Embeddedice Logic; Features; Applications; Description - Philips LPC2194 User Manual

Philips Semiconductors
ARM-based Microcontroller
21. E
MBEDDED

FEATURES

• No target resources are required by the software debugger in order to start the debugging session
• Allows the software debugger to talk via a JTAG (Joint Test Action Group) port directly to the core
• Inserts instructions directly in to the ARM7TDMI-S core
• The ARM7TDMI-S core or the System state can be examined, saved or changed depending on the type of instruction inserted
• Allows instructions to execute at a slow debug speed or at a fast system speed

APPLICATIONS

The EmbeddedICE logic provides on-chip debug support. The debugging of the target system requires a host computer running
the debugger software and an EmbeddedICE protocol convertor. EmbeddedICE protocol convertor converts the Remote Debug
Protocol commands to the JTAG data needed to access the ARM7TDMI-S core present on the target system.

DESCRIPTION

The ARM7TDMI-S Debug Architecture uses the existing JTAG
are around the core for production test are reused in the debug state to capture information from the databus and to insert new
information into the core or the memory. There are two JTAG-style scan chains within the ARM7TDMI-S. A JTAG-style Test
Access Port Controller controls the scan chains. In addition to the scan chains, the debug architecture uses EmbeddedICE logic
which resides on chip with the ARM7TDMI-S core. The EmbeddedICE has its own scan chain that is used to insert watchpoints
and breakpoints for the ARM7TDMI-S core. The EmbeddedICE logic consists of two real time watchpoint registers, together with
a control and status register. One or both of the watchpoint registers can be programmed to halt the ARM7TDMI-S core.
Execution is halted when a match occurs between the values programmed into the EmbeddedICE logic and the values currently
appearing on the address bus, databus and some control signals. Any bit can be masked so that its value does not affect the
comparison. Either watchpoint register can be configured as a watchpoint (i.e. on a data access) or a break point (i.e. on an
instruction fetch). The watchpoints and breakpoints can be combined such that:
• The conditions on both watchpoints must be satisfied before the ARM7TDMI core is stopped. The CHAIN functionality requires
two consecutive conditions to be satisfied before the core is halted. An example of this would be to set the first breakpoint to
trigger on an access to a peripheral and the second to trigger on the code segment that performs the task switching. Therefore
when the breakpoints trigger the information regarding which task has switched out will be ready for examination.
• The watchpoints can be configured such that a range of addresses are enabled for the watchpoints to be active. The RANGE
function allows the breakpoints to be combined such that a breakpoint is to occur if an access occurs in the bottom 256 bytes
of memory but not in the bottom 32 bytes.
The ARM7TDMI-S core has a Debug Communication Channel function in-built. 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.
* For more details refer to IEEE Standard 1149.1 - 1990 Standard Test Access Port and Boundary Scan Architecture.

EmbeddedICE Logic

ICE LOGIC
LPC2119/2129/2194/2292/2294
*
port as a method of accessing the core. The scan chains that
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Preliminary User Manual
May 03, 2004