LPC2212/2214
NXP Semiconductors
16/32-bit ARM microcontrollers
The ARM core has a Debug Communication Channel function built-in. The debug
communication channel allows a program running on the target to communicate with the
host debugger or another separate host without stopping the program flow or even
entering the debug state. The debug communication channel is accessed as a
co-processor 14 by the program running on the ARM7TDMI-S core. The debug
communication channel allows the JTAG port to be used for sending and receiving data
without affecting the normal program flow. The debug communication channel data and
control registers are mapped in to addresses in the EmbeddedICE logic.
The JTAG clock (TCK) must be slower than 1⁄6 of the CPU clock (CCLK) for the JTAG
interface to operate.
6.19.2 Embedded trace macrocell
Since the LPC2212/2214 have significant amounts of on-chip memory, it is not possible to
determine how the processor core is operating simply by observing the external pins. The
Embedded Trace Macrocell (ETM) provides real-time trace capability for deeply
embedded processor cores. It outputs information about processor execution to the trace
port.
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 must capture the trace information under software debugger control.
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 restriction.
6.19.3 RealMonitor
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 (Debug
Communications Channel), which is present in the EmbeddedICE logic. The
LPC2212/2214 contain a specific configuration of RealMonitor software programmed into
the on-chip flash memory.
LPC2212_2214_4
© NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 04 — 3 January 2008
25 of 45
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