0001 .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
0002 .. c:namespace:: DTV.fe
0003
0004 .. _FE_SET_VOLTAGE:
0005
0006 ********************
0007 ioctl FE_SET_VOLTAGE
0008 ********************
0009
0010 Name
0011 ====
0012
0013 FE_SET_VOLTAGE - Allow setting the DC level sent to the antenna subsystem.
0014
0015 Synopsis
0016 ========
0017
0018 .. c:macro:: FE_SET_VOLTAGE
0019
0020 ``int ioctl(int fd, FE_SET_VOLTAGE, enum fe_sec_voltage voltage)``
0021
0022 Arguments
0023 =========
0024
0025 ``fd``
0026 File descriptor returned by :c:func:`open()`.
0027
0028 ``voltage``
0029 an integer enumered value described at :c:type:`fe_sec_voltage`
0030
0031 Description
0032 ===========
0033
0034 This ioctl allows to set the DC voltage level sent through the antenna
0035 cable to 13V, 18V or off.
0036
0037 Usually, a satellite antenna subsystems require that the digital TV
0038 device to send a DC voltage to feed power to the LNBf. Depending on the
0039 LNBf type, the polarization or the intermediate frequency (IF) of the
0040 LNBf can controlled by the voltage level. Other devices (for example,
0041 the ones that implement DISEqC and multipoint LNBf's don't need to
0042 control the voltage level, provided that either 13V or 18V is sent to
0043 power up the LNBf.
0044
0045 .. attention:: if more than one device is connected to the same antenna,
0046 setting a voltage level may interfere on other devices, as they may lose
0047 the capability of setting polarization or IF. So, on those cases, setting
0048 the voltage to SEC_VOLTAGE_OFF while the device is not is used is
0049 recommended.
0050
0051 Return Value
0052 ============
0053
0054 On success 0 is returned.
0055
0056 On error -1 is returned, and the ``errno`` variable is set
0057 appropriately.
0058
0059 Generic error codes are described at the
0060 :ref:`Generic Error Codes <gen-errors>` chapter.
