Visual Basic timer help

Hey guys. I asked this once before and never really figured anything out. I thought I had gotten out of doing this, but my friend called me today looking for his program. So here it goes.

My friend is a chiropractor and he needs a program to time reflexes. What he wants is for the screen to change color, then the user hit spacebar as fast as he/she can and then record the time it took to do so. I need to record the time down to the thousandths (.999). The timer in VB only does the hundredths (.99) and I hear isn't the most accurate thing in the world. Is there a way to get it down to the thousandths? Someone gave me a link to another VB timer but it was very confusing and I did not get it to work at all. Any help would be great!!!!!! Thanks!

Here is the program:

User sits at screen. :)
Screen changes from blue screen to green screen...counter starts
User hits spacebar as soon as he/she sees the green screen
When spacebar hit, counter stops.
Output info.

Neal

Quote:

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Originally posted by ZF_NeAlvey
Hey guys. I asked this once before and never really figured anything out. I thought I had gotten out of doing this, but my friend called me today looking for his program. So here it goes.

My friend is a chiropractor and he needs a program to time reflexes. What he wants is for the screen to change color, then the user hit spacebar as fast as he/she can and then record the time it took to do so. I need to record the time down to the thousandths (.999). The timer in VB only does the hundredths (.99) and I hear isn't the most accurate thing in the world. Is there a way to get it down to the thousandths? Someone gave me a link to another VB timer but it was very confusing and I did not get it to work at all. Any help would be great!!!!!! Thanks!

Here is the program:

User sits at screen. :)
Screen changes from blue screen to green screen...counter starts
User hits spacebar as soon as he/she sees the green screen
When spacebar hit, counter stops.
Output info.

Neal

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Something like this would be easy. Look up the 'GetTickCount' windows API procedure in the API viewer. It returns the number of milliseconds elapsed since Windows last started, and its as accurate as your computer can be!

I could have source code for such a program posted in 15 minutes or less easily!

All you need is a timer control on your form!

Code:

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Option Explicit

Private Declare Function GetTickCount Lib "kernel32" () As Long

Dim lngOldTime As Long
Dim lngNewTime As Long
Dim lngResult As Long

Private Sub Form_Load()

    'Disable the timer when loading
    Timer1.Enabled = False

    Me.Show
   
    Randomize 'This procedure resets the random number generator
   
    'This equasion returns a radom value between 5000 and 10000, and can be found in the msdn help file
    'for the 'Rnd' function. This makes the form's backcolor change at a random time between 5 and 10 seconds.
    Timer1.Interval = Int((10000 - 5000 + 1) * Rnd + 5000)
   
    'Make the backcolor blue and enable the timer.
    Me.BackColor = vbBlue
    Timer1.Enabled = True

End Sub

Private Sub Form_KeyDown(KeyCode As Integer, Shift As Integer)

    '32 = the space bar
    If KeyCode = 32 Then

        'If the user presses the space bar before the screen turns green, the first variable wont be set.
        If lngOldTime = 0 Then
       
            Timer1.Enabled = False
            MsgBox "You pressed the space bar before the screen turned green"
           
            Randomize
            Timer1.Interval = Int((10000 - 5000 + 1) * Rnd + 5000)
            Timer1.Enabled = True

        'If the screen has turned green
        Else
           
            'Get the new time.
            lngNewTime = GetTickCount
           
            'Calculate the time elapsed.
            lngResult = lngNewTime - lngOldTime
           
            'Output the result.
            MsgBox Str(lngResult) & " milliseconds elapsed"
           
            'Reset the variables
            lngOldTime = 0
            lngNewTime = 0
           
            'Make the backcolor blue again, randomize the interval, and start the whole thing again!
            Form1.BackColor = vbBlue
           
            Timer1.Enabled = False
            Randomize
            Timer1.Interval = Int((10000 - 5000 + 1) * Rnd + 5000)
            Timer1.Enabled = True

        End If

    End If

End Sub

Private Sub Timer1_Timer()

    'When the timer goes off, make the form green and set the first variable to the current time.
    Form1.BackColor = vbGreen
    lngOldTime = GetTickCount

End Sub

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Hmm, was that less than 15 minutes?

the problem with the standard timer/time functions is the poor resolution and/or accuracy. so for reflex gauge type applications you want to use "multimedia timers".

you can access the mm timer by api directly but i dont remember all the details about using APIsin VB so i recommend some activex controls that encapsulates multimedia timers. here is one:
http://download.com.com/3000-2401-88...ml?tag=lst-0-1

Thanks guys for the replies. Your code looked impressive. I'm getting ready to cut/paste it and take a look at it. Thanks for the help!

hu flung dung,

That is really impressive. Seems to work like a charm. I really appreciate it. I just need to add a few more things to it and he should be good, or atleast I hope he is. Thanks again!

the problem with the timer control is that there is no garuntee it will fire at the correct interval, but that it wont fire BEFORE the interval. so if your machine is bogged down, it may fire well after the interval. You can get free 'dll' files that implement far more acurate timers, or you can use the multimedia timers, etc.

