LPC2420_60 NXP Semiconductors, LPC2420_60 Datasheet - Page 47
Manufacturer Part Number
NXP Semiconductors designed the LPC2420/2460 microcontroller around a 16-bit/32-bitARM7TDMI-S CPU core with real-time debug interfaces that include both JTAG andembedded trace
The JTAG clock (TCK) must be slower than
interface to operate.
7.26.2 Embedded trace
Since the LPC2420/2460 have significant amounts of on-chip memories, it is not possible
to determine how the processor core is operating simply by observing the external pins.
The ETM provides real-time trace capability for deeply embedded processor cores. It
outputs information about processor execution to a trace port. A software debugger allows
configuration of the ETM using a JTAG interface and displays the trace information that
has been captured.
The ETM is connected directly to the ARM core and not to the main AMBA system bus. It
compresses the trace information and exports it through a narrow trace port. An external
Trace Port Analyzer captures the trace information under software debugger control. The
trace port can broadcast the Instruction trace information. Instruction trace (or PC trace)
shows the flow of execution of the processor and provides a list of all the instructions that
were executed. Instruction trace is significantly compressed by only broadcasting branch
addresses as well as a set of status signals that indicate the pipeline status on a cycle by
cycle basis. Trace information generation can be controlled by selecting the trigger
resource. Trigger resources include address comparators, counters and sequencers.
Since trace information is compressed the software debugger requires a static image of
the code being executed. Self-modifying code can not be traced because of this
RealMonitor is a configurable software module, developed by ARM Inc., which enables
real-time debug. It is a lightweight debug monitor that runs in the background while users
debug their foreground application. It communicates with the host using the DCC, which is
present in the EmbeddedICE logic. The LPC2420/2460 contain a specific configuration of
RealMonitor software programmed into the on-chip ROM memory.
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 6.1 — 22 September 2011
Flashless 16-bit/32-bit microcontroller
of the CPU clock (CCLK) for the JTAG
© NXP B.V. 2011. All rights reserved.
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