Actel Silicon Explorer II, User Manual, Page: 38 / 42

Appendix D: Troubleshooting
32
Software Setup
Q: How do I set up triggering?
A: You have an option of setting trigger either EARLY that displays
the values in the ratio of (25% 75%), where the first % represents
the % of data sampled before the trigger point and the later %
represent % sampled after the trigger point. The other options
available are CENTER(50% 50%) and LATE(75% 25%). You can
select the trigger position from Instrument -> Trigger Position and
then selecting the required Trigger position.
Q: What is the recommended sampling rate?
A: For an accurate reading, the sampling rate for a particular signal
should be at least twice the rate at which the signal is changing
(According to the Nyquist theorem). For example, a clock
operating at 25MHz should be sampled at least 50MHz frequency.
Sampling at higher frequencies however causes the Silicon
Explorer to consume more power.
Q: What is the best way to find nets?
A: The best way to find the nets in the Silicon Explorer is to use the
Filter option available in the software. You can search for the net
you require by using the *partial_name* in the filter, which would
return all the signals having that partial_name of the net. If you are
using an HDL flow, it may be difficult to recognize the net names
you need to observe. We recommend that you use a synthesis tool
that can generate a gate-level schematic of your synthesized netlist
so that during probing, you can easily trace through the schematic
and obtain the net names from it.
Hardware Setup
Q: How do I probe an SX-A device?
A: The probing of an SXA device requires special setup because it
requires a 70 ohm termination on all the probe connectors (TDI,
TDO, TCK, TMS, PRA, PRB). The 70 ohm series termination is used
to prevent data transmission corruption during probing.