A microcontroller is
a small and low-cost computer built for the purpose of dealing with specific
tasks, such as displaying information in a microwave LED or receiving information from a television’s remote control. Microcontrollers are
mainly used in products that require a degree of control to be exerted by the
user.
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 advantage: The biggest advantage of microcontrollers against larger microprocessors is that the design and hardware costs are much lesser and can be kept to a minimum. A microcontroller is cheap to replace, while microprocessors are ten times more expensive.
· Lesser power usage: Microcontrollers are generally built using a technology known as Complementary Metal Oxide Semiconductor (CMOS). This technology is a competent fabrication system that uses less power and is more immune to power spikes than other techniques.
· All-in-one: A microcontroller usually comprises 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.
The term microprocessor and microcontroller have always been confused with each other. Both of them have been designed for real time application. They share many common features and at the same time they have significant differences. Both the IC’s i.e., the microprocessor and microcontroller cannot be distinguished by looking at them. They are available in different version starting from 6 pin to as high as 80 to 100 pins or even higher depending on the features.
Difference between microprocessor and microcontroller
Microprocessor is an IC which has only the CPU inside them i.e. only the processing powers such as Intel’s Pentium 1,2,3,4, core 2 duo, i3, i5 etc. These microprocessors don’t have RAM, ROM, and other peripheral on the chip. A system designer has to add them externally to make them functional. Application of microprocessor includes Desktop PC’s, Laptops, notepads etc.
But this is not the case with Microcontrollers. Microcontroller has a CPU, in addition with a fixed amount of RAM, ROM and other peripherals all embedded on a single chip. At times it is also termed as a mini computer or a computer on a single chip. Today different manufacturers produce microcontrollers with a wide range of features available in different versions. Some manufacturers are ATMEL, Microchip, TI, Freescale, Philips, Motorola etc.
Microcontrollers are designed to perform specific tasks. Specific means applications where the relationship of input and output is defined. Depending on the input, some processing needs to be done and output is delivered. For example, keyboards, mouse, washing machine, digicam, pendrive, remote, microwave, cars, bikes, telephone, mobiles, watches, etc. Since the applications are very specific, they need small resources like RAM, ROM, I/O ports etc and hence can be embedded on a single chip. This in turn reduces the size and the cost.
Microprocessor find applications where tasks are unspecific like developing software, games, websites, photo editing, creating documents etc. In such cases the relationship between input and output is not defined. They need high amount of resources like RAM, ROM, I/O ports etc.
The clock speed of the Microprocessor is quite high as compared to the microcontroller. Whereas the microcontrollers operate from a few MHz to 30 to 50 MHz, today’s microprocessor operate above 1GHz as they perform complex tasks.
Comparing microcontroller and microprocessor in terms of cost is not justified. Undoubtedly a microcontroller is far cheaper than a microprocessor. However microcontroller cannot be used in place of microprocessor and using a microprocessor is not advised in place of a microcontroller as it makes the application quite costly. Microprocessor cannot be used stand alone. They need other peripherals like RAM, ROM, buffer, I/O ports etc and hence a system designed around a microprocessor is quite costly.
How does a 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.
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.
Features of microcontrollers
1. Architectural features:
Most microcontrollers built today are based on the CISC (Complex
Instruction Set Computer) platform. A typical CISC microcontroller has
over 80 instructions and it is quite common for the instructions to all behave
quite differently.
The main advantage of CISC architecture is that the instructions are
macro-like, allowing the programmer to use one instruction in place of many
simpler instructions.
2. Advanced Memory features:
a. Electrically Erasable Programmable Read Only
Memory (EEPROM):
Many microcontrollers use the economic EEPROM for smaller amount of
memory that have frequently changeable data. This type of memory is relatively
slow, and the number of erase/write cycles allowed in its lifetime is
limited.
b. FLASH (EPROM):
Flash provides microcontrollers with a better solution than EEPROM for
requirements of large amounts in non-volatile program memory. EPROM is faster
and permits more erase/write cycles than EEPROM.
3. Power Management features
A majority of microcontrollers usually support an operation of 3 - 5.5 V.
As consumer goods become trendier, compact and lighter, the focus is on
microcontrollers to ensure that products with less power usage are efficiently
built and then used by end-users.
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.
History and Key Developments
In 1975, Intel fabricated a chip (Intel 8048) with inbuilt RAM and ROM
which was widely used in numerous applications. The microcontrollers had two
variants namely EPROM which was erasable but expensive and PROM which could be
programmed only once. In 1993, EEPROM memory was introduced in the
microcontrollers which electrically erasable and at affordable price. Atmel
used the Flash memory and launched the first microcontroller. After this, many
companies fabricated microcontrollers with both type of memory.
