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Real-time timer

Posted on 2001-08-06
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Last Modified: 2010-04-06
I need a better timer than the TTimer component. I know there is no perfect timer under Windows 95, but what the TTimer does is quite unacceptable. (The TTimer gives on a 100 MHz Pentium, with the timer interval set to 1,  about 24 timer events per sec -- instead of 1000! Note that the test application was 'honest', doing nothing else in the OnTimer event handler than incrementing a counter.)

I have had the followings ideas.

1. Modifying the priority of the main thread, with the following code in the OnCreate method of the main form:

  mythread:=GetCurrentThread;
  SetThreadPriority(mythread,THREAD_PRIORITY_TIME_CRITICAL);

It makes ABSOLUTELY no difference.


2. Using the SetTimer API function with callback function instead of message posting. I haven't tried it, because the Win32 help says the following:

"When you specify a TimerProc callback function, the DispatchMessage function simply calls the callback function instead of the window procedure. Therefore, you need to dispatch messages in the calling thread, even when you use TimerProc instead of processing WM_TIMER."

So I have the feeling that it won't help me either.


3. Using a driver-level IRQ callback function.

I'm able to handle the IRQ interrupts under Delphi, using an external VxD which can call my Delphi code as callback function when an interrupt arrives, but I don't know whether the timer works with IRQ, and if so, what IRQ should I handle; I'm also not sure that the Windows 95 will share this IRQ with my VxD.


Waiting for ideas and comments,
Adam
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Question by:biroadam
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7 Comments
 
LVL 3

Accepted Solution

by:
tongalite earned 800 total points
ID: 6354998
Hi,
There are some timer comps about, I have a couple which I downloaded... a multimedia timer and a threaded timer (supposed to be very accurate to within 1 millisecond) that's supposed to do what you require. Untested yet though by me... Can't remember where I downloaded them but if you leave a temp e_mail address I will send them to you if you want.
have fun!
T.
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Author Comment

by:biroadam
ID: 6355106
Hi tongalite!

Sounds pretty good!
My e-mail address is biroadam@softhome.net, I'm waiting for the components.

Best regards,
Adam
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LVL 27

Expert Comment

by:kretzschmar
ID: 6355168
get this sample from simonet

entitled

How To Create High Precision Timers (Multimedia timers)
This project is aimed towards those that think Delphi's TTimer is not precise enought. The solution for that is to create a much more precise and reliable timer, a multimedia timer. This how-to project will teach you how to work with them and discuss when to use a multimedia timer and when to use a system timer (TTimer).  


http://www.bhnet.com.br/~simonet/archive/mmtimer.zip
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LVL 22

Expert Comment

by:Mohammed Nasman
ID: 6355428
Hello

  you can find alot types of timers at torry site, and most of them free

http://www.torry.net/timers.htm

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Author Comment

by:biroadam
ID: 6355586
Hi everybody!

The problem is actually very simple, there are two Windows API functions designed especially for realtime (multimedia) applications, called TimeSetEvent and a TimeKillEvent.

These functions work with a callback function rather than windows messages, and so they are quite accurate.

Actually I realised this reading the sample sent by kretzschmar, however the question is locked by tongalite.
Since I guess tongalite's answer is also correct (but I haven't received the components yet), I'll wait for it.

Thanks to everybody,
Adam
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LVL 3

Expert Comment

by:tongalite
ID: 6356687
Sorry guys.... (and gals) Must have hit the proposed answer button when all I intended was to make a comment. I'll try not to let that happen again.

Adam,
The comps have been mailed.... Hope they are of use to you.
T.
0
 

Author Comment

by:biroadam
ID: 6356834
Hi tongalite,

As I was sure, your answer was as well as the others. There was only a TIMING problem...

Thank you again,
Adam
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