[mythtvnz] Serial IR blaster on USB to serial cable

[David Zanetti]

On Sun, 2010-08-22 at 14:37 +1200, Robin Gilks wrote:
> > Hi guys,
> >
> > I found a cheap serial IR blaster online the other day and bought it.
> > After it arrived I realised that I don't have a serial port on my
> > computer!  Just a parallel one - why you'd want a parallel over a serial
> > I don't know.  So I borrowed a USB to serial cable from a friend and it
> > is recognised by the system.  Problem is that when you install lirc and
> > you activate the blaster option it asks you for the serial port you are
> > using and the USB version is not an option.  Anyone know whether I can
> > actually make it work using this cable and what config file I might need
> > to modify to get the correct port working?
> 
> No - it won't work. It *MUST* be a real serial port since if you look at
> the wiring it uses either the RTS or DTR output control lines and the lirc
> driver waggles them 40,000 times a seconds with great accuracy. You just
> can't do that with a USB stack.

FTDI FT232* USB Serial chip in bit-bang mode is more than capable of
doing this. It would be an interesting project to make it work. libftdi
may help you in this regard :)