after having a look at this page:
http://zovirl.com/2008/11/12/building-a-universal-remote-with-an-arduino/
I couldn't figure out something, the person who wrote the article came up with those 5 codes:
fade up = [255, 136, 130, 34]
fade down = [255, 136, 130, 20]
full on = [255, 136, 132, 184]
full off = [255, 136, 189, 18]
memory recall = [255, 136, 132, 183]
how did he come with those numbers just by looking at what the oscilloscope shown?
and is it possible to come up with those codes for my remote control without an oscilloscope?
thanks
how did he come with those numbers just by looking at what the oscilloscope shown
The clue is in the words of the article, he says:-
To decode what the remote was sending, I used an oscilloscope and a small photodiode. ..... I have a Parallax USB oscilloscope, which is perfect for showing the command pulses and is just fast enough to find the modulation frequency.
The trace you see gives you the numbers:-
The lengths of the on/off pulses are all multiples of 2.3 milliseconds (which means that the entire 82.8 ms command represents 36 bits of data).
The last four bits are always 0, so really each command is four bytes long, followed by four 0 bits
Each command is made up of 36 bits each bit signifies the length of the on part of the pulse. If it is long it is a 1 and if it is short it is a zero. When you have all 36 zeros and ones, you split them up into 8 bit bytes and write the number according to what the value of the byte is.
is it possible to come up with those codes for my remote control without an oscilloscope?
not really but you can make an oscilloscope with with an Arduino. There are lots of examples on the net, this is just one.
http://arduino.cc/blog/?p=62
thank you for this info, but there is something that i still haven't got the answer to.
now that i know that he splitted the 36 bits into 4 sections. the bits are (after converting to binary):
1111-1111,1000-1000,1000-0010,0010-0010,0000
how did the author know when to add 1's and 0's? did he do it only by looking at the picture the oscilloscope gave?
for example, when i see the first 8 bits of 1 i cant really tell they are exactly 8.
did he do it only by looking at the picture the oscilloscope gave?
Yes.
i cant really tell they are exactly 8.
You can from the time they are high. You know the bit time from looking at the time of the shortest bit you can find.
There are also programs that will turn a PC sound card into a very limited oscilloscope.
Probably not good enough to definitively measure the frequency at which the IR is being modulated, but likely sufficient to display the demodulated data stream so you can examine and decode it.
Ran