Microcontrollers Types & Their Applications

A microcontroller is a single chip and it is denoted with μC or uC. The fabrication technology used for its controller is VLSI. An alternate name of the microcontroller is the embedded controller. At present, there are different microcontrollers types that are existing in the market like 4-bit, 8-bit, 64-bit & 128-bit. It is a compressed microcomputer used to control the embedded system functions in robots, office machines, motor vehicles, home appliances & other electronic gadgets. The different components used in a microcontroller are a processor, peripherals, & memory. These are basically used in different electronic devices that require an amount of control to be given by the operator of the device. This article discusses an overview of microcontrollers types and their working.

What is a Microcontroller?

A microcontroller is a small, low-cost, and self-contained computer-on-a-chip that can be used as an embedded system. A few microcontrollers may utilize four-bit expressions and work at clock rate frequencies, which usually include:

  • An 8 or 16-bit microprocessor.
  • A little measure of RAM.
  • Programmable ROM and flash memory.
  • Parallel and serial I/O.
  • Timers and signal generators.
  • Analog to Digital and Digital to Analog conversion

Microcontrollers usually must have low-power requirements since many devices they control are battery-operated. Microcontrollers are used in many consumer electronics, car engines, computer peripherals, and test or measurement equipment. And these are well suited for long-lasting battery applications. The dominant part of microcontrollers being used nowadays is implanted in other apparatus.

Microcontrollers Working

The microcontroller chip is a high-speed device, but as compared with a computer it is slow. Thus each instruction will be executed within the microcontroller at a quick speed. Once the supply is turned ON, then the quartz oscillator will be activated through the control logic register. For a few seconds, as the early preparation is in development, then parasite capacitors will be charged.

Once the voltage level achieves its highest value & oscillator’s frequency turns into the stable process of writing bits over special function registers. Everything happens based on the CLK of the oscillator & overall electronics will start working. All this takes extremely few nanoseconds.

The main function of a microcontroller is, it can be considered like self-contained systems using a processor memory. Its peripherals can be utilized like an 8051 Microcontroller. When the microcontrollers majority in use at present are embedded within other kinds of machinery like telephones appliances, automobiles & computer systems peripherals.


Basics of Microcontrollers Types

Any electric appliance used to store, measure & display the information otherwise measures comprise of a chip in it. The microcontroller’s basic structure includes different components.


The microcontroller is called a CPU device, used to carry & decode the data & finally completes the allocated task effectively. By using a central processing unit, all the microcontroller components are connected to a particular system. Instruction fetched through the programmable memory can be decoded through the CPU.


In a microcontroller, the memory chip works like a microprocessor because it stores all the data as well as programs. Microcontrollers are designed with some amount of RAM/ROM/flash memory to store the program source code.

I/O Ports

Basically, these ports are used to interface otherwise drive different appliances like LEDs, LCDs, printers, etc.

Serial Ports

Serial ports are used to provide serial interfaces between microcontroller as well as a variety of other peripherals like parallel port.


A microcontroller includes timers otherwise counters. These are used to manage all the operations of timing and counting in a microcontroller. The main function of the counter is to count outside pulses whereas the operations which are performed through timers are clock functions, pulse generations, modulations, measuring frequency, making oscillations, etc.

ADC (Analog to Digital Converter)

ADC is the acronym of analog to digital converter. The main function of ADC is to change the signals from analog to digital. For ADC, the required input signals are analog and the production of a digital signal is used in different digital applications like measurement devices

DAC (Digital to Analog Converter)

The acronym of DAC is digital to analog converter, used to perform reverse functions to ADC. Generally, this device is used to manage analog devices such as DC motors, etc.

Interpret Control

This controller is employed to give delayed control to a running program & interpretation is either internal otherwise external.

Special Functioning Block

Some special microcontrollers designed for special devices like robots, space systems include a special function block. This block has extra ports to carry out some particular operations.

How are Microcontrollers Types Classified?

The microcontrollers are characterized regarding bus-width, instruction set, and memory structure. For the same family, there may be different forms with different sources. This article is going to describe some of the basic types of Microcontroller that newer users may not know about.

