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UM10360_0
© NXP B.V. 2009. All rights reserved.
User manual
Rev. 00.06 — 5 June 2009
611 of 808
NXP Semiconductors
UM10360
Chapter 33: LPC17xx JTAG, Serial Wire Debug, and Trace
5.
Debug Notes
Important:
The user should be aware of certain limitations during debugging. The most
important is that, due to limitations of the Cortex-M3 integration, the LPC17xx cannot
wake up in the usual manner from Deep Sleep and Power-down modes. It is
recommended not to use these modes during debug.
Table 581. JTAG pin description
Pin Name
Type
Description
TCK
Input
JTAG Test Clock.
This pin is the clock for debug logic when in the
JTAG debug mode.
TMS
Input
JTAG Test Mode Select.
The TMS pin selects the next state in the
TAP state machine.
TDI
Input
JTAG Test Data In.
This is the serial data input for the shift register.
TDO
Output
JTAG Test Data Output.
This is the serial data output from the shift
register. Data is shifted out of the device on the negative edge of the
TCK signal.
TRST
Input
JTAG Test Reset.
The TRST pin can be used to reset the test logic
within the debug logic.
RTCK
Output
JTAG Returned Test Clock.
This is an extra signal added to the
JTAG port, and is included for backward pin compatibility with
LPC23xx series devices that share the same pinout as this device.
RTCK is not normally used with the Cortex-M3.
For designs based on ARM7TDMI-S processor core, this signal
could be used by external JTAG host interface logic to maintain
synchronization with targets having a slow or varying clock
frequency. For details refer to "Multi-ICE System Design
considerations Application Note 72 (ARM DAI 0072A)".
Table 582. Serial Wire Debug pin description
Pin Name
Type
Description
SWDCLK
Input
Serial Wire Clock.
This pin is the clock for debug logic when in the
Serial Wire Debug mode.
SWDIO
Input /
Output
Serial wire debug data input/output.
The SWDIO pin is used by an
external debug tool to communicate with and control the Cortex-M3
CPU.
SWO
Output
Serial Wire Output.
The SWO pin optionally provides data from the
ITM and/or the ETM for an external debug tool to evaluate.
Table 583. Parallel Trace pin description
Pin Name
Type
Description
TRACECLK
Input
Trace Clock.
This pin provides the sample clock for trace data on
the TRACEDATA pins when tracing is enabled by an external debug
tool.
TRACEDATA[3:0]
Output
Trace Data bits 3 to 0.
These pins provide ETM trace data when
tracing is enabled by an external debug tool. The debug tool can
then interpret the compressed information and make it available to
the user.