Need to force single byte out COM1 using XP

[tpmoody]

I hope I am making sense.
I'm not a novice but I am getting stumped a little. I need to force a single byte out a COM port when I want to. Even if I turn off the fifo, XP still seems to send the byte when it wants to, not when I tell it to. Yes, I have flushed the buffer, but it still gets sent at some random time in the future. My real question is can I write a flexible COM device driver with the DDK? Will it allow me to "revert" back to a point that I can write my own ISR so I can force a byte out the COM port when I want it to???
Tim Moody
PS I use C++ and Visual Studio .NET 2003 on an XPPro box

 

[Salem]

Elevating your process priority to "real-time" level might help, but other than that you have to live with a certain amount of discretion on the part of the OS as to when it does things.

If you really want that level of control over the timings, then you're going to have to use a real time operating system. A normal desktop OS just isn't going to cut it.

Why is the timing so critical by the way?


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[tpmoody]

Salem(is that Oregon),
My thoughts exactly, and I do long for my Unix,QNX,Linux environment. This can be a little frustrating. Thanks for your input.
Tim
PS Timing is so critical because of the piece of garbage peripheral I have to communicate with.

With Linux I can make it sing, with Microsoft I can make it puke.
Feel free to quote me, no charge