Connections Between the Emulator and the Target System
15-8
15.7 Connections Between the Emulator and the Target System
It is extremely important to provide high-quality signals between the emulator
and the JTAG target system. Depending upon the situation, you must supply
the correct signal buffering, test clock inputs, and multiple processor intercon-
nections to ensure proper emulator and target system operation.
Signals applied to the EMU0 and EMU1 pins on the JTAG target device can
be either input or output (I/O). In general, these two pins are used as both input
and output in multiprocessor systems to handle global run/stop operations.
EMU0 and EMU1 signals are applied only as inputs to the XDS510 emulator
header.
15.7.1 Buffering Signals
If the distance between the emulation header and the JTAG target device is
greater than six inches, the emulation signals must be buffered. If the distance
is less than six inches, no buffering is necessary. The following illustrations
depict these two situations.
-
No signal buffering. In this situation, the distance between the header
and the JTAG target device should be no more than six inches.
VCC
Emulator Header
VCC
GND
12
10
8
6
4
5
GND
GND
GND
GND
GND
PD
TCK_RET
TCK
TDO
TDI
TMS
TRST
EMU1
EMU0
9
11
7
3
1
2
14
13
JTAG Device
TCK
TDO
TDI
TMS
TRST
EMU1
EMU0
6 Inches or Less
The EMU0 and EMU1 signals must have pullup resistors connected to V
CC
to
provide a signal rise time of less than 10
µ
s. A 4.7-k
Ω
resistor is suggested for
most applications.