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The Apple protocol revisited

 
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Barf
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Joined: 24 Oct 2008
Posts: 1276

PostPosted: Sun Nov 29, 2020 5:57 am    Post subject: The Apple protocol revisited Reply with quote

The Apple protocol, both in IrpTransmogrifier and in DecodeIR, goes

Code:
{38.4k,564}<1,-1|1,-3>(16,-8,D:8,S:8,C:1,F:7,PairID:8,1,^108m,(16,-4,1,^108m)*){C=1-(#F+#PairID)%2,S=135}[D:0..255=238,F:0..127,PairID:0..255]


A RemoteCentral person wrote me that he has been encountering Apple devices using some other Ds. It turns out that if the D has an odd number of ones, the above definition will have the wrong C. So the suggestion is to change the definition to

Code:
{38.4k,564}<1,-1|1,-3>(16,-8,D:8,S:8,C:1,F:7,PairID:8,1,^108m,(16,-4,1,^108m)*){C=1-(#D+#S+#F+#PairID)%2,S=135}[D:0..255=238,F:0..127,PairID:0..255]

which appears to be consistent with the Apple devices (and it also looks more symmetric).

Anyone like to comment on this? What is the UEI executor (01E0) doing?
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The Robman
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Joined: 01 Aug 2003
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Location: Chicago, IL

PostPosted: Sun Nov 29, 2020 2:26 pm    Post subject: Reply with quote

I just did a breakdown of the 3 known variants of the UEI executor, and the 1 JP1 homemade executor here:

http://www.hifi-remote.com/forums/dload.php?action=file&file_id=26180
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Rob
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3FG
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Joined: 19 May 2009
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PostPosted: Sun Nov 29, 2020 3:11 pm    Post subject: Reply with quote

I agree that including D and S in the parity bit makes sense.

There are at least 3 UEI 01E0 executors, but all of them expect that the parity bit is explicitly included in the first variable byte. The executor doesn't calculate the parity bit. RMIR does the calculation, so we would need to change protocols.ini.
ETA: I didn't notice Rob's post before I posted.
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The Robman
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PostPosted: Sun Nov 29, 2020 4:19 pm    Post subject: Reply with quote

The newer 2 UEI executors include a vector call (017C) that I don't have documented, so I don't know what it does.
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Rob
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