Diseqc control anyone ?

[HenrikOlsson]

Hi,
Am I correct in that "all it is" a 22kHz carrier modulated 0.5ms ON, 1.0ms OFF for a logic one and 1.0ms ON, 0.5ms ON for logic zero? How critical is the 22kHz and how critical is the on/off times?

Doesn't sound too hard to do with a PIC, much like a IR remote. The CCP moudle can generate a 22kHz tone which you can modulate with software by simply truning the signal on and off. You need external filter and attenutation+buffer to get the 0.65V peak-to-peak sinewave carrier.

With that said, I've got no experience with Diseqc, this is the firts time I've looked at it.

/Henrik.

[mark_s]

I think this PDF has enough information to create a PBP encoder/decoder. Like Henrik said, it looks a lot like IR remote control format. Very low bit rate.

http://www.eutelsat.com/files/contri...s/bus_spec.pdf

[F1CHF]

yes you are right, seems similar to IR protocol
Henri what do you mean bye "The CCP moudle can generate a 22kHz"
there are two options : External 22 Khz generator or if the pic is free, have a process to do that ..
They said "nominal 22 kHz (±20 %)" so a simple NE555 could be OK

I must make a prototype, as I have some Disecq LNB switch to test, I will be able to verify
problem is to fond some more time !
This was the first objective of my first message "already done by somebody" hi ...
Thanks
Francois

[HenrikOlsson]

The CCP module can be setup to generate a 22kHz squarewave. Use an external filter to turn it into a sine and attenutate it 650mV, then use a rail-to-rail OP-Amp to buffer it and (I'm guessing) AC-couple it onto the coax. Then it's just a matter of turning the CCP module on and off with the correct timings to get the signal out.

I don't know, you may be able to just attenuate and AC-couple the square wave directly onto the cable.

Do you have a PIC already that you wanted to use?

[CuriousOne]

Devices like this can be used for this task:

http://www.ebay.com/itm/SatLink-WS-6...0AAOSwc1FXbKjD

Also, as I said, I've generated diseqc commands in sound editor. Then recorded to phone, and built simple circuit to allow it to be transferred to switch.