In order to introduce embedded systems and RTOS in the simplest terms possible, this content gives you a foundational learning experience with some real-world examples that will aid in your understanding.
System : System is a method of carrying out several tasks according to a precise plan and procedure.
Embedded system :
An embedded system is a full hardware and software setup designed to carry out a particular purpose.
It need to be a stand-alone system or a component of a sizable system.
Three main component
- Hardware – A set of electronics components required to build an system which able to perform task.
- Software – This part provide flexibility to the system to perform different task in order to get more outputs.
- RTOS – Real time operating system which help to operate system in real time with no unwanted delay in it.
Characteristics of embedded system
Single functioned – The system performs a specific single task in a repeatable manner (only one task)
Tightly constrained –
- Should have low in cost
- Size should be smaller to fit easily in equipment.
- Expected performance should be fast.
- Low in power consumption
Real time operations
Unwanted and additional delays must be excluded. Real-time performance is required by real time operations.
Microprocessor and microcontroller board
A processor that is application dependent will have to be used, which will only deal with certain tasks that are related to the application.
Embedded system processors
Processors inside a system :
- CU – Control unit
- EU- Execution unit
Control unit – There is a control unit which is responsible for managing and controlling the flow and execution of the program.
Execution unit – All performed tasks of control unit is being executed by this execution unit.
Types of Processors :
- Application specific system processors – which performs specific task embedded into it.
- Application specific instruction processors – It performs specific set of instructions to execute program
- General purpose processor – Which is used widely in form of microprocessors and microcontrollers which can perform specific as well multiple task at the same time.
Categories of embedded system
1- Stand alone embedded system
Stand alone embedded system used commonly in home appliances like TV, fridge, washing machine etc where we gave input in form of electric signals by wireless remotes or mechanical buttons and get desired of specific task.
2- Real time system
To complete given specific task in some fix time interval or no delay allowed in it . So it should be process input data and give output in real time without any delay .
3- Hard real time system
Hard real-time systems have strict deadlines, and if those deadlines are missed, a system failure will result. Even if a deadline is missed in soft real-time systems, the system will continue to function, but output quality will be lower than in real-time systems.
For example in car air bag system when unexpected accident occurs then airbag have to open in milliseconds otherwise it causes life loss situation . So hard real time system have to work without failure and without any delay.
3- Soft real time system
If results are not produced in accordance with the required timing, a system is said to be operating in soft real-time. While it is not necessary for every task in a soft real-time system to fulfil its deadline, it should still be processed and produce a result.
For example while changing your tv channel if there will be some delay introduced then it will be acceptable it doesn’t cause any life loss situation , so this type of system have to work in real time but if some how any extra delay occurred during processing or output then it should not a big issue.
3- Networked information appliances
Networked embedded systems rely on communication with web servers across wired or wireless networks to provide output. Security systems for the home and workplace are frequent instances of network embedded systems.
4- Mobile devices embedded system
An embedded system which perform small task and easily movable from one place to another. example wireless car key or simple mobile phones.