Evgeni,
> i am writing a device driver for an eib (European Instalation
> Bus) device.
> It communicates with a serial port. I wrote my own module
> which I load with
> rt_com and communicate with the device (19200 8n1)- it sends
> the computer a
> byte and the computer sends it back. The problem is that I
> want to make the
> response time of the serial device smaller.
>
> see i connected an osciloscope to the serial port and
> measured delay of 2.2
> miliSecs between the time the driver gets the byte and send
> the answer. I
> need to bring the time down to a bit less than 150 microSecs.
I will not profess to fully understanding your complaint, but it
sounds like you are saying that you are receiving a single byte and that it
appears to take an inordinately long time. If that is the case, you have
probably hit a fairly common problem with rt_com.
The problem is that there are FIFOs on most modern UARTS. rt_com,
by default, enables these FIFOs. If the FIFOs are enabled, a receive
interrupt is not generated until either the FIFO fills, or a time-out has
occurred. You probably want to disable the FIFO for your application, or
else reduce the time-out. A quick browse of the rt_com code will show how
this is done (I do not remember off the top of my head).
Regards,
Steve
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