"Craig Thrall" <[EMAIL PROTECTED]> wrote on 00/02/21 12:55 am:
> The device I need to talk to requires me to make DTR high for 25ms, then
> low, then RTS high for a specified amount of time, etc. I read that
> opening and closing the port can flip DTS between +3V and +6V, but I need
> to control RTS independently of DTR...if it means I have to do a little
> register manipulation, so be it. :)
Two problems come to mind. The non-standard DTR voltage will more than
likely not work with your device. The easiest way to work around that is to
stick a 3V zener diode inline to drop the voltage; I had to do this for my
cellphone.
Actually maybe I will rethink about the DTR line not being independently
programmable. I don't recall tracing it back to a signal so I can't say for
certain whether it is always 6V when the 232 driver is powered. In my
experience it is, which will lead to your second problem which is that of
course powering off the driver will leave no signal on the RTS.
I'll tell you that you still have the TXD line that you can use as a general
purpose I/O -- and in my case that is what I had to use for what sounds like
a similar project as yours.
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