On Wed, 27 Dec 2000, David Pearson (SKYTRONICS) wrote:

> Hi,
>         To all the PC programming experts a couple of questions.
> I'm transferring data from a CCD image sensor for display on a PC via the
> parallel port.  Works fine, 8 bit gray scale. 400 x 280 pixels.  I'm using a
> F877 to transfer data to the PC using the parallel port in Bi-directional
> mode.  On the PC end, I'm using Delphi 5 with my own Assembly Portin,
> Portout, Porttest routines.  Plotting pixels using the Plotxy functions.
>
> The problem, it's very slow.  It takes ~12 seconds to plot a frame on a
> Pentium 120.  From what I've read, the maximum toggle rate I can expect on
> the parallel port is 500 nsec to 2 usecs, depending on what you read.  Even
> so, I'm seeing times between setting a bit on the parallel port by the F877
> to the time the PC recognizes the signal of about 15 usecs.  Also,  the
> plotting routine itself is slow, about 6 seconds to plot the 400 X 280 frame
> when plotting a test grayscale pattern, no port IO, just incrementing the
> plot value.
>
> Does anyone have any ideas on how to speed things up?  I need a Windoze
> 95/98 environment using either Delphi or VB.
> Any ideas on how to speed up the data transfer?  Faster portIO?  Faster
> Plotting in Delphi?
> It seems crazy to me that my $5.00 PIC has to wait for a 120 MHz machine to
> do data transfers.  Is the Windoze environment that inefficient?
Yes, it is. I would try it (I does is anyway) using pure DOS. No
hassle. Unfortunately, Delphi can be forgotten, but there is e. g. TP 5.5
(for free), or FreePascal. Did you ever consider interrupt-driven I/O?

Regards,
Imre

>
> Any ideas and help is appreciated and may be useful to other group members.
>
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