Spectrum Brands MC.31XX - Manual (Page 10)

10 MC.31xx Manual
Additional options Introduction
Starhub
The star hub module allows the synchronisation of up to 16 MC boards. It is possible
to synchronise boards of the same type with each other as well as different types.
The module acts as a star hub for clock and trigger signals. Each board is connected
with a small cable of the same length, even the master board. That minimises the clock
skew between the different boards. The figure shows the piggyback module mounted
on the base board schematically without any cables to achieve a better visibility.
Any board could be the clock master and the same or any other board could be the
trigger master. All trigger modes that are available on the master board are also avail-
able if the synchronisation star hub is used.
The cable connection of the boards is automatically recognised and checked by the
driver at load time. So no care must be taken on how to cable the boards. The pro-
gramming of the star hub is included in the standard board interface and consists of
only 3 additional commands.
It is not possible to use this option together with the timestamp or extra
I/O option, because the is just space for one piggyback module on the
on-board expansion slot.
Timestamp
The timestamp module was designed to record the exact time information between trig-
ger events.
The timestamp reset command sets an internal counter to zero. The counter is running
with the same resolution as the sample rate. On each trigger event a timestamp is re-
corded in an extra FIFO. The recorded timestamps are read out asynchronously to the
board sampling.
If the absolute time information is of interest it is possible to synchronise the timestamp
counter with a 1 Hz "seconds" signal of a radio clock or a GPS receiver. In that case
the 64 bit timestamp information is split up in two parts. The one part counts the
number of seconds starting with the reset command, the other part is set to zero on
every rising edge of the seconds signal and specifies the exact time position in relation
to the seconds signal.
The figure shows the piggyback module installed on the on-board expansion slot. The
shown option is mounted exemplarily on a board with two modules.
It is not possible to use this option together with the star hub or extra
I/O option, because the is just space for one piggyback module on the
on-board expansion slot.