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Explanation of F12 Subdevice number
Posted: Fri Feb 18, 2011 7:41 am
by NEC1
On an Avanti CD player remote which uses the F12 protocol, I find that the learned commands result in odd OBCs having a Subdevice of 0 while the even OBCs have a Subdevice of 1.
All of the codes from the remote in question had Device 3.
Also, DecodeIR.dll version 2.41 was used.
Posted: Fri Feb 18, 2011 3:55 pm
by vickyg2003
The F12 protcol doesn't seem to have a Subdevice, its a device, a checkbit and an OBC,
If you suspect the F12 is not the correct decode you might want to capture a complete set of codes and post the IR(s) so that someone can take a look,
Posted: Sun Feb 20, 2011 1:07 am
by 3FG
The F12 IR protocol is not well documented. As Vicky says, it features a 3 bit device number, an 8 bit function (OBC) number, and a check bit. DecodeIR.html simply says D:3, C:1, F:8. I've now looked at a number of learned F12 signals, and it appears that the bit C is what is normally termed a parity bit, in this case a even parity bit.
That means that C is set to zero if the number of 1 bits in the 11 bits of D+F is even, and set to 1 if the number of 1 bits is odd.
DecodeIR.dll displays the C bit as a subdevice bit, and that is convenient for e.g. Pronto Hex representations. However, the 00 1A executor we use for F12 appears to calculate the C bit, and so it isn't necessary to specify a "subdevice" in RM or KM.
In other words, just ignore the subdevice reported by DecodeIR.dll, and just use the device number.