i've got a question relating to the lirc drivers -- since i'm usually
out of serial ports, but often have a spare parallel port, it would be
convenient to move my IR receivers to the other type of port.
looking at the drivers, along with my limited knowledge of how the
ports themselves work, it seems that the serial driver times the
transitions of the DCD line, and the parallel driver times transitions
on the ACK line. so, in that regard, it seems they're very similar.
however, it seems to me that the DCD line will give an interrupt on
both up and down transitions, whereas the ACK line on the parallel
port will only interrupt on one transition. am i correct? if this is
so, how can the parallel driver time the duration of both the high and
low states of the ACK line? am i missing something?
of secondary concern is power -- i haven't yet looked at the current draw
specs -- i'm not sure that the parallel port is capable of providing
"phantom power", as is drawn from RTS in the serial designs. that
would be a nuisance, but wouldn't be insurmountable. (i'm actually
a little surprised, looking at the serial hardware circuit for the serial
receiver, that power comes from RTS. the radio shack module recommends
5V Vcc, and RTS might be as high as 10 or 12, no?)
paul fox, pgf@... (arlington, ma, where it's 34.3 degrees)