Categories of Embedded System

Categories of Embedded System


Stand-alone embedded systems:


A stand-alone embedded system is like an isolated node, which takes inputs and produces output. The inputs can be electrical signals form sensors, or commands from human beings, like push key buttons or dip switches. The output can be electrical signals to drive devices such as LCDs and LEDs or motors etc. This type of embedded systems is found in industries for process control systems and as well as in household items and toys.

Eg. An air-condition unit can be set to run, when a particular temperature is reached.

Real-time embedded systems

The embedded systems which are bound by strict deadlines are called as embedded system. Or a system which process or respond with a certain time frame to it inputs.

Eg. Mission control systems such as in cars, aircrafts etc.

The real time embedded systems can be classified to 3 categories.

Hard real time systems:

These are embedded systems which will have catastrophic disaster, if a deadline is mixed. The penalty of missing the deadline is greater than the reward for achieving the deadline. This type of system is strictly time bound.
Eg. Engine control parts of aircrafts and automotives.

Firm real time systems:

The embedded systems in which a slight degradation in the real-time constraints are accepted. The penalty for missing the deadline is equal to the reward for achieving the deadline.

Soft real time systems:

The systems in which real-time constraints are present but not critical. The penality for missing the deadline is less than the reward for achieving the deadline.


Networked embedded systems :

The embedded systems which are connected to a network – based on protocols like TCP/IP, CAN, LIN, MOST etc. A best example of networked embedded system is a networked camera sending signals over the TCP/IP protocol. This type of embedded systems are present in industries, where data have to be collected from various nodes, like from pressure sensor, temperature sensor, speed sensor, humidity sensor, light sensor, rpm sensor etc.


Mobile Devices :

With the advent of wireless networks that can support very high speeds, mobile devices are capable of supporting high data rates in addition to the voice services. Accessing internet services such as e-mail, WWW, and so on can be done while a person is on move. Such type of embedded systems requires a powerful operating system and powerful processor which can do powerful mathematical computations with less amount of battery power.

The main requirements of these mobile devices are threefold – they should have powerful computing and communication capabilities, they should be able to perform some real time tasks in addition to some non- real time tasks, and they should be capable of handling multimedia applications. These requirements call for powerful processor, a powerful operating system, and a lot of memory with minimal power consumption.