Jcd,


I am not sure this is a very good learning example, since you would really need to know a lot about what the Sharp protocol looks like in the first place to decode it. Here is an explanation.

DO_PUSH posted a link to an article by Barry Gordon on how to decode Pronto hex and that gives a basic explantion of IR commands.


Barry also wrote a hex generator called GenIRDB [Link: remotecentral.com] , that has a more comprehensive explanation of protocol files and a built in library of a number of protocols including Sharp.

The Sharp protocol file is:
******************************************
Protocol=Sharp
Frequency=37917
Time Base=264
Zero=1,-3
One=1,-7
Form=D:5,F:8,1:2,[1 -165],D:5,~F:8,2:2,[1 -165]
*******************************************


The "Form=D:5,F:8,1:2,[1 -165],D:5,~F:8,2:2,[1 -165]" is the most important statement to look at for decoding.

D:5,F:8,1:2 means device expressed in 5-bits, function expressed in 8-bits, and decimal 1 expressed in 2-bits. Sharp, like most IR commands, has the bits sent Least Significant Bit first and that is backwards to how we usually think of them.

Posted above numeral 1 is:

171(TV)10000100000001001101

that is with spaces between bytes:

DEV Function 1:2 hex
10000 10000000 10 01 1 01

or in proper order:

00001 00000001 01 ==> device=decimal 1, function=decimal 1, and 1:2

The rest of the line seems to be two hex bytes for device and function seperated by a 1.

The actual hex command must be generated with GenIRDB or MakeHex (that shares almost identical protocol files). Since in this case there are an additional 15 data bits that must be appended to the first fifteen described above. In the second 15 bits however ~F means function complement. In the case of F=binary 00000001 then ~F=binary 11111110.

Obviously, you will probably need to read Barry's documentation to really understand this explanation.