What is a Microcontroller?

Microcontroller is a device which integrates a number of the components of a microprocessor system onto a single microchip and optimised to interact with the outside world through on-board interfaces; i.e. it is a little gadget that houses a microprocessor, ROM (Read Only Memory), RAM (Random Access Memory), I/O (Input Output functions), and various other specialized circuits all in one package.

On the other hand, a microprocessor is normally optimised to co-ordinate the flow of information between separate memory and peripheral devices which are located outside itself. Connections to a microprocessor include address, control and data busses that allow it to select one of its peripherals and send to or retrieve data from it. Because a microcontrollers processor and peripherals are built on the same silicon, the devices are self-contained and rarely have any bus structures extending outside their packages.

So a microcontroller incorporates onto the same microchip the following:

* The CPU core

* Memory (both ROM and RAM)

* Some parallel digital I/O

What is an Embedded system ?

An embedded system is a computer system designed to do one or a few dedicated and/or specific functions often with real-time computing constraints. It is embedded as part of a complete device often including hardware and mechanical parts. By contrast, a general-purpose computer, such as a personal computer (PC), is designed to be flexible and to meet a wide range of end-user needs. Embedded systems control many devices in common use today.

Embedded systems are controlled by one or more main processing cores that are typically either microcontrollers or digital signal processors (DSP). The key characteristic, however, is being dedicated to handle a particular task. They may require very powerful processors and extensive communication, for example air traffic control systems may usefully be viewed as embedded, even though they involve mainframe computers and dedicated regional and national networks between airports and radar sites (each radar probably includes one or more embedded systems of its own).

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