Wednesday, July 22, 2009

Basics of Microcontrollers (Part 1)

In this section of my blog, the most fundamental aspects of microcontrollers will be discussed. This includes the definitions of a microcontroller and the relevant terms, types of microcontrollers, and microcontroller programming. Enjoy!

What is a Microcontroller?

A microcontroller is a complete computer system on an integrated chip, typically combining a Central Processing Unit (CPU), memory units (RAM, ROM), and I/O ports so that they can function as a tiny, dedicated computer. The input ports are used to detect action by a user or read input from attached sensors (e.g., light, heat, motion sensors), whereas the output ports are to display the results (on LEDs, LCD Display, Monitor, etc) of processing based on the inputs, or to take any actions (like switching on/off devices, send messages to remote stations, etc). In the physical sense, the I/O port relates to metal pins on the part package that are used to connect to other circuitry in the system. Microcontrollers usually have just a few I/O pins, as few as 8 or as many as 100.

Microcontrollers are everywhere.

Microcontrollers have become common in many areas, and can be found hidden in many categories of products like home appliances, computer equipments, automobiles, etc.
A microwave oven with a LCD screen and a keypad contains a microcontroller. Microcontrollers are used in running the traffic light at an intersection. In automobiles, the engine, the anti-lock brakes, the cruise control, and so on, are all controlled by microcontrollers these days. From the simplest gadgets, like digital cameras, cell phones, printing machines etc, to highly sophisticated satellite and rocket missile systems, the microcontrollers have become ubiquitous.

How does a microcontroller look?

Figure 1(a). PIC16F628 microcontroller

Figure 1(b). Pin description of PIC16F628

Figure 1(a) above shows a 18 pin microcontroller named PIC16F628, manufactured by Microchip company. The metal pins are Input/Output and power supply pins. The description of the various pins of PIC16F628 is shown in Figure 1(b). You don't have to understand the detail functions of these pins at this point. Just move ahead.

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