Emulation Timing Calculations
E-8
Example E–1. Key Timing for a Single-Processor System Without Buffers
t
pd
ǒ
TCK_RET-TMS
ń
TDI
Ǔ
+
ƪ
t
d
ǒ
TMSmax
Ǔ
)
t
su
ǒ
TTMS
Ǔ
ƫ
t
TCKfactor
+
(20 ns
)
10 ns)
0.4
+
75 ns, or 13.3 MHz
t
pd
ǒ
TCK_RET–TDO
Ǔ
+
ƪ
t
d
ǒ
TTDO
Ǔ
)
t
su
ǒ
TDOmin
Ǔ
ƫ
t
TCKfactor
+
(15 ns
)
3 ns)
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
ń
TDI)
+
ƪ
t
d (TMSmax
)
)
t
su (TTMS
)
)
t
bufskew
ƫ
t
TCKfactor
+
(20 ns
)
10 ns
)
1.35 ns)
0.4
+
78.4 ns, or 12.7 MHz
t
pd (TCK_RET–TDO)
+
ƪ
t
d (TTDO
)
)
t
su (TDOmin)
)
t
d (bufmax
)
ƫ
t
TCKfactor
+
70 ns, or 14.3 MHz
+
(15 ns
)
3 ns
)
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.
