John, as always I learn something your posts. I just assumed the Learning/PENG had some serious flaws and never considered your explanation. A few technical corrections but this in no way makes your explanation invalid.
On 08/06/04 10:14, johnsfine said...
the two 18-pair sequences differ only in the 12'th
pair.
Actually the 11th and 12th pair differ. The 11th is a check nibble and the 12th is 8 in the second segment and 0 in the first, the 11th will depend on the other variable bytes. Here would be the entire sequence to compare:
0F 0F 44 1A 0C 00 31 00
0F 0F 44 1A 04 80 31 00
I notice that in addition to rearranging from
AB CAb into ABC AbC, Jon also increased the last
duration in b a little (changed a 41 to a 47).
I'll explain the calculation for sdroog's benefit. After the first four hex words, the remaining hex words represent alternating On and Off times expressed in wavelengths of the IR carrier frequency. In this case 0008 is always the On portion and the Off portion can be one of 16 values so every burst pair represents 4 bits or a nibble of hex. The formula is:
752+Y*135 = Off Burst length in uS (where Y can be 0 to 15)
In this case we want the value of 8 so,
752+8*135 = 1832
1832/25.9 = ~71 decimal =>0x 0047
Where, 25.9 is the wavelength in uS and derived from the second word 006C:
W/L=108*.24=25.9 (006C=>108 dec and .24 is a constant used in ProntoNG commands)
My best guess is that the IR transmitting firmware
is so slow in the NG Prontos, that it adds some
extra duration on the repeat boundary.
I agree and with a delta of only 135 uS representing a change in value, then it's unlikely that it responds that quickly.
