INTRODUCTION TO MICROCONTROLLER

Before we Start writing embedded codes we want to urged interesting individual to have a background knowledge on microcontrollers ,compilers , c language and the programmer .

What is a Microcontroller

A microcontroller (or MCU for microcontroller unit is a small computer on a single integrated circuit. In modern terminology, it is a system on a chip or SoC. A microcontroller contains one or more CPUs (processor cores) along with memory and programmable input/output peripherals.

Novices in electronics usually think that the microcontroller is the same as the microprocessor.

That’s not true. They differ from each other in many ways. The first and most important difference in favour of the microcontroller is its functionality. In order that the microprocessor may be used, other components, memory comes first, must be added to it. Even though it is considered a powerful computing machine, it is not adjusted to communicating to peripheral environment. In order to enable the microprocessor to communicate with peripheral environment, special circuits must be used. This is how it was in the beginning and remains the same today.

A microcontroller contains some of the following peripheral components:

•Memory

•Timers, including event counting, input capture, output compare, real-time interrupt,

and watchdog timer

•Pulse-width modulation (PWM)

•Analog-to-digital converter (ADC)

• Digital-to-analog converter (DAC)

• Asynchronous serial communication interface (UART)

• Synchronous serial communication interfaces (SPI, I2C, and CAN)

• Direct memory access (DMA) controller

• Memory component interface circuitry

• Software debug support hardware etc.

The discussion of the functions and applications of these components is the subject of this text. Most of these functions are discussed in details in later chapters. Since their introduction, MCUs have been used in almost every application that requires certain amount of intelligence. They are used as controllers for displays, printers, keyboards, modems, charge card phones, palm-top computers, and home appliances, such as refrigerators, washing machines, and microwave ovens. They are also used to control the operation of engines and machines in factories. One of the most important applications of MCUs is probably the automobile control. Today, a luxurious car may use more than 100 MCUs. Today, most homes have one or more MCU-controlled consumer electronics appliances. In these applications, people care about only the functionality of the end product rather than the MCUs being used to perform the control function. Products of this nature are often called embedded systems.

Difference between a Microprocessor and Microcontroller

A Microprocessor which is the heart of these devices needs a host of external devices to make it communicate with real-world. That means for a complete system would need a system to read the inputs or data from keyboard, after processing the result should write outputs to a terminal, need to store intermediate processing data into some memory, and finally it should need a place where to keep permanent information into some safe place.

To make the successful system all those additional devices which are independent circuits, work in harmony with the Microprocessor, to make one system. This makes the system more flexible that means you can add more memory, change capacity of hard drives, add or remove CD-ROMs, sound cards etc and also the cost of maintenance is reduced like for a memory storage problem you just need to change the memory unit not the total system.

A microcontroller on the other hand is made up of most of these devices built exactly within the same package. Your microcontroller will therefore contain, the Microprocessor, RAM, ROM, Timers, I/O etc. all packed within one integrated circuit. This facilitates the development process, as well as reduce the requirements of external components, however this also means you cannot change, the number and type of integrated devices. The applications where a microcontroller will be used, vary. They are usually quite simple, and do not require as much processing power as a Microprocessor system needs, so the microcontrollers with varying amounts of RAM, ROM, I/O lines and timers etc have been made available. Essentially all are almost same, and they only vary in the number of resources available on them. So for a particular application you chose a microcontroller, not the one which has maximum resources, but the one which has just enough to do the job.

Thus a microcontroller is a complete, small scale computer with all the necessary devices on-board. All you need is the external hardware, which you want to drive, like sensors and motors etc.