Two Marks Question and Answers
TWO MARKS QUESTION AND ANSWERS
EMBEDDED SYSTEM
1. Define Embedded Systems.
An embedded system is one that has computer hardware with software embedded on it as one of
its most important component. An embedded system is a computing device that does a specific
and repetitive job.
2. Write some applications of Embedded Systems.
Smart card
Missiles & Satellites
Computer Networking
Au to mo tive s
3. What are the classifications of Embedded system?
Small scale Embedded System
Medium scale Embedded System
Sophisticated Embedded System.
4. Give examples for Small, Medium & sophisticated scale embedded systems.
Small Scale Embedded System
Automatic chocolate vending machine
Stepper motor controller for a robotics system
Washing or cooking system
Multitasking toys
Medium Scale Embedded System
Computer Networking Systems
Entertainment systems
Embedded firewall / Router
Signal tracking system
Sophisticated Scale Embedded System
Embedded system s for wireless LAN & for convergent technologydevices.
Security products & high speed network security, gigabit rate encryption rate products
Embedded system for real time video & speech
5. List the categories of embedded system.
Stand-alone embedded systems. Eg. AC, Oven, CD player, TV.
Real-time systems. Eg. Aircraft control, Missile & Satellite control
Networked Information appliances. Eg. Weather monitoring system
Mobile Devices. Eg. PDAs, Smart phones.
6. List the specialties of embedded systems.
Reliability
Performance
Power Consumption
Cost
Size
Limited User interface
Software upgradation capability
7. List the factors to be considered while evaluating the processor for embedded system.
Clock Speed
Length of Registers
Number of Registers
Width of Data and Address bus
Internal RAM & ROM
Interrupt lines
No. of programmable I/O lines
On-chip peripherals such as Timers, UART, ADC, DAC, etc.
8. What are the hardware components of embedded systems?
Input devices, Interfacing/Driver circuits,
Pr o ce sso r
Ti mer s
Interrupt Controller
M em or y
Serial/Parallel Ports
Output Interfacing/Driver circuits
Power supply,
Reset & Oscillator circuits.
9. Define processor.
A processor is a Chip, which implements a process or processes as per the command given to it.
10. Define Watch Dog Timer
Timing device that resets the system after predefined Time outfit is activated with in few clock
Cycles after the Power up.
11. Compare CISC and RISC processor.
CISC:Complex Instruction Set Computer (CISC)
Aim of designing CISC processor is to reduce the softwarecomplexity by increasing the
complexity of the processorarchitecture. CISC has large no of instructions. Instructionsrequired
to do a job is less and hence, the memoryrequirement in less. No. ofregisters are available in
CISCprocessor is very less. Eg. Intel x86 family and Motorola 68000 series processors.
RISC:
Reduced Instruction Set Computer (RISC)RISC has limited no. of instructions and hence,
complexoperation is carried out through sequence of more simpleinstructions. Large number of
registers is required in RISCprocessor. Another important feature of RISC processor ispipelined
instruction execution.Embedded systems generally use RISC processor.
Eg. ARM, ATMEL, AVR, MIPS, Microchip’s PIC family processors,Power PC and Sun
SPARC processor.
12. What are the processor architectures in embedded systems?
Von-Neuman Architecture: This architecture has common memory for both data and program
codes.
Harvard Architecture: This architecture has separate memory for data and program codes.
13. What is microcontroller?
A microcontroller is a unit with a processor. It is a single chip VLSI unitwhich, thought having
limited computational capabilities, possesses enhanced input-output capabilities and a number of
on-chip functionalunits.
14. What are the functional circuits of a microcontroller?
The functional circuits of a microcontroller are,
Pr o ce sso r
Data & stack in internal RAM
Timers & Watchdog timer
ROM / PROM / EPROM
External Memories Interfaces
Interrupt Controller
I/O Ports Control & Interfaces / Drivers
Serial UART communication port
15. What are the features of DSP?
A DSP provides fast, discrete-time, signal processing instructions. It hasvery large instruction word (VLIW) processing capabilities, it processesSingle Instruction Multiple Data (SIMD) instructions fast, and it processesDiscrete Cosine Transformations (DCTs) and inverse DCTs (IDTs) fast.
16. What is GPP & ASIP?
GPP: A processor from a number of families of processors, microcontroller,embedded
processors and DSPs having a general purpose instruction setand readily available compilers to
enable programming in a high level language is called a General Purpose Processor (GPP).
ASIP: A processor designed for specific application on a VLSI chip is calledan Application
Specific Instruction Processor.
17. What is ASSP?
Application Specific System Processor is a processing unit for specifictasks, for e.g. Image
compression and that is integrated through thebuses with the main processor in an embedded
system.
18. What is System-On-Chip?
A system on a VLSI chip that has all of needed analog as well as digitalcircuits. For example,
mobile phone.
