ARM
Processor/ASIC
JTAG
CONNECTOR
ARM
Processor/ASIC
TDI
TMS
TCK
TDO
TDI
TMS
TCK
TDO
Figure 2-11 JTAG connection with de-skewed buffers
This solution matches the skew between TDI/TMS and TCK signals to achieve very high JTAG
frequencies. By feeding TMS through separate resistors for each target device, termination of each signal
is achieved without incurring the cost of extra buffers. All termination resistors should be placed as close
as possible to the buffers.
Note
• For added noise rejection, Schmitt buffers may be used instead of standard buffers.
• Buffers with a drive strength of 24mA or above are recommended.
For guidance on selection of series termination resistors, see 2.9 Series termination on page 2-37.
2 ARM
®
DSTREAM-ST target interface connections
2.6 About JTAG port buffering
ARM 100893_0100_00_en Copyright © 2017 ARM Limited or its affiliates. All rights reserved. 2-33
Non-Confidential
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