Embedded system can be classified into various categories based on their performance, Functional Requirement and Performance of Microcontroller.

Embedded system can be classified into 4 categories based on performance :

1. Real Time: It is defined as a system that gives a required o/p in a particular time. These type of system follows deadline for completion of tasks. They are classified as soft and hard real time systems.

2. Stand Alone: It doesn't require a host system like computer it works by itself. It takes input from input port either analog or digital and processes, calculates and converts data and gives result via connected devices.

Fig. 1.4 Classification of Embedded systems

3. Networked : These types of Embedded systems are related to a network to access the resources. The connected network can be LAN, WAN or the internet. The connection can be either wired or wireless. This type of embedded system is the fastest growing area in all the embedded system application. The embedded web server is a type of system wherein all the embedded devices are connected to a web server and accessed and controlled by a web browser. Example for LAN network embedded system is a home security system wherein all systems are connected and run on the protocol TCP/IP.

4. Mobile : They are used in portable embedded devices like cellphones, mobiles, digital cameras MP3 players and personal digital assistants, etc. The basic limitation of this device is the other resources and limitation of memory.

Embedded system can be classified into 3 categories based on performance of Microcontroller :

1. Small Scale : Systems that are designed using 8~blt microcontrollers like 8051 or 16-bit microcontrollers like 80196 fall under this category of embedded systems i.e. small scale embedded systems. The hardware and software complexities in these systems is very low. The power consumption is also not an issue and they are mostly battery operated. The coding can be done in simple embedded 'C'. Also the memory may be small and hence care has to be taken that the software It not very huge. An example of such a system could be a simple temperature measurement embedded system, a robotic arm controller, etc.

2. Medium Scale : Systems that are designed using 16-bit to 32-bit microcontrollers fall under this category. They may also have multiple such microcontrollers or DSPs. The hardware as well as software complexity of such systems is very high. They mostly have an operating system besides the applications required. The RTOS (Real Time Operating System) is used in such systems. These systems may also employ some ASSP processors to implement: special task if any. Various examples of medium scale embedded systems are routers for networking, ATM (is. Automated Teller Machine for bank transactional machines etc.

3. Sophisticated : These systems also have high end microcontrollers. The hardware and software complexes are also very high. The design tools required are also complicated and costly. The systems also use the RTOS and complicated time bound applications. The time bounding on the computations is a big task in such systems. These systems are used for cutting edge applications like smart phones, multimedia systems etc.