UM10503
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© NXP B.V. 2012. All rights reserved.
User manual
Rev. 1.3 — 6 July 2012
1209 of 1269
NXP Semiconductors
UM10503
Chapter 48: LPC43xx JTAG, Serial Wire Debug (SWD), and trace
48.5 Pin Description
to
indicate the various pin functions related to debug and trace.
Some of these functions share pins with other functions which therefore may not be used
at the same time. Use of the JTAG port excludes use of Serial Wire Debug and Serial
Wire Output. Use of the parallel trace requires five pins that may be part of the user
application, limiting debug possibilities for those features. Trace using the Serial Wire
Output does not have this limitation but the bandwidth is limited.
48.6 Debug connections
The LPC43xx supplies dedicated pins for JTAG and Serial Wire Debug (SWD). When a
debug session is started, the part will be in JTAG debug mode. Once in debug mode, the
debugger can switch the device to SWD mode.
Table 1079.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.
Table 1080.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-M4
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.
Remark:
The core frequency must be 120 MHz or lower to use the
SWO.
Table 1081.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.