History of MicrocontrollerThis was 1969, Business Computer Corporation (Busicom) famous calculator manufacturer of Japan, asked to Intel Corporation to develop few integrated circuits for them which were to be used in some specific calculators designed according to their projects. The company assigned the project to Marcian Edward "Ted" Hoff, Jr. who was one of the most efficient technical developer of Intel Corporation. After a long exercise on the project Hoff invented a different solutions for conventional IC design. His idea was that the operation of integrated circuit to be governed by the program stored in the IC itself. After a while he was able to develop first microprocessor. Then Federico Faggin had joined Intel as team leader of the Japany project of Busicom calculators. He had brought the concept of microprocessor to a ready-to-use product. It was about 275 days he took to develop final marketable product from original primary concept of microprocessor. The product was actually developed for Busicom hence Intel had to obtain a license for introducing microprocessor in open market. Biscom had given license to them without examining future market potential of that product. In 1971 Intel Corporation had got right to market this product. The first microprocessor IC launched in the market by Intel, was 4004 microprocessor chip. 4004 was 4-bit microprocessor with the speed of 6000 operations per second. In very next year (1972) Intel developed and introduced 8008 microprocessor with help of Texas Instruments. It was having 16Kb of memory, 45 instructions and capable of 300 000 operations per second. That was the first modern microprocessor and predecessor of all today’s microprocessors.

We are actually discussing about history of microprocessor instead of discussing about history of microcontroller the reason we will tell you letter anyway come to the point.

Motorola Inc. launched 8-bit microprocessor 6800 soon. The company also launched other peripherals like 6820 and 6850. Within very short period it was recognized by other competitor companies about future marker potential and importance in electronics technology of this product. Within 1974 manufacturing and marketing microprocessors becomes a major competition among the companies. They also started cutting down their price to capture maximum market share. In 1975, MOS Technology, Inc offered their selling price of 6501 and 6502 only $25 per piece. Both Motorola and Intel offered their microprocessors at the rate of $69.95 each. 6502 very soon becomes most popular 8-bit microprocessor with features like low price, 56 instructions and ability to address 64Kb directly. It was popularly used in computers by different computer manufacturing companies. Viewing this popularity of 6502, soon many companies like Rockwell, Sznertek, GTE, NCR, Ricoh etc started manufacturing and marketing 6502. Within 1982 per year sell of microprocessor became around 15 million.

Another great development of microprocessor technology was 8080 by Intel Corporation but it was costlier than others. But it had many additional features. In the mean time Federico Faggin had left Intel and started his won company Zilog Inc. He felt something to produce which would be compatible with the 8080. In the year of 1976 he brought into the market Z80 which was quite capable of performing all tasks of the 8080 with many additional features. Z80 is one of the most powerful microprocessors till date. It has capability of addressing 64Kb memory, has 176 instructions, a large number of registers, built-in refreshing option for dynamic RAM, single power supply, very high operating speed and many other features. Rapidly almost all 8080 based computers were converted to Z80. More rapidly it occupied the position of most popular, powerful and most commercially successful 8-bit microprocessor. Naturally, many new competitors comes into market for producing this same technology. For examples Mostek, NEC, SHARP and SGS etc.

In 1976 Intel Corporation had faced a huge loss of market share as they were not able to compete with z80 developed by Zilog Inc. founded by Federico Faggin former employee of Intel Corporation. In the

same year Intel introduced new upgraded version of 8-bit microprocessor named as 8085 but till they could not be able to regain their position as the Z80 was so better. Intel lost the battle. During this battle many other microprocessors came out in market such as 6809, 2650, SC/MP etc. but they could not be able to successfully dominate the market and died after some time. At last only 6502 and Z80 were able hold their market position and are popularly used till date.

Now we will tell you why we have discussed about history of microprocessor instead of discussing about history of microcontroller.

A microcontroller is not exactly a microprocessor actually a microprocessor differs from microcontroller in many aspects. Their functionality is different. The first and most important difference is its functionality. A microprocessor is computing machines. Microprocessors are not adjusted directly to the communicating to peripheral equipment.

For communicating with peripheral components, one microprocessor is required specialized circuits added as external chips. It is the heart of computer. From very beginning microprocessor remains same to till date.

