All,

I have a Motorola WR850G and as explained in the wiki have found the input pads for GPIO 4.  Using the gpiotest program I have turned it on and off and found that I can toggle a 5v output on it (note: not a 3v).

I want to use this GPIO as an input.  I am planning to use it with LIRC and plan to connect a IR receiver circuit to it.  Elsewhere on this forum, there is a precompiled LIRC working with gpio (both for sending IR and receiving IR). I intend to use that to receive IR. 
The circuit without an IR has 5v on it and when blasted with IR gives me 3.x volts (measured using a multimeter).  I am not sure if it is bringing/pulling it down to 0v and my multimeter is simply showing an average !

I don't know much about electronics. The questions I have is:
- How do I know whether a gpio port is in or out or supports both ?
- Can I connect this IR receiver circuit into the gpio pad without blowing it up ?
- In terms of a gpio input, does it work by sensing a presence or absence of voltage at the pad ? And is this 5v or 3v ?
- Will I be able to read the 0-5v pulses coming from the IR receiver ? 

Thanks for your help,
Arun

Just add a resistor of about 1k to limit the current. The meter would show an average with any serial data, including IRDA.
Could you just connect it to a serial port? I don't think driving IRDA from scratch would work very well.