  1. Input panel – include buttons of water management, heater management, spinning time, etc.
  2. Display panel – shows what action have you selected and status of machine, etc.
  3. Output devices – motor, heater, pipes(inlet & outlet for water), etc.
  4. Control unit – this is where our engineering introduce, “MICROCONTROLLER”. Which control all these resources like motor, heater, display & inputs.

                            Now, as we all knows that microcontroller is digital sequecial logic means it work in digital input & output logics ,in terms of 1’s & 0’s (accept ADCs and all).

  • So your first question is how this small chip of microcontroller which is just generating 0’s & 1’s is going to controlling large washing machine.
  • Well, answer is simple “Embedded System Design Engineering”

                          Let me explain this control unit (microcontroller) in simple way. Microcontroller take input from switches and other things attached to washing machine by using its pins, which is in 1’s & 0’s form, simply 1 mean +5V (ON) and 0 mean 0V (OFF), process that input data according to program stored in that particular microcontroller and gives output (simply make them ON-OFF) to  motors, heater & other things attached to it . And displays status of machine and other things that already programmed in your controller by display panel

                         So in general, Microcontrollers have different pins, which works as input, output & other special function (like communication protocol, PWM generation, ADC, etc ). These pins are configured by programming as it set to input, output or any other special functions & we carried out our work in intelligent manner with preprogrammed software (actually firmware) stored in microcontroller.


Microcontrollers are used in enormous amounts of applications. just look around and see any smart product, you will find microcontroller inside or at least one. Typical example of microcontroller based system is mobile phones, washing machines, TVs , computers, microwave oven, etc.

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