[linux-dvb] Re: Full featured card summary

[Holger Waechtler <holger@qanu.de>]

On Sunday 14 March 2004 23:46, Andrew de Quincey wrote:
> On Sunday 14 March 2004 22:36, Holger Waechtler wrote:
> >
> > As soon you submit the polarisation selection command (VOLTAGE_13V or
> > VOLTAGE_18V) you already powered up the LNB. The only important thing is
> > to maintain the delay times required by the spec, the diseqc.c example
> > shows how this can get implemented.
>
> I think the problem was they're using DISEQC 1.0/2.0 switches, but weren't
> using the older voltage-based polarisation selection commands, assuming
> that the frontend would have automatically applied some power to the LNB
> (BTW: I do know the sequence in the DISEQC spec says you should specify the
> voltage; I use that exact sequence in my code).

The DiSEqC spec explicitly requires you to set up a bus voltage of 13 or 18V 
and wait a little before submitting any command.

> I suppose its a matter of how tolerant we want to be of userspace
> programs.. I mean, we already turn OFF the LNB power automatically, why not
> turn it on as well?

we do, a LNB power switch is automatically enabled as soon a voltage != 0V is 
specified by all drivers I'm aware of. Did not checked the latest changes 
though, if the VES1x93 does not do so anymore it needs to get fixed, you 
should set the GPIO line high that is connected to the LNBP as soon any bus 
voltage != 0V is requested.

Holger


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