19. What are the various forms of system memories?
Internal RAM
Internal ROM / PROM /EPROM
External RAM
Internal & External Caches
External ROM / PROM
RAM Memory buffers
Hybrid memory such as E2PROM, NV-RAM or flash memory
21. List the important types of Displays.
Light Emitting Diode (LED)
Liquid Crystal Display (LCD)
Thin Film Transistor (TFT) Display
Organic Light Emitting Diode (OLED)
22. List the important Serial communication protocols.
Inter-integrated Circuit (I2C)
Serial Peripheral Interface (SPI)
Universal Serial Bus (USB)
Controller Area Network (CAN)
23. List the important communication interfaces used in embedded systems.
Serial interface using RS232
Serial interface using RS422/RS485
Universal Serial Bus (USB)
In f r a re d
Eth e rn e t
Wireless interface using IEEE 802.11 (WLAN)
B lu e to oth
ZigBee IEEE 802.15.4
24. Define interrupt handler.
It is a unit that handles the processor operations arising out of an interrupt from a source.
25. What is watchdog timer?
It is a timer that timeout from which resets the processor in case the program gets struck for an
unexpected time.
26. What is reset circuit and power-up reset?
The reset circuit activates for a fixed period and then deactivates. It helpsthe processor to start
the processing of instructions from a startingaddress.Power-up reset vector also provides a
starting address which is differentfrom that provided by a reset circuit
27 What are the steps required for converting assembly language intoa ROM image?
Assem b le r
Lin ker
Loa d e r
Locator & Device Programmer
28 What is ROM image?
The final stage software is also called ROM image, because just as animage is a unique sequence
and arrangement of pixels, embeddedsoftware is also a unique placement and arrangement of
bytes forinstructions and data.
29 . What is the use of code optimizer?
Code optimizer is used in the conversion of high level language into a ROMimage for optimizing
the code before linking.
30 What is Compiler?
Compiler is a software tool that converts a high level program (writtenusing programming
languages like C, C++, Java, and so on) into an objectcode.
31 What is Assembler?
Assembler is a software tool that converts an assembly program (writtenusing mnemonics of a
processor, i.e., instruction set of a specificprocessor) into an object code.
32 What is Timer and counting devices?
A Timer gets the inputs from the internal clock of a processor or from system clock and
generates a required time delay.
Counting device is a unit for getting the count-inputs on the occurrence of events that may be at
irregular intervals.
33 What are the types of Timer?
There are two types of timer. They are,
Hardware timer
Software timer
34 What are the different states in a timer?
The different states in a timer are,
Reset State
Idle State
Present State
Overflow State
Active or Blocked State
Done State
35 Is it necessary to have a hardware timer device in a system? How does it work?
Yes, it is necessary to have atleast one hardware timer device in a system. It is used as a system
clock. The hardware timer gets the input from a clock out signal from the processor and activates
the system clock as per the num ticks preset at the hardware timer
36 Mention the types of data Transfer in USB Bus
Controlled Data Transfer , Bulk data Transfer, Interrupt driven data Transfer, Isosynchronous
Transfer.
37 what is Real Time Clock?
RTC is aclock that causes Occurance of Regular intervals of interrupt on its each Ticks.Timing
device once started never resets .It is ysed in System to save Current time & Date.
38 Give the Classification of Serial & Parallel port of IO devices.
Synchronous Serial Input
Synchronous Serial Ouput
Asynchronous Serial UART Input
Asynchronous Serial UART Output
Parallel Port one bit Input
Parallel One bit output
Parallel Port Input
Parallel Port Output
39 Compare Synchronous & A Synchronous communication
In Synchronous Communication a Byte or Frame is Received or Transmitted at Constant Time
interval with Uniform Phase difference .data is Sent at Fixed Time interval. Eg Frames sent over
LAN .
In A Synchronous Communication a Byte or Frame is Received or Transmitted at variableTime
interval .Eg RS 232 Communication between two UART devices.
40 List the Parallel communicating Buses.
ISA ,PCI( Peripheral Component Interconnect ), ARM
42 Mention the processor Features in Embedded System
It should Operate at high clock Speed
Provide High computing performance with Pipelinning & SuperScalar Architecture
Provide Fast Context Switching in Multitasking System.
43 what is DMA controller?
It Facilities a multi byte data transfer or Block of data transfer between the External device &
System.
Modes of Operation:
Single Transfer at time & then release IO bus hold on the system bus after each transfer
Burst transfer at time & release of IO bus hold on the System Bus.
Bulk transfer & then release of IO bus hold on the System Bus after the Transaction is
Completed.
44 what is Device driver ?
Device driver is a program that controls a particular type of device that is attached to your
computer. There are device drivers for printers, displays, CD-ROM readers, diskette drives, and
so on. A device driver essentially converts the more general input/output instructions of the
operating system to messages that the device type can understand. Virtual device drivers handle
software interrupts from the system rather than hardware interrupts. Virtual device driver for
each main hardware device in the system, including the hard disk drive controller, keyboard, and
serial and parallel ports.are used to maintain the status of a hardware device that has changeable
settings.
45 what are the Serial Communicating Protocol?
I^2 C Bus, CAN Bus, USB Bus.
46 Give Memory allocation Schemes in a system
Static Memory Allocation : Allocated during Compile Time… Entire space in memory is
Allocated.
Dynamic Memory Allocation : Allocated during Run Time….. Blocks of Memory will be
allocated.
47 what are the features of USB?
It can be Plugged , Configured & used, reset & Reconfigured it can Share Bandwidth with other
devices,detached & Reattached. Attaching & detaching can be done without Rebooting.it can be
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