Quote:

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Originally posted by dighn
the problem with the standard timer/time functions is the poor resolution and/or accuracy. so for reflex gauge type applications you want to use "multimedia timers".

you can access the mm timer by api directly but i dont remember all the details about using APIsin VB so i recommend some activex controls that encapsulates multimedia timers. here is one:
http://download.com.com/3000-2401-88...ml?tag=lst-0-1

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DWORD timeGetTime();

but that is for C++

Quote:

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Originally posted by df
the problem with the timer control is that there is no garuntee it will fire at the correct interval, but that it wont fire BEFORE the interval. so if your machine is bogged down, it may fire well after the interval. You can get free 'dll' files that implement far more acurate timers, or you can use the multimedia timers, etc.

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If you looked at my code, then you would know that I'm using the GetTickCount procedure to time reflexes, and the timer control to randomize the time it takes for the screen to turn from blue to green.

It is impossible to have a perfectly accurate timer DLL or procedure because your system timer is not perfectly accurate! GetTickCount is no more or less accurate than any other timing-related Windows API call! You system timer, however, would be accurate to within less than 10 milliseconds!. I don't think perfect accuracy is important when just timing somone's reflexes (it probably takes more than 10 milliseconds to hit the space bar anyhow)!

Quote:

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Originally posted by hu flung dung


If you looked at my code, then you would know that I'm using the GetTickCount procedure to time reflexes, and the timer control to randomize the time it takes for the screen to turn from blue to green.

It is impossible to have a perfectly accurate timer DLL or procedure because your system timer is not perfectly accurate! GetTickCount is no more or less accurate than any other timing-related Windows API call! You system timer, however, would be accurate to within less than 10 milliseconds!. I don't think perfect accuracy is important when just timing somone's reflexes (it probably takes more than 10 milliseconds to hit the space bar anyhow)!

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but multimedia timer APIs are supposed to be very accurate, certainly more so than reguarly API timers

Quote:

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Originally posted by dighn


but multimedia timer APIs are supposed to be very accurate, certainly more so than reguarly API timers

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But how can you make a software timer more accurate than your own system timer?

Quote:

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Originally posted by hu flung dung


But how can you make a software timer more accurate than your own system timer?

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i dont know. from what i read, multimedia timer APIs uses the more precise timing devices.

Quote:

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Originally posted by dighn


i dont know. from what i read, multimedia timer APIs uses the more precise timing devices.

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The only timing device in your computer is your system timer! All timing software/code is based on it! These API's you speak of cannot be more accurate than your own system timer!

Can you please show me the source code for a multimedia timer that claims to be more accurate than the Windows API?

actually multimedia timer is part of the windows API

here's some information on it: http://www.microsoft.com/hwdev/platf...c/mm-timer.asp

as u can see there are a lot of timing devices in your computer

Quote:

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Originally posted by dighn
actually multimedia timer is part of the windows API

here's some information on it: http://www.microsoft.com/hwdev/platf...c/mm-timer.asp

as u can see there are a lot of timing devices in your computer

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Ah, cool!

Thanx for the heads up! I did a search on msdn.microsoft.com and found the 'timeGetTime' procedure, which has more accuracy (its using the multimedia timer) and it works exactly the same way!

Here's the declaration:

Code:

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Private Declare Function timeGetTime Lib "winmm.dll" Alias "timeGetTime" () As Long

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However, they've also mentioned that the QueryPerformanceCounter and QueryPerformanceFrequency functions can give you even more accuracy than the multimedia timer because their based on the clock cycles of your processor!

I posted something, but nevermind. I found out why what I posted worked. :)

Quote:

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Originally posted by hu flung dung

However, they've also mentioned that the QueryPerformanceCounter and QueryPerformanceFrequency functions can give you even more accuracy than the multimedia timer because their based on the clock cycles of your processor!

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awesome, I know what I'll use next time :D

thnx

i think queryperformancecounter,etc is just the RDTSC, which would mean only processors above a certain model would have it (but then who still has old pentiums + 486's anyway)?

interersting note in the MSDN docs

On a multiprocessor machine, it should not matter which processor is called. However, you can get different results on different processors due to bugs in the BIOS or the HAL. To specify processor affinity for a thread, use the SetThreadAffinityMask function.