[linux-dvb] Re: Full featured card summary

[Holger Waechtler <holger@qanu.de>]

On Sunday 14 March 2004 23:45, Klaus Schmidinger wrote:
> 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.
>
> 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.

The DiSEqC spec requires you to set the appropriate bus voltage before a 
DiSEqC command is sent. It also requires that the old-style SEC and DiSEqC 
commands are sent compatibly, the behaviour of switches, rotors and LNBs is 
not defined if the content of SEC and DiSEqC sequence don't match. The SEC 
sequence is mandatory (Voltage, tone and burst). See the DiSEqC Update and 
Recommendations for Implementations on the Eutelsat website: 
http://www.eutelsat.org/satellites/pdf/Diseqc/associated 
docs/update_recomm_for_implim.pdf, page 36.

Also check out dvb-apps/test/diseqc.c for a reference implementation.

Holger


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