The microcontroller became popular after Intel Corporation released an
8-bit version in 1981 called the 8051. Intel allowed other manufacturers to
make alternate versions of the 8051, and this ensured that numerous versions of
the 8051 entered the market. Some of these controllers had different speeds
with multiple ROMs mounted on a single chip.
The family of 8051 microcontrollers signalled an electronic revolution
with the end user reaping the benefits in technology and science.
As years passed by, microcontrollers have grown to offer much more to
end-users and businesses. Some of the key developments in the microcontroller
lifecycle are as follows:
1. More ease-of-use and ability to reach market faster.
2. More energy efficiency.
3. More integrated features like RF and USB.
4. Smaller form factors.
5. Increasing processing power.
In future, MRAM (Magnetoresistive Random Access Memory) could be used in
microcontrollers as it can store large amount of data which allows it to access
faster consuming less power of battery.
Comparative study of different families:
8051, AVR/ATmega, PIC
8051: These
microcontrollers are old but still trendy and most of the companies fabricate
these microcontrollers. The older types of 8051 have 12 clocks per instruction
that make it sluggish whereas the recent 8051 have 6 clocks per instruction.
The 8051 microcontroller does not have an in built memory bus and A/D
converters. In 1980, Intel fabricated the single chip microcontroller 8051 with
Harvard architecture.
PIC: Programmable Interface Controller is usually referred as PIC. They
are slightly older than 8051 microcontrollers but excel cause of their small
low pin count devices. They perform well and are affordable. The
Microchip technology fabricated the single chip microcontroller PIC with
Harvard architecture. The programming part is very tedious and hence it is not
recommended for beginners.
AVR: In 1996, Atmel
fabricated this single chip microcontroller with a modified Harvard
Architecture. This chip is loaded with C- compiler, Free IDE and many more
features. This microcontroller is a bit difficult for the starters to
handle.
Criteria for choosing a microcontroller
The most important factor is that the microcontroller should be
cost-efficient and work capably to handle the dedicated task. Some questions
that should be asked while deciding on a microcontroller are as
follows:
1. What is the maximum speed of the microcontroller?
2. What is the amount of RAM and ROM on chip?
3. How easy it is to upgrade to higher upgrade or lower consumption
versions?
4. Is the microcontroller readily available at cheaper rates?
5. What is the number of I/O pins and timer on the chip?
Future of microcontrollers
and applications
The future is bright and shining for microcontroller manufacturers. This
is because the global economies are booming and microcontrollers have a role to
play in almost every gadget present on earth. The list of applications for
these microcontrollers is:
1. Energy Management:
Technology for energy management is in great demand due to government
initiatives that focus on energy. Efficient metering systems help in
controlling energy usage in homes and industrial applications. These metering
systems are made capable by incorporating microcontrollers.
2. Touch screens:
A touch screen is accepted as the most efficient method to implement user
control. They enable dynamic user interfaces and allow increased productivity.
Touch screen controller implementation is microcontroller-based and therefore,
ample opportunities lie ahead for microcontroller providers that incorporate
touch-sensing capabilities in their designs. Portable electronics such as home
appliances, cell phones, media players, gaming devices are some of the domains
where microcontroller-based touch screens will be in demand.
3. Automobiles:
Microcontrollers find wide usage in hybrid vehicles, especially to ensure
smooth and simultaneous functioning of electric and petrol engines.
Additionally, almost every car manufacturer uses microcontrollers to control
functions within their vehicles and to ensure error-free rides for their
customers.
4. LED Lighting:
Microcontrollers are used for led lighting in residential and
industrial locations to enable greater control and power savings.
5. Personal Medical Devices:
The rise and popularity of portable medical devices such as blood
pressure and glucose monitors have ensured that microcontrollers will have a
role in the medical industry. Microcontrollers are used to display date and
increase reliability in providing medical results.
Finally:-
Microcontrollers are a very important electronic material now a day. But in our
country,ETHIOPIA, this is not still in use in a wider area. universities and
colleges have to deal with it and the course should have to be given as a
carriculum specially in electrical and computer engineering department in all
streams. Specifically for Communication, Control And computer streams.
IN THIS BLOG I WILL DEAL
ABOUT THESE MICROCONTROLLERS AND THIER APPLICATIONS IN DETAIL AND REAL WORLD
WORKS REGARDING IT.
ENJOY
