[mythtvnz] Serial IR blaster on USB to serial cable

[Brett]

On Fri, 2010-08-27 at 23:33 +1200, Robin Gilks wrote:
> > 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 :)
> 
> Drivers... drivers drivers drivers...
> 
> There must be a 101 ways of interfacing an infrared LED to a PC whether
> its a serial port, parallel port (only just fast enough!!), PCI bus (using
> one of the select lines or mapped I/O) or lots of capable USB devices.
> 
> For external USB stuff I'd prefer an Atmel 8 bit AVR micro doing USB
> decode in software and bit banging the output to the LED - could download
> different modulation code sets on the fly then. Someone still has to write
> an lirc kernel device driver for it though so I'd use either a real serial
> port or a USB MCE remote that has 2 3.5mm jacks in the back for IR
> blasters (I'm using the latter in 2 places!!).
> 
But FTDI provide linux drivers (not kernel) & these devices are also in
lots of devices. I think some iMon use FTDI but then again that does not
recommend them does it !