[linux-dvb] Re: Full featured card summary

[Klaus Schmidinger <Klaus.Schmidinger@cadsoft.de>]

Holger Waechtler wrote:
> 
> On Sunday 14 March 2004 23:35, Andrew de Quincey wrote:
> > >
> > > If you specify a bus voltage of 13 or 18V you definitely don't mean
> > > VOLTAGE_OFF but expect the LNBP working, everything else is a bug.
> >
> > Yeah, it seemed to have changed from being set to VOLTAGE_13 in the
> > initialisation tables to being set to VOLTAGE_OFF by default... somewhere
> > between the 1.0.1 and the 1.1.0 release.
> >
> > Defaulting to VOLTAGE_OFF makes sense though; no point powering up the LNB
> > until its actually needed. What do you think of Johannes' idea of it auto
> > powering up on frontend open?
> 
> makes not really sense -- you can't really tune a LNB wothout setting up
> polarisation plane and the band selection switch before, can't you?
> 
> 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.

With the DVB driver I am able to use a VDR DiSEqC setup like

S19.2E  11700 V  9750  [E0 10 38 F0] W100 [E0 10 38 F0]
S19.2E  99999 V 10600  [E0 10 38 F1] W100 [E0 10 38 F1]
S19.2E  11700 H  9750  [E0 10 38 F2] W100 [E0 10 38 F2]
S19.2E  99999 H 10600  [E0 10 38 F3] W100 [E0 10 38 F3]

here the sequence [E0 10 38 F0] is sent, followed by a 100ms wait,
and then [E0 10 38 F0] is repeated because the multiswitch is behind
a DiSEqC relay. There's no need for explicit tone or voltage switching
here. So I would say that activating the power supply to the LNB should
be done automatically when the frontend is opened.

As a workaround in VDR 1.3.6 I have added a call to

  ioctl(fd_frontend, FE_SET_VOLTAGE, SEC_VOLTAGE_13)

when opening the device, but I think this shouldn't be necessary.

Klaus


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