1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
2
3.. _FE_SET_VOLTAGE:
4
5********************
6ioctl FE_SET_VOLTAGE
7********************
8
9Name
10====
11
12FE_SET_VOLTAGE - Allow setting the DC level sent to the antenna subsystem.
13
14
15Synopsis
16========
17
18.. c:function:: int ioctl( int fd, FE_SET_VOLTAGE, enum fe_sec_voltage voltage )
19    :name: FE_SET_VOLTAGE
20
21
22Arguments
23=========
24
25``fd``
26    File descriptor returned by :ref:`open() <frontend_f_open>`.
27
28``voltage``
29    an integer enumered value described at :c:type:`fe_sec_voltage`
30
31
32Description
33===========
34
35This ioctl allows to set the DC voltage level sent through the antenna
36cable to 13V, 18V or off.
37
38Usually, a satellite antenna subsystems require that the digital TV
39device to send a DC voltage to feed power to the LNBf. Depending on the
40LNBf type, the polarization or the intermediate frequency (IF) of the
41LNBf can controlled by the voltage level. Other devices (for example,
42the ones that implement DISEqC and multipoint LNBf's don't need to
43control the voltage level, provided that either 13V or 18V is sent to
44power up the LNBf.
45
46.. attention:: if more than one device is connected to the same antenna,
47   setting a voltage level may interfere on other devices, as they may lose
48   the capability of setting polarization or IF. So, on those cases, setting
49   the voltage to SEC_VOLTAGE_OFF while the device is not is used is
50   recommended.
51
52
53Return Value
54============
55
56On success 0 is returned.
57
58On error -1 is returned, and the ``errno`` variable is set
59appropriately.
60
61Generic error codes are described at the
62:ref:`Generic Error Codes <gen-errors>` chapter.
63