1.. Permission is granted to copy, distribute and/or modify this
2.. document under the terms of the GNU Free Documentation License,
3.. Version 1.1 or any later version published by the Free Software
4.. Foundation, with no Invariant Sections, no Front-Cover Texts
5.. and no Back-Cover Texts. A copy of the license is included at
6.. Documentation/media/uapi/fdl-appendix.rst.
7..
8.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections
9
10.. _FE_SET_VOLTAGE:
11
12********************
13ioctl FE_SET_VOLTAGE
14********************
15
16Name
17====
18
19FE_SET_VOLTAGE - Allow setting the DC level sent to the antenna subsystem.
20
21
22Synopsis
23========
24
25.. c:function:: int ioctl( int fd, FE_SET_VOLTAGE, enum fe_sec_voltage voltage )
26    :name: FE_SET_VOLTAGE
27
28
29Arguments
30=========
31
32``fd``
33    File descriptor returned by :ref:`open() <frontend_f_open>`.
34
35``voltage``
36    an integer enumered value described at :c:type:`fe_sec_voltage`
37
38
39Description
40===========
41
42This ioctl allows to set the DC voltage level sent through the antenna
43cable to 13V, 18V or off.
44
45Usually, a satellite antenna subsystems require that the digital TV
46device to send a DC voltage to feed power to the LNBf. Depending on the
47LNBf type, the polarization or the intermediate frequency (IF) of the
48LNBf can controlled by the voltage level. Other devices (for example,
49the ones that implement DISEqC and multipoint LNBf's don't need to
50control the voltage level, provided that either 13V or 18V is sent to
51power up the LNBf.
52
53.. attention:: if more than one device is connected to the same antenna,
54   setting a voltage level may interfere on other devices, as they may lose
55   the capability of setting polarization or IF. So, on those cases, setting
56   the voltage to SEC_VOLTAGE_OFF while the device is not is used is
57   recommended.
58
59
60Return Value
61============
62
63On success 0 is returned.
64
65On error -1 is returned, and the ``errno`` variable is set
66appropriately.
67
68Generic error codes are described at the
69:ref:`Generic Error Codes <gen-errors>` chapter.
70