The types of the microcontroller are shown in the figure, they are characterized by their bits, memory architecture, memory/devices, and instruction set. Let’s discuss briefly it.

Types of Microcontrollers
Types of Microcontrollers

Microcontrollers Types According to the Number of Bits

The bits in the microcontroller are 8-bits, 16-bits, and 32-bits microcontroller.

In an 8-bit microcontroller, the point when the internal bus is 8-bit then the ALU performs the arithmetic and logic operations. The examples of 8-bit microcontrollers are Intel 8031/8051, PIC1x, and Motorola MC68HC11 families.

The 16-bit microcontroller performs greater precision and performance as compared to the 8-bit. For example, 8-bit microcontrollers can only use 8 bits, resulting in a final range of 0×00 – 0xFF (0-255) for every cycle. In contrast, 16-bit microcontrollers with their bit data width have a range of 0×0000 – 0xFFFF (0-65535) for every cycle.

A longer timer’s most extreme worth can likely prove to be useful in certain applications and circuits. It can automatically operate on two 16 bit numbers. Some examples of the 16-bit microcontrollers are 16-bit MCUs are extended 8051XA, PIC2x, Intel 8096, and Motorola MC68HC12 families.

The 32-bit microcontroller uses the 32-bit instructions to perform the arithmetic and logic operations. These are used in automatically controlled devices including implantable medical devices, engine control systems, office machines, appliances, and other types of embedded systems. Some examples are Intel/Atmel 251 family, PIC3x.

Microcontrollers Types According to Memory Devices

The memory devices are divided into two types, they are

  • Embedded memory microcontroller
  • External memory microcontroller

Embedded Memory Microcontroller: When an embedded system has a microcontroller unit that has all the functional blocks available on a chip is called an embedded microcontroller. For example, 8051 having program & data memory, I/O ports, serial communication, counters and timers and interrupts on the chip is an embedded microcontroller.

External Memory Microcontroller: When an embedded system has a microcontroller unit that has not all the functional blocks available on a chip is called an external memory microcontroller. For example, 8031 has no program memory on the chip is an external memory microcontroller.

Microcontrollers Types According to Instruction Set

CISC: CISC is a Complex Instruction Set Computer. It allows the programmer to use one instruction in place of many simpler instructions.

RISC: The RISC stands for Reduced Instruction set Computer, this type of instruction sets reduces the design of microprocessor for industry standards. It allows each instruction to operate on any register or use any addressing mode and simultaneous access of program and data.

Example for CISC and RISC

CISC: Mov AX, 4         RISC: Mov AX, 0
Mov BX, 2 Mov BX, 4
ADD BX, AX Mov CX, 2
Begin ADD AX, BX
Loop Begin

From the above example, RISC systems shorten execution time by reducing the clock cycles per instruction, and CISC systems shorten execution time by reducing the number of instructions per program. The RISC gives a better execution than the CISC.

Microcontrollers Types According to Memory Architecture

The memory architecture of microcontroller are two types, they are namely:

  • Harvard memory architecture microcontroller
  • Princeton memory architecture microcontroller

Harvard Memory Architecture Microcontroller: The point when a microcontroller unit has a dissimilar memory address space for the program and data memory, the microcontroller has Harvard memory architecture in the processor.

Princeton Memory Architecture Microcontroller: The point when a microcontroller has a common memory address for the program memory and data memory, the microcontroller has Princeton memory architecture in the processor.

Microcontrollers Types

There are different microcontroller types like 8051, PIC, AVR, ARM,

Microcontroller 8051

It is a 40pin microcontroller with Vcc of 5V connected to pin 40 and Vss at pin 20 which is kept 0V. And there are input and output ports from P1.0 – P1.7 and which having an open-drain feature. Port3 has got extra features. Pin36 has the open-drain condition and pin17 has internally pulled up transistor inside the microcontroller.

When we apply logic 1 at port1 then we get logic 1 at port21 and vice versa. The programming of the microcontroller is dead complicated. Basically, we write a program in C-language which is next converted to machine language understood by the microcontroller.

A RESET pin is connected to pin9, connected with a capacitor. When the switch is ON, the capacitor starts charging and RST is high. Applying a high to the reset pin resets the microcontroller. If we apply logic zero to this pin, the program starts execution from the beginning.

