Texas Instruments TMDSEMU560V2STM-U - Blackhawk XDS560v2 System Trace USB Emulator TMDSEMU560V2STM-U TMDSEMU560V2STM-U Datenbogen
Produktcode
TMDSEMU560V2STM-U
Connections Between the Emulator and the Target System
3-14
3.7.2
Using a Target-System Clock
Figure 3−6 shows an application with the system test clock generated in the
target system. In this application, the TCK signal is left unconnected.
target system. In this application, the TCK signal is left unconnected.
Figure 3−6. Target System Generated Test Clock
EMU0
EMU1
EMU1
TRST
TMS
TDI
TDO
TCK
TCK_RET
TVD
GND
GND
GND
GND
GND
GND
GND
GND
GND
13
14
14
1
2
9
11
7
3
Emulation header
VCC I/O
VCC I/O
EMU0
EMU1
TRST
TMS
TDI
TDO
TCK
EMU1
TRST
TMS
TDI
TDO
TCK
Target device
Greater than 6 inches
5
4
6
8
6
8
10
12
12
System test
clock
Note:
When the TMS/TDI lines are buffered, pullup resistors should be used to hold the buffer inputs at a known level when the
emulator cable is not connected.
emulator cable is not connected.
A benefit to having the target system generate the test clock, there may be oth-
er devices in your system that require a test clock when the emulator is not con-
nected. The system test clock also serves this purpose.
er devices in your system that require a test clock when the emulator is not con-
nected. The system test clock also serves this purpose.
3.7.3
Configuring Multiple Processors
Figure 3−7 shows a typical series linked multiprocessor configuration, which
meets the minimum requirements of the IEEE 1149.1 standard. The emulation
signals in this example are buffer to isolate the processor from the emulation
and provide adequate signal drive for the target system. One of the benefits
of this type of interface is that you can generally slow down the test clock to
eliminate timing problems. Use the following guidelines for multiprocessor
support:
meets the minimum requirements of the IEEE 1149.1 standard. The emulation
signals in this example are buffer to isolate the processor from the emulation
and provide adequate signal drive for the target system. One of the benefits
of this type of interface is that you can generally slow down the test clock to
eliminate timing problems. Use the following guidelines for multiprocessor
support:
-
The processor TMS, TDI, TDO, and TCK signals should be buffered
through the same physical package for better control of timing skew.
through the same physical package for better control of timing skew.
-
The input buffers of TMS, TDI, and TCK should have pull-up resistors con-
nected to V
nected to V
CC
I/O to hold these signals at a known value when the emula-
tor is not connected. A resistor value of 4.7 k
Ω
or greater is suggested.