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Topic:
convert 'long hex' from makehex to short hex code (like LIRC)
This thread has 3 replies. Displaying all posts.
Post 1 made on Monday August 30, 2010 at 15:15
thebeast
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I feel that this topic will make people groan because i get the impression it comes up a bit but I really have tried to sort this out and I can't find the answer. The problem is this:
I've got a long hex code (pasted below) that I know from others' posts is the discrete code for 'ext 1' for my Samsung TV. Trouble is that the system I use (an arduino chip programmed to control an IR led) needs to know the 'short' hex code - like the ones used by LIRC. (For example the 'toggle power' is E0E040BF). Can anyone help me with how to convert from the long code below to a short code like that?

Thanks,
Ben

Code:
0000 006D 0000 0022 00AC 00AB 0015 0041 0015 0041 0015 0041 0015 0016 0015 0016 0015 0016 0015 0016 0015 0016 0015 0041 0015 0041 0015 0041 0015 0016 0015 0016 0015 0016 0015 0016 0015 0016 0015 0016 0015 0016 0015 0041 0015 0016 0015 0016 0015 0016 0015 0016 0015 0041 0015 0041 0015 0041 0015 0016 0015 0041 0015 0041 0015 0041 0015 0041 0015 0016 0015 0689
Post 2 made on Monday August 30, 2010 at 18:29
3FG
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Here's one way: Download IRTool.exe , and paste the Pronto Hex format into it.  Click Decode Hex.

Power Toggle in Pronto Hex format is:
0000 006d 0022 0003 00a9 00a8 0015 003f 0015 003f 0015 003f 0015 0015 0015 0015 0015 0015 0015 0015 0015 0015 0015 003f 0015 003f 0015 003f 0015 0015 0015 0015 0015 0015 0015 0015 0015 0015 0015 0015 0015 003f 0015 0015 0015 0015 0015 0015 0015 0015 0015 0015 0015 0015 0015 0040 0015 0015 0015 003f 0015 003f 0015 003f 0015 003f 0015 003f 0015 003f 0015 0702 00a9 00a8 0015 0015 0015 0e6e
These numbers are mostly time durations of on and off.

IRTool decodes the numbers as Device =7.7  and OBC (function code) = 2.  Ignore the EFC number.  The IR protocol is NECx2.

Using the DecodeIR.html document in the IRTool distribution, we see that NECx2 is arranged as Device.device+Function code+ complement of the function code  (see the "D:8,D:8,F:8,~F8" in the IRP notation?).  The next thing to understand is that LIRC sends the bits in reversed order to the way device and function numbers are expressed in IRTool.

So device 7 is
0000 0111    0x07  (Hexadecimal notation)
1110 0000    0xE0  (bit order reversed)

Function 2 is
0000 0010    0x02
0100 0000    0x40 (bit order reversed)
1011 1111    0xBF (complemented)

So D:D:F:~F is
E0E040BF    (This is the converted code)

The LIRC executor will convert these device and function numbers into durations according to the first part of the IRP specification "38.4k,564}<1,-1|1,-3>".   Of course other IR protocols will require a different procedure.
OP | Post 3 made on Tuesday August 31, 2010 at 08:59
thebeast
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Thank you very much, 3FG I shall give it a whirl. Ben
Post 4 made on Tuesday August 31, 2010 at 09:31
Duct Tape
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 cool, that is a great explanation for dummies like me :)
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