Power Management
e200z3 Power Architecture Core Reference Manual, Rev. 2
8-2
Freescale Semiconductor
is a power management state diagram.
Figure 8-1. Power Management State Diagram
8.1.1
Power Management Signals
summarizes power management signals. More detailed information is provided in
Table 8-2. Descriptions of Timer Facility and Power Management Signals
Signal
I/O
Signal Description
p_halt
I
Processor halt request. The active-high
p_halt input requests that the core enter the halted state.
p_halted
O
Processor halted. The active-high
p_halted
output indicates that the core entered the halted state.
p_stop
I
Processor stop request. The active-high
p_stop input requests that the core enter the stopped state.
p_stopped
O
Processor stopped. The active-high
p_stopped output indicates that the core entered stopped state.
p_doze
p_nap
p_sleep
O
Low-power mode. These signals are asserted by the core to reflect the settings of the HID0[DOZE],
HID0[NAP], and HID0[SLEEP] control bits when MSR[WE] is set. The core can be placed in a low-power
state by forcing
m_clk to a quiescent state, and brought out of low-power state by re-enabling m_clk. The
time base facilities may be separately enabled or disabled using combinations of the timer facility control
signals.
p_wakeup
O
Wakeup. Used by external logic to remove the core and system logic from a low-power state. It can also
indicate to the system clock controller that
m_clk should be re-enabled for debug purposes.
p_wakeup (or other system state) should be monitored to determine when to release the core (and system
if applicable) from a low-power state.
p_tbdisable
I
Timer disable. Used to disable the internal time base and decrementer counters. This signal can be used
to freeze the state of the time base and decrementer during low power or debug operation.
p_tbclk
I
Timer external clock. Used as an alternate clock source for the time base and decrementer counters.
Selection of this clock is made using HID0[SEL_TBCLK] (see
Implementation-Dependent Register 0 (HID0)”
).
p_tbint
O
Timer interrupt status. Indicates whether an internal timer facility unit is requesting an interrupt
(TSR[WIS] = 1 and TCR[WIE] = 1, or TSR[DIS] = 1 and TCR[DIE] = 1, or
TSR[FIS] = 1 and TCR[FIE] = 1). May be used to exit low-power operation or for other system purposes.
Halted
Power-Down
~
p_stop & p_halt
p_stop
~
p_halt & ~p_stop
p_halt | p_stop
~
p_stop
p_stop
Active
~
p_halt & ~p_stop
(
p_stopped asserted)
(
p_halted asserted)