Spectrum Brands MI.20xx - Manual (Page 9)

Introduction Additional options
(c) Spectrum GmbH 9
Starhub
The star hub module allows the syn-
chronisation of up to 16 MI 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 ca-
ble of the same length, even the ma-
ster board. That minimises the clock
skew between the different boards.
The figure shows the piggyback mo-
dule mounted on the base board
schematically without any cables to
achieve a better visibility.
Any board could be the clock ma-
ster and the same or any other
board could be the trigger master. All trigger modes that are available on the master board are also available 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 programming 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 desi-
gned to record the exact time infor-
mation between trigger events.
The timestamp reset command sets
an internal counter to zero. The
counter is running with the same re-
solution as the sample rate. On each
trigger event a timestamp is recor-
ded in an extra FIFO. The recorded
timestamps are read out asynchro-
nously 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.