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They take up space in the target system memory
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They have to change (save and restore) the context of the userÕs application to run
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They are ineffective at debugging boot code that initializes the hardware or ROM resident debugger
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They often cannot set breakpoints in ROM
PowerPC microprocessors provide on-chip debugging logic to overcome some of these deÞciencies and
provide other capability without storing code in memory or having to save and restore the state of the UserÕs
program. SpeciÞcally, the PowerPC on-chip debugging support includes:
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Run control - the ability to halt, single step, resume execution , or go to a speciÞc address and begin
execution.
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Display and modiÞcation of registers and processor resources
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Display, modify and download to memory (possibly including on chip memory like cache and/or
TLBs)
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Display, setting, removal of instruction breakpoints in hardware
This capability is accessed by sending commands to the common on-chip processor (COP) through the
JTAG (Joint Test Advision Group or IEEE1149.1 standard) interface. A connector is provided to access this
on Excimer and numerous third parties provide software and hardware to take advantage of it while
debugging code. The Excimer kit includes an inexpensive Wiggler JTAG/COP interface from Macraigor
Systems, Inc.
1.1 The Wiggler
The Wiggler from Macraigor Systems is an inexpensive JTAG/COP interface for run control and debug of
the PowerPC Microprocessor though the parallel port of the PC. It translates software commands from
various debugger vendors such as Cygnus, Green Hills, Metaware, Metrowerks, Microtec, Motorola, SDS,
Tasking, and Wind River that utilize MacraigorÕs On-Chip Debug (OCD) Application Programming
Interface (API). The Wiggler supports various Motorola microprocessors including CPU32, MPC5xx,
MPC6xx, MPC7xx, MPC8xx, etc.
Macraigor provides several different but compatible products that perform this function at increasing levels
of performance, functionality, and cost. The Wiggler is the least expensive, simplest device and provides an
appropriate level of performance and capability for an inexpensive evaluation kit like Excimer, but for more
serious software and hardware development the user may be interested in higher capability JTAG/COP
interface tools from Macraigor or other vendors.
The third party debugger solutions provided by developers in the Excimer kit may utilize the Wiggler
interface. Check their documentation.
Macraigor Systems provides a software application that tests and exercises the Wiggler and that can be used
to control the processor, examine registers or memory, download code, etc. The Macraigor application is
included in the Excimer kit and instructions for loading it onto WindowsNT or Windows95 are described in
Section 1.2, ÒInstalling the Wiggler Software.Ó
1.2 Installing the Wiggler Software
To install Wiggler on Windows NT:
1. Log on as administrator.
2. Copy the file setupex.exe to a temporary directory.
MOTOROLA
Minimal PowerPC 603e Evaluation Board
7
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