Memory Architecture of 8051

The memory of 8051 is divided into two parts. They are Program Memory and Data Memory. Program Memory stores the program being executed whereas Data Memory temporarily stores the data and the results. The 8051 has been in use in a wide number of devices, mainly because it is easy to integrate into a device. Microcontrollers are mainly used in energy management, touch screen, automobiles, and medical devices.

Program Memory of 8051
Program Memory of 8051


Data Memory of 8051
Data Memory of 8051


Pin Description of 8051 Microcontroller

Pin-40: Vcc is the main power source of +5V DC.

Pin 20: Vss – it represents the ground (0 V) connection.

Pins 32-39: Known as Port 0 (P0.0 to P0.7) to serving as I/O ports.

Pin-31: Address Latch Enable (ALE) is used to demultiplex the address-data signal of port 0.

Pin-30: (EA) External Access input is used to enable or disable external memory interfacing. If there is no external memory requirement, this pin is always held high.

Pin- 29: Program Store Enable (PSEN) is used to read signals from external program memory.

Pins- 21-28: Known as Port 2 (P 2.0 to P 2.7) – in addition to serving as I/O port, higher order address bus signals are multiplexed with this quasi bi directional port.

Pins 18 and 19: Used to interfacing an external crystal to provide a system clock.

Pins 10 – 17: This port also serves some other functions like interrupts, timer input, control signals for external memory interfacing Read and Write. This is a quasi bidirectional port with internal pull-up.

Pin 9: It is a RESET pin, used to set the 8051 microcontrollers to its initial values, while the microcontroller is working or at the initial start of the application. The RESET pin must be set high for 2 machine cycles.

Pins 1 – 8: This port does not serve any other functions. Port 1 is a quasi bi-directional I/O port.

Renesas Microcontroller

Renesas is the latest automotive microcontroller family that offers high-performance features with an exceptionally low power consumption over a wide and versatile extend of items. This microcontroller offers rich functional security and embedded safety characteristics required for new and advanced automotive applications. The core structure of the microcontroller CPU supports high reliability and high-performance requirements.

The full form of the RENESAS microcontroller is “Renaissance Semiconductor for Advanced Solutions”. These microcontrollers offer the best performance to microprocessors as well as microcontrollers to have good performance features along with its very-low power utilization as well as solid packaging.

This microcontroller has huge memory capacity as well as pinout, so these are utilized in different automotive control applications. The most popular microcontroller families are the RX as well as RL78 due to their high performance. The main features of RENESAS RL78, as well as RX family-based microcontrollers, include the following.

  • The architecture used in this microcontroller is CISC Harvard architecture which gives high performance.
  • The family of RL78 is accessible in 8-bit as well as 16bit microcontrollers whereas the RX family is a 32-bit microcontroller.
  • The RL78 family microcontroller is a low-power microcontroller whereas the RX family provides high efficiency as well as performance.
  • The RL78 Family microcontroller is available from 20 pins to 128 pins whereas the RX family is obtainable in a 48-pins microcontroller to a 176-pin package.
  • For the RL78 microcontroller, the flash memory ranges from 16KB to 512KB whereas, for the RX family, it is 2MB.
  • The RAM of the RX family microcontroller ranges from 2KB to 128KB.
  • The Renesas microcontroller offering low power, high performance, modest packages, and the largest range of memory sizes combined together with characteristics rich peripherals.
Renesas Microcontrollers
Renesas Microcontrollers
  • Renesas offers the most versatile microcontroller families in the world for example our RX family offers many types of devices with memory variants from 32K flash/4K RAM to an incredible 8M flash/512K RAM.
  • The RX Family of 32-bit microcontrollers is a feature-rich, general-purpose MCU covering a wide range of embedded control applications with high-speed connectivity, digital signal processing, and inverter control.
  • The RX microcontroller family uses a 32-bit enhanced Harvard CISC architecture to achieve very high performance.

Pin Description

Pin arrangement of Renesas microcontroller is shown in the figure:

Renesas Microcontrollers Pin Diagram
Renesas Microcontrollers Pin Diagram

It is a 20 pin microcontroller. Pin 9 is Vss, ground pin, and Vdd, power supply pin. It has three different kinds of interrupt, which are normal interrupt, fast interrupt, high-speed interrupt.