(http://www.electrical4u.com/history-of-microprocessor-and-history-of-microcontroller/)

The first single chip microprocessor was the 4 bit Intel 4004 released in 1971, with other more capable processors available over the next several years. These, however all required external chips to implement a working system, raising total system cost, and making it impossible to economically computerize appliances.

The first computer system on a chip optimized for control applications - micro controller was the Intel 8048 released in 1976, with both RAM and ROM on the same chip. This chip would find its way into over one billion PC keyboards, and other numerous applications.

Most microcontrollers at this time had two variants. One had an erasable EEPROM program memory, which was significantly more expensive than the PROM variant which was only programmable once.

The Evolution of Microcontrollers has undergone a significant change since early 1970s. The Development table of microcontrollers is given as follows:

(http://www.zseries.in/embedded%20lab/8051%20microcontroller/history%20of%20microcontroller.php#.U5XQ-_mSwpo)

The first single-chip microprocessor was the 4-bit Intel 4004 released in 1971, with the Intel 8008 and

other more capable microprocessors becoming available over the next several years. However, both

processors required external chips to implement a working system, raising total system cost, and making

it impossible to economically computerize appliances.

The Smithsonian Institution says TI engineers Gary Boone and Michael Cochran succeeded in creating

the first microcontroller in 1971. The result of their work was the TMS 1000, which became commercially

available in 1974. It combined read-only memory, read/write memory, processor and clock on one chip

and was targeted at embedded systems.[1]

Partly in response to the existence of the single-chip TMS 1000,[2] Intel developed a computer system on

a chip optimized for control applications, the Intel 8048, with commercial parts first shipping in 1977.[2] It

combined RAM and ROM on the same chip. This chip would find its way into over one billion PC

keyboards, and other numerous applications. At that time Intel's President, Luke J. Valenter, stated that

the microcontroller was one of the most successful in the company's history, and expanded the division's

budget over 25%.

Most microcontrollers at this time had two variants. One had an erasable EPROM program memory, with

a transparent quartz window in the lid of the package to allow it to be erased by exposure

to ultraviolet light. The other was a PROM variant which was only programmable once; sometimes this

was signified with the designation OTP, standing for "one-time programmable". The PROM was actually

exactly the same type of memory as the EPROM, but because there was no way to expose it to ultraviolet

light, it could not be erased. The erasable versions required ceramic packages with quartz windows,

making them significantly more expensive than the OTP versions, which could be made in lower-cost

opaque plastic packages. For the erasable variants, quartz was required, instead of less expensive glass,

for its transparency to ultraviolet—glass is largely opaque to UV—but the main cost differentiator was the

ceramic package itself.

In 1993, the introduction of EEPROM memory allowed microcontrollers (beginning with the

Microchip PIC16x84)[citation needed] to be electrically erased quickly without an expensive package as required

for EPROM, allowing both rapid prototyping, and In System Programming. (EEPROM technology had

been available prior to this time, but the earlier EEPROM was more expensive and less durable, making it

unsuitable for low-cost mass-produced microcontrollers.) The same year, Atmel introduced the first

microcontroller using Flash memory, a special type of EEPROM.[3] Other companies rapidly followed suit,

with both memory types.

Cost has plummeted over time, with the cheapest 8-bit microcontrollers being available for under 0.25

USD in quantity (thousands) in 2009,[citation needed] and some 32-bit microcontrollers around 1 USD for similar

quantities.

Nowadays microcontrollers are cheap and readily available for hobbyists, with large online communities

around certain processors.

In the future, MRAM could potentially be used in microcontrollers as it has infinite endurance and its

incremental semiconductor wafer process cost is relatively low.

(http://en.wikipedia.org/wiki/Microcontroller#History)

The First Microcontroller

In 1971, the first microcontroller was invented by two engineers at Texas Instruments, according to the Smithsonian Institution. Gary Boone and Michael Cochran created the TMS 1000, which was a 4-bit microcontroller with built-in ROM and RAM. The microcontroller was used internally at TI in its calculator products from 1972 until 1974, and was refined over the years. In 1974, TI offered the TMS 1000 for sale to the electronics industry. The TMS 1000 was available in various configurations of RAM and ROM sizes. As of 1983, about 100 million TMS 1000 devices had been sold.

