e200z3 Power Architecture Core Reference Manual, Rev. 2
Freescale Semiconductor
9-1
Chapter 9
Debug Support
9.1
Introduction
This chapter describes the debug features of the e200z3 core, including the software and hardware debug
facilities, events, and registers. It also details the external debug support features available and introduces
the reader to the on-chip emulation circuitry (OnCE) and its key attributes, that is, the interface signals,
debug inputs, and outputs. This chapter also covers watchpoint support, MMU and cache operations
during debug, cache array access, and the basic steps for enabling, using, and exiting external debug mode.
9.2
Overview
Internal debug support in the core allows for software and hardware debugging by providing debug
functions such as instruction and data breakpoints and program trace modes. For software-based
debugging, debug facilities consisting of a set of software-accessible debug registers and interrupt
mechanisms are provided. These facilities are also available to a hardware-based debugger that
communicates using a modified IEEE 1149.1 test access port (TAP) controller and pin interface. When
hardware debugging is enabled, the debug facilities are protected from software modification.
Software debug facilities are defined as part of Book E. The core supports a subset of these defined
facilities. In addition to the Book E–defined facilities, the core provides additional flexibility and
functionality in the form of debug event counters, linked instruction and data breakpoints, and sequential
debug event detection. These features are also available to a hardware-based debugger.
The core also supports an external Nexus real-time debug module. Real-time system-level debugging is
supported by an external Nexus class 2, 3, or 4 module. Definitions and features of this module are part of
the system/platform specification and are not further defined in this chapter. Additional information can
be found in
9.2.1
Software Debug Facilities
The debug facilities enable hardware and software debug functions, such as instruction and data
breakpoints and program single-stepping. The debug facilities consist of a set of debug control registers
(DBCR0–DBCR3) (e200z335 also includes DBCR4 and DBERC0), a set of address compare registers
(IAC1–IAC4, DAC1, and DAC2), a set of data value compare registers (DVC1, DVC2) in e200z335, a
configurable debug counter register (DBCNT), a debug status register (DBSR) for enabling and recording
various kinds of debug events, and a special debug interrupt type built into the interrupt mechanism (see
Section 4.6.16, “Debug Interrupt (IVOR15),”
for more information). The debug facilities also provide
mechanisms for software-controlled processor reset and for controlling the operation of the timers in a
debug environment.
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