OPERATION
Copyright 2007
5-17
S SC150e HARDWARE REFERENCE
5.9 External Triggers
NOTE
: User access to external triggers is not available on the PMC card.
The S SC150e Network provides two external triggers. The external triggers
will occur only if the ACR has been configured to enable them. Triggers 1 and 2 are
generated by S SC150e shared-memory access. Triggers generate a 26.64 ns
TTL level compatible, non-terminated, output.
•
Trigger 1 - Host Write (ACR[2] enables)
•
Trigger 2 - Network Write (ACR[3] enables)
Trigger 1 will be generated for any host write to S SC150e memory.
Trigger 2 will be generated by a network write to the S SC150e memory.
Pin 7 of the Auxiliary Connector is connected to TRIG1 logically OR’ed with TRIG2.
The triggers can be used to measure time intervals or to start or stop an external event.
EXAMPLE 1 - MEASURE TRANSACTION TIME
To measure transaction time, perform the following steps:
1.
Select a shared-memory address in node A and enable trigger 1 by setting
ACR[2] and not ACR[3].
2.
Select the same memory address in node B and enable trigger 2 by setting
ACR[3] and not ACR[2].
3.
Connect a wire from TRIG1 to an oscilloscope.
4.
Connect a wire from TRIG2 to the oscilloscope.
5.
Initiate a HOST write to the node A memory address.
When the corresponding NETWORK write occurs, the time difference can be measured.
EXAMPLE 2 - MEASURE RING TIME
To measure ring time, the time it takes from the HOST write on node A to the
NETWORK write on node A, perform the following steps:
1.
Enable WRITE-ME-LAST mode on node A.
2.
Select a shared-memory address and enable trigger 1 and trigger 2 for that
address.
3.
Connect a wire from TRIG (pin 7 of the Auxiliary Connector (see section 4.7) to
an oscilloscope.
4.
Initiate a HOST write to that memory address.
The time difference displayed on the oscilloscope will approximate the ring time.
EXAMPLE 3 - SET OFF AN ALARM
To set off an alarm, perform the following steps:
1.
Enable trigger 1 for the shared-memory address of a critical datum by setting
ACR[2] and not ACR[3].
2.
Connect a wire from TRIG1 to an alarm light.
When the HOST write to that memory address occurs, the light will come on.
Summary of Contents for SCRAMNet+ SC150e
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