I before talked with some experienced engineers and found that a fairly part of them didn’t use or seldom used Emulator. When asking them why, they just simple answered “It is uncertainty”. If it is really so, why are there so many JTAG Emulator in the market? What is the effect of JTAG Emulator?

Moved: This thread is more suitable in <GENERAL> and has been moved accordingly to help your thread/question get the exposure it deserves.

Thank you Tinkster, you did a favor for me, I am sure the "general" forum is more suitable for my question.

If they don’t use JTAG Emulator, I suppose they might follow the steps below to develop their programs:
(1) According to their project, first, they might build a hardware platform which will meet their requirements. If programs are very complicated, they will build an interface for human-computer interaction like a simple LED, a buzzer or ever LCD display.
(2) Write a very simple program, such as light up a led, and keep it blink. Then compile the program and burn it to the chip to verify whether their hardware platform is normal or not.
(3) After the hardware platform is OK, they will start to write the driver programs of the system, but each modification of programs will lead to reburn the programs to chips to verify the chips right or wrong. If there are problems during verifying programs, they might use some debugging methods; for example, send some message to the hypeterminal of the PC through a serial interface to check the running statements of programs.
(4) After that, they will start to write the specific user applications, this section will not refer to the hardware problem, so normally, those questions which appear in programs will be found out.

I hope the above information will solve your question that why engineers don’t use JTAG Emulator.

Linux_bird
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There are various different things described as emulators, but one problem with emulation is that it is not exactly the same as using the thing being emulated. In particular, there may be timing differences.

If the software that you are trying to develop is timing-critical (eg, real time software) then anything that changes timing may be a very bad thing.

I have certainly seen projects waste appreciable time -several man-months- tracking down 'faults' which were not real faults but mere artefacts introduced by using emulators.

Some people see information like that and conclude that it is never wise to use an emulator, some conclude that you must always use extreme caution with emulation and some conclude that the advantages can be so great that there is no alternative but to tolerate this problem as the severe problems only happen to other people (or have, so far).

I agree with what you said,salasi. Actually, there is no absolutely right or wrong with Emulators, but I think the emulators as JTAG debugging tool would have their reasons of existense, at least they could partly help engineers to debug their programs.

Linux_bird
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http://www.embedinfo.com/en