Intel Microcontrollers

In addition to producing the first microprocessor, Intel also developed many important microcontrollers, two of which are the 8048 and 8051. Introduced in 1976, the 8048 was one of Intel's first microcontrollers and was used as the processor in the IBM personal computer keyboard. It is estimated that over one billion 8048 devices were sold. The 8051 followed in 1980 and became one of the most popular microcontroller families. Variations of the 8051 architecture are still being produced today, making the 8051 one of the most long-lived electronic designs in history.

Electrically Erasable Memories

During the 1990s, microcontrollers with electrically erasable and programmable ROM (EEPROM) memories, such as flash memory, became available. These microcontrollers could be programmed, erased and reprogrammed using only electrical signals. Prior to the electrically reprogrammable devices, microcontrollers often required specialized programming and erasing hardware, which required that the

device be removed from its circuit, slowing software development and making the effort more expensive. With this limitation removed, microcontrollers were able to be programmed and reprogrammed while in a circuit so devices with microcontrollers could be upgraded with new software without having to be returned to the manufacturer. Many current microcontrollers, such as those available from Microchip and Atmel, incorporate flash memory technology.

Modern Microcontrollers

In addition to general purpose devices, specialized microcontrollers are being produced for areas such as automotive, lighting, communications and low-power consumer devices. Microcontrollers have also become smaller and more powerful. For example, in 2010, Atmel announced a flash microcontroller in a package measuring 2 mm by 2 mm. These tiny microcontrollers are small enough and cheap enough to be used in products such as toys and toothbrushes.(http://www.ehow.com/info_10018768_history-microcontroller.html#ixzz34JCiNy3x)

The first microprocessors came from the early 1970s. They originally were used in electronic calculators, an invention most of us can't envision not having anymore. When they became more affordable, people started using them for automation of mundane tasks, communication devices, and much more.

The first microprocessor was the Intel 4004. It cost thousands of dollars to design, and the project began in 1969. Intel was asked by a company called Busicom to design this programmable chip for their calculators.

A few years down the road in 1972, Intel released the 8008. This was the first 8 bit microprocessor. Shortly after, Zilog came out with the Z80 in 1976 which can be found in many products today ranging from TI graphing calculators (TI-86) to Nintendo's gameboy color. Also, Motorola came out with a competing product, the M6800 in 1974.

Fastforward to 1979, and Motorola released the MC68000, commonly known as the 68K. This was a 32 bit design that is still used today in devices such as the TI-89 calculator.

General Instruments developed the 8-bit PIC in 1975. In 1985 General Instruments restructured their business and PIC development was pretty much scrapped. Shortly after in 1989 Microchip Technology Inc. formed and rebuilt the PIC with EPROM memory allowing the program written to the chip to be re-written instead of one time use. However; it was still very costly to invest in the hardware to program and re-program these chips. It wasn't until 1993 when EEPROM memory was introduced allowing it to be erased electronically. Also, in 1993 the PIC16C84 featured a serial programming interface that allowed hobbyists to program it via the serial port on their personal computer. As such, the PIC microcontroller is still very popular among hobbyists and professionals.

(http://php.scripts.psu.edu/sbl5007/microcontrollers.php)

Basics of MicrocontrollersIn this article we will be discussing an important aspect of electronic systems. Many of us use CD/DVD players, TVs, cellphones, microwave ovens, etc. Have your thought of the electronics behind these systems. All of them have one thing in common. A microcontroller. An electrical engineer needs to know about basics of microcontrollers as all of the consumer electronic products use microcontrollers.

So, let’s come to the topic. What is a microcontroller?

Most of you would have heard of a processor or a microprocessor used in computers. For eg. Intel core processors, Pentium, etc. Microprocessors are basically used to process data. It accepts data in digital form, processes it according to the user’s instruction and gives an output. Many people think that microcontroller and microprocessor represent the same thing. However, both are completely different. To illustrate what a microcontroller is let us take the example of a computer. Most of you may be reading this article on your computer. Does your computer only contain a microprocessor? No. It contains many other things. It has external memory components like RAM, ROM, a hard disk drive, etc. What’s so amazing about a microcontroller? It contains a CPU and the additional memory components. You don’t need to add these extra components as in the case of a microprocessor. In simple words, a microcontroller is a single chip computer. But there is a compromise on the performance of CPU and memory in the case of a microcontroller.

