_______________________________________________________________________ 2 AsteRx3_OEM
AsteRx3 Product Family Hardware Manual v2.5.0
19
2.4
Frequency Reference Selection
The receiver can get its 10-MHz frequency reference from its internal TCXO, or from an external
reference source. The clock selection is controlled by the EXTREF_STAT pin (pin#55), as follows:
EXTREF_STAT pin level Reference clock source
Signal at REF_O pin (pin#39)
Pin left open (there is an
internal pull-up)
Internal TCXO
10-MHz square wave from the
internal TCXO.
Pin tied to ground
REF_I pin (pin#43)
None. Output is disabled.
2.5
Ethernet
There is no isolation transformer in the AsteRx3_OEM.
An examplary 10Baset-T application circuit with isolation transformer is shown below. The four lines
at the left are connected to the pins#73, #75, #77 and #79 of the 80-pin connector. The four lines at
the right can be connected to a RJ-45 plug.
2.6
Stand-By Mode
In stand-by mode, the receiver consumes a fraction of its nominal power.
There are two ways to request the receiver to enter stand-by mode:
1.
by using the command “
exePowerMode
” (see Command Line Interface Reference Guide);
2.
by shortly driving pin#8 (nPOWER_TOGGLE) low as indicated in section 2.3.
After having requested to enter stand-by mode, it takes up to 0.5 seconds for the receiver to actually
enter low-power state. This time is required to unmount the SD memory card and stop all software
activities.
Waking up from stand-by mode is done in one of the following ways:
1.
by sending one or more characters to the first serial port (COM1) at a baud rate lower than
4800baud;
2.
by shortly driving pin#8 (nPOWER_TOGGLE) low.
Note that if the receiver has been set in stand-by mode by the command “
exePowerMode,
ScheduledSleep
”, it will wake up automatically after a prescribed amount of time.
RJ45_TX-
RJ45_RX-
