UM11029
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© NXP Semiconductors N.V. 2017. All rights reserved.
User manual
Rev. 1.0 — 16 June 2017
489 of 515
31.1 How to read this chapter
The debug functionality is identical for all LPC84x parts.
31.2 Features
•
Supports ARM Serial Wire Debug mode.
•
Direct debug access to all memories, registers, and peripherals.
•
No target resources are required for the debugging session.
•
Four breakpoints.
•
Two data watchpoints that can also be used as triggers.
•
Supports JTAG boundary scan.
•
Micro Trace Buffer (MTB) supported.
31.3 General description
Debug functions are integrated into the ARM Cortex-M0+. Serial wire debug functions are
supported. The ARM Cortex-M0+ is configured to support up to four breakpoints and two
watchpoints.
Support for boundary scan and Micro Trace Buffer is available. In order to use the
micro-trace buffer for debugging, enable the MTB clock in the SYSAHBCLKCTRL register
(
Only RAM0 can be used as trace buffer by MTB, that means the maximum trace buffer
size is 4 KB.
31.4 Pin description
The SWD functions are assigned to pins through the switch matrix. The SWD functions
are fixed-pin functions that are enabled through the switch matrix and can only be
assigned to special pins on the package. The SWD functions are enabled by default.
See
to enable the analog comparator inputs and the reference voltage
input.
UM11029
Chapter 31: LPC84x Serial Wire Debug (SWD)
Rev. 1.0 — 16 June 2017
User manual
Table 476. SWD pin description
Function
Type Pin
Description
SWM register
Reference
SWCLK
I/O
SWCLK/PIO0_3/
TCK
Serial Wire
Clock.
This pin is the clock for SWD
debug logic when in the Serial Wire Debug mode
(SWD). This pin is pulled up internally.
PINENABLE0
SWDIO
I/O
SWDIO/PIO0_2/
TMS
Serial wire debug data input/output.
The SWDIO
pin is used by an external debug tool to
communicate with and control the LPC84x. This pin
is pulled up internally.
PINENABLE0