Normal interrupts store the significant registers on the stack by using push and pop instructions. The fast interrupts are automatically stored program counter and processor status word in special backup registers, so response time is faster. And high speed interrupts allocate up to four of the general registers for dedicated use by the interrupt to expand speed even further.

The internal bus structure gives 5 internal busses to ensure data handling is not slowed down. Instruction fetches occur via a wide 64-bit bus, so that due to the variable-length instructions used in CISC architectures.

Features and Benefits of the RX Microcontrollers

  • Low power consumption is realized using multi-core technology
  • Support for 5V operation for industrial and appliance designs
  • Scalability from 48 to 145 pins and from 32KB to 1MB flash memory, with 8KB of data flash memory included
  • Integrated safety feature
  • An integrated rich function set of 7 UART, I2C, 8 SPI, comparators, 12-bit ADC, 10-bit DAC and 24-bit ADC (RX21A), which will reduce system cost by integrating most functions

Application of Renesas Microcontroller

  • Industrial automation
  • Communication applications
  • Motor control applications
  • Test and measurement
  • Medical applications

AVR Microcontrollers

AVR microcontroller is developed by Alf-Egil Bogen and Vegard Wollan from Atmel Corporation. The AVR microcontrollers are modified Harvard RISC architecture with separate memories for data and program and the speed of AVR is high when compared to 8051 and PIC. The AVR stands for Alf-Egil Bogen and Vegard Wollan’s RISC processor.

Atmel AVR Microcontroller
Atmel AVR Microcontroller

Difference between 8051 and AVR Controllers

  • 8051s are 8-bit controllers based on CISC architecture, AVRs are 8-bit controllers based on RISC architecture
  • 8051 consumes more power than an AVR microcontroller
  • In 8051, we can program easily than the AVR microcontroller
  • The speed of AVR is more than the 8051 microcontroller

Classification of AVR Controllers

AVR Microcontrollers are classified into three types:

  • TinyAVR – Less memory, small size, suitable only for simpler applications
  • MegaAVR – These are the most popular ones having a good amount of memory (up to 256 KB), the higher number of inbuilt peripherals, and suitable for moderate to complex applications
  • XmegaAVR – Used commercially for complex applications, which require large program memory and high speed

Features of AVR Microcontroller

  • 16KB of In-System Programmable Flash
  • 512B of In-System Programmable EEPROM
  • 16-bit Timer with extra features
  • Multiple internal oscillators
  • Internal, self-programmable instruction flash memory up to 256K
  • In-system programmable using ISP, JTAG or high voltage methods
  • Optional boot code section with independent lock bits for protection
  • Synchronous/asynchronous serial peripherals (UART/USART)
  • Serial peripheral interface bus (SPI)
  • Universal serial interface (USI) for two/three-wire synchronous data transfer
  • Watchdog timer (WDT)
  • Multiple power-saving sleep modes
  • 10-bit A/D Converters, with a multiplex of up to 16 channels
  • CAN and USB controller support
  • Low-voltage devices operating down to 1.8v

There are many AVR family microcontrollers, such as ATmega8, ATmega16, and so on. In this article, we discussing the ATmega328 microcontroller. The ATmega328 and ATmega8 are pin-compatible ICs but functionally they are different. The ATmega328 has a flash memory of 32kB, where the ATmega8 has 8kB. Other differences are extra SRAM and EEPROM, the addition of pin change interrupts, and timers. Some of the features of ATmega328 are:

Features of ATmega328

  • 28-pin AVR microcontroller
  • Flash program memory of 32kbytes
  • EEPROM data memory of 1kbytes
  • SRAM data memory of 2kbytes
  • I/O pins are 23
  • Two 8-bit timers
  • A/D converter
  • Six-channel PWM
  • Inbuilt USART
  • External Oscillator: up to 20MHz

Pin Description of ATmega328

It comes in 28 pin DIP, shown in the figure below:

AVR Microcontrollers Pin Diagram
AVR Microcontrollers Pin Diagram

Vcc: Digital supply voltage.

GND: Ground.

