SoundGraph iMON PAD (15c2:ffdc)

[Scott L. <sl...@sl...>]

I have the following USB device:

    ID 15c2:ffdc SoundGraph Inc. iMON PAD Remote Controller

which I've learned from lirc-imon.c does IR decoding on the chip (older
iMON PADs do not).

I've had a frustrating experience trying to get this thing to work.
Here's what I've found:

(1) using the included remote and lircd.conf.imon-pad, most of the
controls work most of the time. However,

(1a) the arrow pad is a joystick device (many potential codes), and
Corrin's up/down/left/right codes rarely occur. It looks like lircd does
not support this type of device except by exhaustively listing all
possible codes and assigning commands to them; is that correct?

(1b) again using the included remote, I see single-bit errors roughly
10% of the time. Is this typical of other people's experience, either
with this device or with others? Is there any error correction mechanism?

(2) The included remote sucks (too many buttons and bad ergonomics), so
I bought a TiVo remote. I can't get it to work.

(2a) The codes I receive seemingly have nothing to do with the ones in
http://lirc.sourceforge.net/remotes/tivo/TIVO_Series_2. I suspect the
on-chip decoding and lirc's software decoding result in completely
different values. Is this correct? Maybe that should be more clear in
the documentation and configuration file format.

(2b) The TiVo codes I receive are of the form:

    \x00\x1f\xee\xce\x33\x73....\xff\xff(\x00\x1d\xff\xff)*

In other words, they're 12 bytes long (six common header bytes, four
bytes which vary by button, two common trailer bytes) plus zero or more
occurrences of a four-byte repeat code. The driver sends 4-byte codes,
so the most important part straddles two reads. Unfortunately, lirc
seems to be expecting to receive one remote code in one read:

                        if((hw.rec_mode==LIRC_MODE_CODE &&
                            hw.code_length<bit_count(remote))
                           ||
                           (hw.rec_mode==LIRC_MODE_LIRCCODE &&
                            hw.code_length!=bit_count(remote)))
                        {
                                return(0);
                        }

(2c) Error rates on the TiVo remote are unacceptably high. The longer
code may play a role. I also wonder if the decoder is only suitable for
certain types of IR encodings. Any ideas if this is true / easy way to
see what the chip is designed for, the included remote sends, or the
TiVo remote sends?

I'm close to considering this IR hardware hopeless. Given that I have
one serial port (and only a motherboard header for that; no D-SUB), one
parallel port, and plenty of USB ports, what's the best option for a
receiver for a TiVo remote + a transmitter for a General Instrument DCT2244?

Best regards,
Scott