Register Model
e200z3 Power Architecture Core Reference Manual, Rev. 2
2-36
Freescale Semiconductor
2.12.2
Debug Counter Register (DBCNT)
The debug counter register (DBCNT) contains two 16-bit counters (CNT1 and CNT2) that can be
configured to operate independently or concatenated into a single 32-bit counter. Each counter can be
configured to count down (decrement) when one or more count-enabled events occur. The counters
operate regardless of whether counters are enabled to generate debug exceptions. When a count value
reaches zero, a debug count event is signaled and a debug event can be generated (if enabled). Upon
reaching zero, the counter is frozen. A debug counter signals an event on the transition from a value of one
to a final value of zero. Loading a value of zero into the counter prevents the counter from counting. The
debug counter is configured by the contents of DBCR3. DBCNT is shown in
.
Refer to
Section 2.12.3.4, “Debug Control Register 3 (DBCR3),”
for details on updates to the DBCNT
register. There are restrictions on how the DBCNT and DBCR3 register are modified when one or more
counters are enabled.
2.12.3
Debug Control and Status Registers (DBCR0–DBCR3)
DBCR0–DBCR3 enable debug events, reset the processor, control timer operation during debug events
and set the debug mode of the processor. The debug status register (DBSR) records debug exceptions while
internal or external debug mode is enabled.
To ensure that any alterations enabling/disabling debug events are effective, the e200z3 requires that a
context synchronizing instruction follow an mtspr that updates a DBCR or DBSR. The context
synchronizing instruction may or may not be affected by the alteration. Typically, an isync is used to create
a synchronization boundary beyond which it can be guaranteed that the newly written control values are
in effect. For watchpoint generation and counter operation, configuration settings in DBCR1–DBCR3 are
used, even though the corresponding events can be disabled (via DBCR0) from setting DBSR flags.
2.12.3.1
Debug Control Register 0 (DBCR0)
DBCR0 is used to enable debug modes and controls which debug events are allowed to set DBSR flags.
The e200z3 adds bits to this register, as shown in
.
32
47 48
63
Field
CNT1
CNT2
Reset
Undefined on
m_por assertion, unchanged on p_reset_b
assertion
R/W
R/W
SPR
SPR 562
Figure 2-32. DBCNT Register
Содержание e200z3
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