Port B: Port B is an 8-bit bi-directional I/O port. The Port B pins are tri-stated when a reset condition becomes active or one, even if the clock is not running.

Port C: Port C is a 7-bit bi-directional I/O port with internal pull-up resistors.


Port D: It is an 8-bit bi-directional I/O port with internal pull-up resistors. The output buffers of Port D consist of symmetrical drive characteristics.

AVcc: AVcc is the supply voltage pin for the ADC.

AREF: AREF is the analog reference pin for the ADC.


Applications of AVR Microcontroller

There are many applications of AVR microcontrollers; they are used in home automation, touch screen, automobiles, medical devices, and defense.

PIC Microcontroller

PIC is a peripheral interface controller, developed by the general instrument’s microelectronics, in the year 1993. It is controlled by the software. They could be programmed to complete many tasks and control a generation line and many more. PIC microcontrollers are finding their way into new applications like smartphones, audio accessories, video gaming peripherals, and advanced medical devices.

There are many PICs, started with PIC16F84 and PIC16C84. But these were the only affordable flash PICs. Microchip has recently introduced flash chips with types that are much more attractive, such as 16F628, 16F877, and 18F452. The 16F877 is around twice the price of the old 16F84 but has eight times the code size, much more RAM, much more I/O pins, a UART, A/D converter, and a lot more.

PIC Microcontroller
PIC Microcontroller

Features of PIC16F877

The features of pic16f877 include the following.

  • High-performance RISC CPU
  • Up to 8K x 14 words of FLASH program memory
  • 35 Instructions (fixed-length encoding-14-bit)
  • 368×8 static RAM-based data memory
  • Up to 256 x 8 bytes of EEPROM data memory
  • Interrupt capability (up to 14 sources)
  • Three addressing modes (direct, indirect, relative)
  • Power-on reset (POR)
  • Harvard architecture memory
  • Power saving SLEEP mode
  • Wide operating voltage range: 2.0V to 5.5V
  • High sink / source current: 25mA
  • Accumulator based machine

Peripheral Features

3 timer/counters (programmable pre-scalars)

  • Timer0, Timer2 is 8-bit timer/counter with 8-bit pre-scalar
  •  Timer1 is 16-bit, can be incremented during sleep via external crystal/clock

Two capture, compare, PWM modules

  • Input capture function records the Timer1 count on a pin transition
  •  A PWM function output is a square wave with a programmable period and duty cycle.

10-bit 8 channel analog-to-digital converter

USART with 9-bit address detection

Synchronous serial port with master mode and I2C Master/Slave

The 8-bit parallel slave port

Analog Features

  • 10-bit, up to 8-channel Analog-to-Digital Converter (A/D)
  • Brown-out Reset (BOR)
  • Analog Comparator module (Programmable input multiplexing from device inputs and comparator outputs are externally accessible)

Pin Description of PIC16F877A

The pin description of PIC16F877A is discussed below.

PIC micro

PIC microcon

PIC microcontro

Advantages of PIC

  • It is a RISC design
  • Its code is extremely efficient, allowing the PIC to run with typically less program memory than its larger competitors
  • It is a low cost, high clock speed

A Typical Application Circuit of PIC16F877A

The circuit below consists of a lamp whose switching is controlled using a PIC microcontroller. The Microcontroller is interfaced with an external crystal which provides clock input.

PIC16F877A Microcontrollers Application
PIC16F877A Microcontrollers Application

The PIC is also interfaced with a push-button and on pressing the push button, the Microcontroller accordingly sends a high signal to the base of the transistor, so as to switch on the transistor and thus give proper connection to the relay to switch it on and allow passage of AC current to the lamp and thus the lamp glows. The status of the operation is displayed on the LCD interfaced to the PIC microcontroller.

MSP Microcontroller

A microcontroller like MSP430 is a 16-bit microcontroller. The term MSP is the acronym of “Mixed Signal Processor”. This microcontroller family is taken from Texas Instruments and designed for low cost as well as low power dissipation systems. This controller includes a 16-bit data bus, addressing modes-7 with reduced instructions set, which permits a denser, shorter, programming code used for quick performance.

