[mythtv-users] AM2 Motherboard with PCI slots galore

Yan Seiner yan at seiner.com
Thu Feb 14 17:19:51 UTC 2008

Ronald Frazier
>>  I'm not sure what you mean by a "true" serial port. A USB-Serial
>> adapter
>>  can be used for any application that meets the RS-232 spec, assuming
>> you
>>  have good drivers for the adapter. It's the blasters that are not
>> "true"
>>  serial devices.
> Well, if it doesn't behave the way a serial port on the motherboard
> would, then I'd say it's not a "true" serial port. Granted these
> blasters may or may not be outside the spec of what a serial port is
> SUPPOSED too do. However, every onboard serial port I've ever toyed
> with has behaved the same way (my lirc IR device works the same on my
> brand new computer as it did on my 10 year old computer). It would
> seem to me that such broad "out-of-spec" compatibility doesn't happen
> by accident. I would suspect the serial port standard goes beyond
> simple RS-232 compatability (but I'm just speculating...I have no idea
> what sort of standards actually exist for that)

Basically LIRC uses the serial port as GPIO (general purpose IO) rather
than a serial port, as it doesn't use the send/receive lines at all.

Instead it draws power from one pin, and strobes another pin (I think this
is the Carrier Detect pin, which is a part of the spec.)

Since the CD is part of the spec, it works with most serial ports as most
hardware ports implement CD.  Many software ports do not (yes there are
ports that use software to emulate the hardware.)


Windows is like a canary in a coal mine, it's the first thing to die on
your network.

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