Important Short Questions and Answers: Embedded Software

EMBEDDED SOFTWARE

1. State some advantages of Assembly language?

It gives a precise control of the processor internal devices and full use of processor specific features in its instruction set and its addressing modes.

The machine codes are compact.

With the help of assembly language the basic concepts could be easily studied. Memory required for the system is less.

Minimum assembly languages instruction only needed for device drivers.

2. Write the advantages of high level language?

Standard library functions

Modular programming approach Bottom up design

Top down design Data types

Type checking

Control structures Portability

3. Give the details of TCON SFR.

TR0, TR1 - Timer run control bits 

TF0, TF1 - Timer overflow flags 

IE0, IE1 - Interrupt flags

 IT0, IT1 - Interrupt type control bit

4. Give the details of TMOD SFR?

Mode 1 (M1 = 1; M2 = 0)-16-bit timer/counter (with manual reload)

 Mode 2 (M1 = 0; M2 = 1) -8-bit timer/counter (with 8-bit automatic reload) 

GATE -Gating control

C / T- Counter or timer select bit

5. What is the advantage of a hardware generated delay over a software generated delay?

Software generated delay is unreliable; it may change during compiler optimizations or

depending on the machine on which it is run. Hardware generated delays are precise and is reliable.

6. What is the advantage of a portable hardware delay?

In a portable hardware delay the operating frequencies can be changed dynamically and it is easy for the maintenance of the system.

7. Give the need for timeout mechanism.

When a system has to be created as reliable then it should assure that the system will not get into an indefinite loop. To do this assurance, we need the timeout mechanism. They are loop timeout which is software based and hardware timeout which is based on hardware.

8. Give the uses of timer 2?

          It is used to produce the delay. It is employed in

          1.       Creation of an operating system       2. Real time applications.

9.  Give the types of Multi State Systems?

          1. Multi-state (timed)    

          2. Multi state (input/timed)

          3. Multi state (input)

10.            Give the characteristics of Multi state systems.

They involve a series of system states.

In each state, one or more functions may be called.

There will be rules defining the transitions between states.

As the system moves between states, one or more functions may be called.

11.            What are multi-state timed systems? Give example.

In a multi-state (timed) system, the transition between states will depend only on the passage of time.

A basic traffic-light control system is an example.

12. What are multi-state timed input systems? Give example.

In a multi-state timed input system the transition between states (and behaviors in each state) will depend both on the passage of time and on system inputs.

The autopilot system, a washing machine, or intruder alarm systems are the examples.

13. What do you mean by a host and target machine?

A typical embedded computing system has a relatively small amount of everything, including CPU horsepower, memory, I/O devices, and so forth. As a result, it is common to do at least part of the software development on a PC or workstation known as a host. The hardware on which the code will finally run is known as the target.

14. What is a cross compiler?

A cross-compiler is a compiler that runs on one type of machine but generates code for another. After compilation, the executable code is downloaded to the embedded system by a serial link or perhaps burned in a PROM and plugged in.

15. What is test-bench program?

The test-bench program generates inputs to simulate the actions of the input devices; it may also take the output values and compare them against expected values, providing valuable early debugging help.

16. What is a breakpoint?

A breakpoint is a debugging tool for the user to specify an address at which the program’s execution is to break. When the PC reaches that address, control is returned to the monitor program. From the monitor program, the user can examine and/or modify CPU registers, after which execution can be continued.

17. What is an in-circuit-emulator?

The microprocessor in-circuit emulator (ICE) is a specialized hardware tool that can help debug software in a working embedded system. At the heart of an in-circuit emulator is a special version of the microprocessor that allows its internal registers to be read out when it is stopped.

The in-circuit emulator surrounds this specialized microprocessor with additional logic that allows the user to specify breakpoints and examine and modify the CPU state.

18. What is a logic analyzer?

A logic analyzer is an array of inexpensive oscilloscopes—the analyzer can sample many different signals simultaneously (tens to hundreds) but can display only 0, 1, or changing values for each. All these logic analysis channels can be connected to the system to record the activity on many signals simultaneously.

19. What are the two modes in which logic analyzer can acquire data?

A logic analyzer can acquire data in either of two modes that are typically called state and timing modes.

20. What is a simulator?

A simulator is a software tool that runs on your host and simulates the behavior of the microprocessor and memory in your target system.

21. What is a Monitor?

Monitors are debugging tools which are used to run the software on the actual target microprocessor while still giving a debugging interface similar to that of an in-circuit emulator.

22. Why debugging is a challenge in real time systems?

Real-time programs are required to finish their work within a certain amount of time; if they run too long, they can create much unexpected behavior. The exact results of missing real-time deadlines depend on the detailed characteristics of the I/O devices and the nature of the timing violation. This makes debugging real-time problems especially difficult.