Introduction to Microservice Architecture Using SpringBoot - Part 1

1. What is an embedded system? What are the components of embedded system?

An embedded system is a combination of computer hardware and software designed for a specific function. Embedded systems may also function within a larger system. The systems can be programmable or have a fixed functionality. Industrial machines, consumer electronics, agricultural and processing industry devices, automobiles, medical equipment, cameras, digital watches, household appliances, aeroplanes, vending machines and toys, as well as mobile devices, are possible locations for an embedded system.
The three main components of an embedded system are:
1. Hardware
2. Main application software
3. RTOS

2. What are the characteristics of embedded systems.

1. Single-functioned - An embedded system usually performs a specialized operation and does the same repeatedly. For example, A pager always functions as a pager.

2. Tightly constrained - All computing systems have constraints on design metrics, but those on an embedded system can be especially tight. Design metrics is a measure of an implementation's features such as its cost, size, power, and performance. It must be of a size to fit on a single chip, must perform fast enough to process data in real-time and consume minimum power to extend battery life.

3. Reactive and Real-time - Many embedded systems must continually react to changes in the system's environment and must compute certain results in real- time without any delay. Consider an example of a car cruise controller; it continually monitors and reacts to speed and brake sensors. It must compute acceleration or de-accelerations repeatedly within a limited time; a delayed computation can result in failure to control of the car.

4. Microprocessors based - It must be microprocessor or microcontroller based.

5. Memory-It must have a memory, as its software usually embeds in ROM. It does not need any secondary memories in the computer.

3. Explain the basic Structure of an Embedded System.

1. Sensor - It measures the physical quantity and converts it to an electrical signal which can be read by an observer or by any electronic instrument like an A2D converter. A sensor stores the measured quantity to the memory.

2. A-D Converter - An analog-to-digital converter converts the analog signal sent by the sensor into a digital signal.

3. Processor & ASICS - Processors process the data to measure the output and store it to the memory.

4. D-A Converter - A digital-to-analog converter converts the digital data fed by the processor to analog data

5. Actuator - An actuator compares the output given by the D-A Converter to the actual (expected) output. stored in it and stores the approved output.

4. What do you mean by Processors in a System.

A processor has two essential units -

1. Program Flow Control Unit (CU)
2. Execution Unit (EU)

The CU includes a fetch unit for fetching instructions from the memory. The EU has circuits that implement the Instructions pertaining to data transfer operation and data conversion from one form to another.

The EU includes the Arithmetic and logical Unit (ALU) and also the circuits that execute instructions for a program control task such as interrupt, or jump to another set of instructions. A processor runs the cycles of fetch and executes the instructions in the same sequence as they are fetchedfrom memory.

Processors can be of the following categories -

• General Purpose Processor (GPP)

1. Microprocessor
2. Microcontroller
3. Embedded Processor
4. Digital Signal Processor
5. Media Processor

• Application Specific System Processor (ASSP)
• Application Specific Instruction Processors(ASIPs) 
• GPP core(s) or ASIP core(s) on either an Application Specific Integrated Circuit (ASIC) or a Very Large Scale Integration (VLSI) circuit.

5. How does an embedded system work?

The processor may be a microprocessor or microcontroller. Microcontrollers are simply microprocessors with peripheral interfaces and integrated memory included. Microprocessors use separate integrated circuits for memory and peripherals instead of including them on the chip. Both can be used, but microprocessors typically require more support circuitry than microcontrollers because there is less integrated into the microprocessor. The term system on a chip (SoC) is often used. SoCs include multiple processors and interfaces on a single chip. They are often used for high-volume embedded systems. Some example SoC types are the application- specific integrated circuit (ASIC) and the field- programmable gate array (FPGA).

Often, embedded systems are used in real-time operating environments and use a real-time operating system (RTOS) to communicate with the hardware. Near-real-time approaches are suitable at higher levels of chip capability, defined by designers who have increasingly decided the systems are generally fast enough and the tasks tolerant of slight variations in reaction. In these instances, stripped-down versions of the Linux operating system are commonly deployed, although other OSes have been pared down to run on embedded systems, including Embedded Java and Windows loT (formerly Windows Embedded).

6. What is an Embedded System Design?

A system designed with the embedding of hardware and software together for a specific function with a larger area is embedded system design. Steps in the Embedded System Design Process:

The different steps in the embedded system design flow/flow diagram include the following.

1. Abstraction: In this stage the problem related to the system is abstracted.

2. Hardware Software Architecture: Proper knowledge of hardware and software to be known before starting any design process.

3. Extra Functional Properties: Extra functions to be implemented are to be understood completely from the main design.

4. System-Related Family of Design: When designing a system, one should refer to a previous system-related family of design.

5. Modular Design: Separate module designs must be made so that they can be used later on when required.

6. Mapping: Based on software mapping is done. For example, data flow and program flow are mapped into one.

7. User Interface Design: In user interface design it depends on user requirements, environment analysis and function of the system. For example, on a mobile phone if we want to reduce the power consumption of mobile phones we take care of other parameters, so that power consumption can be reduced.

8. Refinement: Every component and module must be refined appropriately so that the software team can understand. Architectural description language is used to describe the software design.

1. Control Hierarchy
2. Partition of structure
3. Data structure and hierarchy
4. Software Procedure

7. Challenges in Embedded System Design.

A system designed with the embedding of hardware and software together for a specific function with a larger area is embedded system design. In embedded system design, a microcontroller plays a vital role. Micro-controller is based on Harvard architecture, it is an important component of an embedded system. External processor, internal memory and i/o components are interfaced with the microcontroller. It occupies less area, less power consumption. The application of microcontrollers is MP3, washing machines.

While designing any embedded system, designers face lots of challenges like as follows,

1. Environment adaptability
2. Power consumption  
3. Area occupied
4. Packaging and integration
5. Updating in hardware and software
6. Security

There are various challenges the designers face while testing the design like Embedded hardware testing, Verification stage, Validation Maintainability.

8. Explain the various form of memories present in a system Various forms of memories are

RAM(internal External)
ROM
PROM
EEPROM
Flash
Cache memory
EEPROM or flash
External ROM or PROM for embedding software
RAM Memory buffers 

Caches (in superscalar microprocessors)

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