Systran SCRAMNet+ VME3U, Hardware Reference Manual

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HOST ACCESS TIMING
Copyright 1995, S
YS
I
RAN
Corp. D-3 VME3U H/W REFERENCE
DTACK*
AS*
DSx*
HREQ
HACK
1
5
3
4
2
1. AS to DSx = 10 ns (per VME Spec.)
2. DSx to HREQ = 80 ns (Host Adapter time)
3. HREQ = 53 ns (Host Adapter time)
4. End of HREQ to HACK = 106 ns (DPRC thru HACK = 133 ns)
5. HACK to DTACK = 22 ns (Host Interface)
6. DTACK to End of Cycle = 0 ns (per VME Spec.) 271 ns
Figure D-2 READ From Internal CSR
D.3.2 ASIC-Internal CSR WRITE
This is a typical WRITE cycle of an ASIC-internal CSR:
•
AS and DS fall
•
HREQ requested for a particular CSR (address)
•
Data accepted and ASIC asserts HACK
•
Assert DTACK
•
Requester (Master/CPU) de-asserts AS and DS (end of cycle)
Figure D-3 is an example of a WRITE to an internal CSR.
DTACK*
AS*
DSx*
HREQ
HACK
1
3
2
1. AS to DSx = 10 ns (per VME Spec.)
2. DSx to HREQ = 106 ns (Host Adapter time)
3. HREQ to DTACK = 53 ns (Host Interface)
4. DTACK to End of Cycle = 0 ns (per VME spec) 169 ns
Figure D-3 WRITE to Internal CSR