23
23
Pinout and I/O Description
23
sufficiently low to avoid excessive level drop because of the filtering of the divider
with the input capacitance of the REF_I input (8 pF). Below an example circuit. The
module has a build-in DC-decoupling capacitor.
Support for an external frequency reference is not available in all mosaic models. It is only
available on those models where the FreqSync permission is enabled. Using an external
reference without corresponding permission will cause the module to block most SBF
output.
4.8
Event/TimeSync inputs
The module features two event inputs, which can be used to time tag external events with
a time resolution of 20ns.
Pin Name
Type
Level
Description
Comment
EVENTA
I, PD
1V8_LVTTL
Event A or TimeSync input. The pull-down is about 200 kOhm.
Leave unconnected if not used
EVENTB
I, PD
1V8_LVTTL
Event B or TimeSync input. The pull-down is about 200 kOhm.
Leave unconnected if not used
Use the
setEventParameters
user command to configure the EVENTx pins (e.g. to set the
polarity). Note that this feature is not available on all mosaic models. It requires the
TimedEvent permission to be enabled. For correct detection, the minimum time between
two events on the same EVENTx pin must be at least 5ms, and there must be no more
than 20 events in any interval of 100ms, all EVENTx pins considered.
If the TimeSync permission is enabled in your mosaic model, the event inputs can also be
configured as TimeSync source using the
setTimeSyncSource
command. When an event
pin is configured as TimeSync source, the mosaic module expects to see a one-pulse-per-
second (1PPS) signal on that pin. It will then synchronize its internal time base (i.e. the
time at which GNSS measurements are sampled) to that 1PPS signal. TimeSync is typically
used in conjunction with ExtFreq (see section 4.7.2) to fully synchronize the module
internal time base with the time of an external clock.
Note that there is a delay of 15 to 50 ns between the PPS pulse at the EVENT pin and the
module internal time base. That delay is dependent on the phase difference between the
10 MHz frequency at the REF_I pin and the PPS pulse at the EVENT pin. It is possible to
measure this delay by synchronizing the PPS OUT pulse with the internal time base, with
the
setPPSParameters,,,,RxClock
command.
