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Emulation Timing Calculations
E-8
Example E–1. Key Timing for a Single-Processor System Without Buffers
t
pd TCK_RET-TMS TDI
t
d TMSmax
t
su TTMS
t
TCKfactor
(
20 ns 10 ns
)
0.4
75 ns, or 13.3 MHz
t
pd TCK_RET–TDO
t
d TTDO
t
su TDOmin
t
TCKfactor
(
15 ns 3ns
)
0.4
45 ns, or 22.2 MHz
In this case, because the TCK_RET-to-TMS/TDI path requires more time to
complete, it is the limiting factor.
Example E–2. Key Timing for a Single- or Multiple-Processor System With Buffered Input
and Output
t
pd(TCK_RET-TMS TDI)
t
d(TMSmax)
t
su(TTMS)
t
bufskew
t
TCKfactor
(
20 ns 10 ns 1.35 ns
)
0.4
78.4 ns, or 12.7 MHz
t
pd(TCK_RET–TDO)
t
d(TTDO)
t
su (TDOmin)
t
d(bufmax)
t
TCKfactor
70 ns, or 14.3 MHz
(
15 ns 3ns 10 ns
)
0.4
In this case also, because the TCK_RET-to-TMS/TDI path requires more time
to complete, it is the limiting factor.