.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
|
.. c:namespace:: DTV.fe
|
|
.. _FE_SET_VOLTAGE:
|
|
********************
|
ioctl FE_SET_VOLTAGE
|
********************
|
|
Name
|
====
|
|
FE_SET_VOLTAGE - Allow setting the DC level sent to the antenna subsystem.
|
|
Synopsis
|
========
|
|
.. c:macro:: FE_SET_VOLTAGE
|
|
``int ioctl(int fd, FE_SET_VOLTAGE, enum fe_sec_voltage voltage)``
|
|
Arguments
|
=========
|
|
``fd``
|
File descriptor returned by :c:func:`open()`.
|
|
``voltage``
|
an integer enumered value described at :c:type:`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.
|
|
.. attention:: 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 is returned, and the ``errno`` variable is set
|
appropriately.
|
|
Generic error codes are described at the
|
:ref:`Generic Error Codes <gen-errors>` chapter.
|