This Microcontroller is one kind of integrated circuit, used to execute the programs to control other machines or devices. It is one kind of a micro-device, used to control other machines. The features of this microcontroller are normally obtainable with other kinds of the microcontroller.

  • Complete SoC like ADC, LCD, I/O ports, RAM, ROM, UART, watchdog timer, basic timer, etc.
  • It uses one external crystal and an FLL (frequency-locked loop) oscillator mainly derives all inner CLKs
  • Power utilization is low like 4.2 nW only for each instruction
  • Stable generator for the most frequently used constants like –1, 0, 1, 2, 4, 8
  • Typical high speed is 300 ns for each instruction like 3.3 MHz CLK
  • Addressing modes are 11 where the seven addressing modes are used for source operands & four addressing modes are used for destination operand.
  • RISC architecture with 27 core instructions

Real-time capacity is full, stable, and nominal system CLK frequency is obtainable after 6-clocks only once the MSP430 is restored from low-power mode. For the main crystal, no waiting to start stabilize & oscillation.

The core instructions were combined using special features to make the program easy within the MSP430 microcontroller using assembler otherwise in C to provide outstanding functionality as well as flexibility. For instance, even by using a low instruction count, the microcontroller is capable of following approximately the whole instruction set.

Hitachi Microcontroller

Hitachi microcontroller belongs to the H8 family. A name like H8 is used within a large 8-bit, 16-bit & 32-bit family of microcontrollers. These microcontrollers were developed through Renesas Technology. This technology was founded in Hitachi semiconductors, in the year 1990.

Motorola Microcontroller

Motorola microcontroller is an extremely incorporated microcontroller, used for data handling process with high-performance. The unit of this microcontroller uses a SIM (System Integration Module), TPU (Time Processing Unit) & QSM (Queued Serial Module).

Advantages of Microcontrollers Types

The advantages of microcontrollers types include the following.

  • Dependable
  • Reusable
  •  Energy-efficient
  • Cost-effective
  • Reusable
  • It requires less time to operate
  • These are flexible & very small
  • Because of their high integration, its size & cost of the system can be decreased.
  • Interfacing of the microcontroller is easy with additional ROM, RAM & I/O ports.
  • Many tasks can be performed, so the human effect can be reduced.
  • It is simple to use, troubleshooting & maintaining the system is simple.
  • It works like a microcomputer without any digital parts

Disadvantages of Microcontrollers Types

The disadvantages of the microcontrollers types include the following.

  • Programming Complexity
  • Electrostatic Sensitivity
  • Interfacing with high-power devices cannot possible.
  • Its structure is more complex as compared with microprocessors.
  • Generally, it is used in microdevices
  • It simply performs incomplete no. of executions simultaneously.
  • It is generally used in micro equipment
  • It has a more complex structure as compared to a microprocessor
  • The microcontroller cannot interface a higher power device directly
  • It only performed a limited number of executions simultaneously

Applications of Microcontrollers Types

Microcontrollers are mainly used for embedded devices, in contrast to the microprocessors which are utilized in personal computers otherwise other devices. These are mainly used in different appliances like implantable medical devices, power tools, engine control systems in automobiles, machines used in offices, appliances controlled through remote, toys, etc. The main applications of microcontrollers types include the following.

  • Automobiles
  • Hand-held metering systems
  • Mobile Phones
  • Computer Systems
  • Security Alarms
  • Appliances
  • Current meter
  • Cameras
  • Micro Oven
  • Measurement Instruments
  • Devices for process control
  • Used in metering & measurement devices, voltmeter, measuring rotating objects
  • Controlling Devices
  • Industrial instrumentation devices
  • Instrumentation devices in Industries
  • Light Sensing
  • Safety devices
  • Process control devices
  • Controlling devices
  • Fire detection
  • Temperature sensing
  • Mobile Phones
  • Auto Mobiles
  • Washing Machines
  • Cameras
  • Security Alarms

Thus, this is all about an overview of microcontrollers types. These Microcontrollers are single-chip microcomputers and the technology used for its fabrication is VLSI. These are also known as embedded controllers which are available in 4-bit, 8-bit,64-bit, and 128-bit. This chip is designed to control different embedded system functions. Here is a question for you, what is the difference between a microprocessor and a microcontroller?

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