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