To understand the basics of microcontroller let’s discuss the components in it:

Central Processing Unit (CPU):It acts as the brain of the microcontroller. It is used to process data as instructed by the use. The main functions include arithmetic operations like addition, subtraction, multiplication, division, etc. and also for copying or moving data from one address to another.

Microcontroller

ROM or Read Only Memory:ROM is used to store the user instructions or program code. Every time the microcontroller is powered the instructions in the ROM is executed. This type of memory is non-volatile i.e. the contents of the memory are retained even if the power is lost. There are many types of ROMs. They are:-

i) EPROM (Erasable Programmable Read Only Memory):- This type of ROM can be erased and programmed again. UV(Ultraviolet)rays are used to erase this kind of memory.This type of ROM is mostly not because costly equipment is needed to reprogram the memory.

ii) EEPROM(Electrically erasable Programmable Read Only Memory):- It is similar to EPROM but the memory can be erased electrically without the use of UV rays. One disadvantage is that it takes a large amount of time to reprogram this kind of memory.

iii) FLASH:- It is similar to EEPROM but it is faster than EEPROM. But it has a smaller lifetime compared to EEPROM.

3) RAM(Random Access Memory):- This memory is used during the execution of program. It is for storing variables and other program data.

4) I/O PORTS:- These ports are used to receive data from the external environment or the user and also to send data. There are two types of I/O ports:-

i) Digital:-These ports are used to send or receive digital data. Digital means discrete data i.e 0V or 5V.

ii) Analog:- Since most of the sensors give analog data analog input pins are commonly used to read sensor data. You can also write analog voltage values to these ports.

The number of analog and digital ports depend on the microcontroller.

5) Timers :- Timers are used to keep track of the time that has passed. Timers are extremely useful in many cases where outputs are to be maintained for a sufficient amount of time.

These are some of the basic components present in a microcontroller. Microcontrollers also contain ADCs ( Analog to Digital Converters ), DAC ( Digital to Analog Converters ) and many other peripherals.

So, is that it? Can the microcontroller be used just like that? Give it a power supply and will it start working? No. It needs instructions on how to operate in a particular situation. These instructions form the software. The user writes the software according to his needs. Previously, assembly language was used for microcontroller programming. This was tedious and took a lot of time. But these days it is a lot more easier due to higher level languages like c. Most companies manufacturing microcontrollers also provide compilers for compiling the c code that you write. Microchip provides MPLAB IDE(Integrated Development Environment) for developing applications with its microcontrollers. You can write your code, generate a hex file and burn it into your microcontroller and it is ready for use.

Simple, isn’t it? Let me just give you a small example of a working application for better understanding basics of microcontroller. Most of you would have gone in lifts. The lift door automatically opens if a person is about to enter while it is closing. You would have also noticed automatic opening of glass doors

in various stores. These applications can be easily developed with PIR sensors and microcontrollers. Most PIR sensors give an output of 5V a person is near it and 0V if there is no object near it. The PIR sensor can be connected to one of the digital pins of the microcontroller and the microcontroller can be programmed in such a way that the actuating unit ( motors attached to the door ) rotates in a particular direction the digital pin receives a 5v(a person is standing near it) and in another direction if the digital pin receives a 0V. There are a lot of other factors to be considered if you are going to develop a real world application and you also need separate circuitry for driving the motors but this is just to give a simple idea of most basics of microcontrollers and how these systems work.

There are a lot of applications that you can think of and implement using a microcontroller. In addition to this you can also attach a LCD display and various other types of displays to display data. The main advantage of microcontroller based systems is that microcontrollers are cheap and a working prototype can be easily built. A lot of companies are manufacturing microcontrollers. Some companies include Microchip, Atmel, Texas Instruments.(http://www.electrical4u.com/basics-of-microcontrollers/)