[deliverable/linux.git] / Documentation / linux_tv / media / dvb / fe-set-voltage.rst

.. -*- coding: utf-8; mode: rst -*-

.. _FE_SET_VOLTAGE:

********************
ioctl FE_SET_VOLTAGE
********************

NAME
====

FE_SET_VOLTAGE - Allow setting the DC level sent to the antenna subsystem.

SYNOPSIS
========

.. c:function:: int ioctl( int fd, int request, enum fe_sec_voltage *voltage )


ARGUMENTS
=========

``fd``
    File descriptor returned by :ref:`open() <frontend_f_open>`.

``request``
    FE_SET_VOLTAGE

``voltage``
    pointer to enum :ref:`fe_sec_voltage <fe-sec-voltage>`

    Valid values are described at enum
    :ref:`fe_sec_voltage <fe-sec-voltage>`.


DESCRIPTION
===========

This ioctl allows to set the DC voltage level sent through the antenna
cable to 13V, 18V or off.

Usually, a satellite antenna subsystems require that the digital TV
device to send a DC voltage to feed power to the LNBf. Depending on the
LNBf type, the polarization or the intermediate frequency (IF) of the
LNBf can controlled by the voltage level. Other devices (for example,
the ones that implement DISEqC and multipoint LNBf's don't need to
control the voltage level, provided that either 13V or 18V is sent to
power up the LNBf.

NOTE: if more than one device is connected to the same antenna, setting
a voltage level may interfere on other devices, as they may lose the
capability of setting polarization or IF. So, on those cases, setting
the voltage to SEC_VOLTAGE_OFF while the device is not is used is
recommended.


RETURN VALUE
============

On success 0 is returned, on error -1 and the ``errno`` variable is set
appropriately. The generic error codes are described at the
:ref:`Generic Error Codes <gen-errors>` chapter.
Commit	Line	Data
5377d91f MH	1	.. -- coding: utf-8; mode: rst --
	2
	3	.. _FE_SET_VOLTAGE:
	4
	5	********************
	6	ioctl FE_SET_VOLTAGE
	7	********************
	8
586027ce MCC	9	NAME
586027ce MCC	10	====
5377d91f	11
586027ce	12	FE_SET_VOLTAGE - Allow setting the DC level sent to the antenna subsystem.
5377d91f	13
586027ce	14	SYNOPSIS
5377d91f MH	15	========
	16
	17	.. c:function:: int ioctl( int fd, int request, enum fe_sec_voltage *voltage )
	18
586027ce MCC	19
586027ce MCC	20	ARGUMENTS
5377d91f MH	21	=========
	22
	23	``fd``
	24	File descriptor returned by :ref:`open() <frontend_f_open>`.
	25
	26	``request``
	27	FE_SET_VOLTAGE
	28
	29	``voltage``
	30	pointer to enum :ref:`fe_sec_voltage <fe-sec-voltage>`
	31
	32	Valid values are described at enum
	33	:ref:`fe_sec_voltage <fe-sec-voltage>`.
	34
	35
586027ce	36	DESCRIPTION
5377d91f MH	37	===========
	38
	39	This ioctl allows to set the DC voltage level sent through the antenna
	40	cable to 13V, 18V or off.
	41
	42	Usually, a satellite antenna subsystems require that the digital TV
	43	device to send a DC voltage to feed power to the LNBf. Depending on the
	44	LNBf type, the polarization or the intermediate frequency (IF) of the
	45	LNBf can controlled by the voltage level. Other devices (for example,
	46	the ones that implement DISEqC and multipoint LNBf's don't need to
	47	control the voltage level, provided that either 13V or 18V is sent to
	48	power up the LNBf.
	49
	50	NOTE: if more than one device is connected to the same antenna, setting
	51	a voltage level may interfere on other devices, as they may lose the
	52	capability of setting polarization or IF. So, on those cases, setting
	53	the voltage to SEC_VOLTAGE_OFF while the device is not is used is
	54	recommended.
	55
586027ce	56
5377d91f	57	RETURN VALUE
586027ce	58	============
5377d91f MH	59
	60	On success 0 is returned, on error -1 and the ``errno`` variable is set
	61	appropriately. The generic error codes are described at the
	62	:ref:`Generic Error Codes <gen-errors>` chapter.