Table of Contents
Advertisement
Case 2:
Single/multiprocessor, TMS/TDI/TCK buffered input, TDO buffered output,
TMS/TDI timed from TCK_RET low.
t
pd (TCK_RET–TMS TDI)
t
pd (TCK_RET–TDO)
In this case, the TCK_RET-to-TMS/TDI path is the limiting factor.
In a multiprocessor application, it is necessary to ensure that the EMU0–1 lines
can go from a logic low level to a logic high level in less than 10 µs. This can be
calculated as follows:
t
r
t
t
d (TMSmax
su (TTMS
)
+
t
TCKfactor
20ns
10ns
+
0.4
+ 78.4ns (12.7 MHz)
t
t
d (TTDO
su (TDOmin)
)
+
t
TCKfactor
[15ns
3ns
10ns]
+
0.4
+ 70ns (14.3 MHz)
= 5(R
N
pullup
devices
= 5(4.7 k
16 15 pF)
= 5.64 µs
Designing for JTAG Emulation
Emulation Timing Calculations
t
(bufskew)
)
1.35 ns
t
d (bufmax
)
C
)
load_per_device
15-7
Advertisement
Chapters
Table of Contents
