7.4
Executing State Transitions
7.4.1 Power Domain State Transitions
7.4.2 Module State Transitions
7.5
IcePick Emulation Support in the PSC
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Executing State Transitions
The module states are defined as follows:
Module State
Module State Definition
Enable
A module in the enable state has its module reset de-asserted and it has its clock on. This is
the normal run-time state for a given module.
Disable
A module in the disable state has its module reset de-asserted and it has its clock off. This
state is typically used for disabling a module clock to save static power. The device is
designed in full static CMOS, so when you stop a module clock, it retains the module's state.
When the clock is restarted, the module resumes operating from the stopping point.
SyncRst
A module in the SyncReset state has its module reset asserted and it has its clock on. After
initial power-on, most modules are in the SyncRst state by default (see
).
Generally, software is not expected to initiate this state.
SwRstDisable
A module in the SwResetDisable state has its module reset asserted and it has its clock set
to off. Generally, software is not expected to initiate this state.
This section describes how to execute state transitions for power domains and modules.
The AlwaysOn Power Domain is automatically transitioned to the ON state upon power-on-reset. No
software intervention is required; the transition is automatically handled by the hardware.
This section describes the procedure for transitioning the module state. The procedure for module state
transitions is as follows (‘x’ corresponds to the module):
•
Wait for the GOSTATx bit in PTSTAT to clear to 0x0. You must wait for any previously initiated
transitions to finish before initiating a new transition.
•
Set the NEXT bit in MDCTL[x] to SwRstDisable (0x0), SyncReset (0x1), Disable (0x2), or Enable (0x3).
Note:
You may set transitions in multiple NEXT bits in MDCTL[x] in this step.
•
Set the GOx bit in PTCMD to 0x1 to initiate the transition(s).
•
Wait for the GOSTATx bit in PTSTAT to clear to 0x0. The module is only safely in the new state after
the GOSTATx bit in PTSTAT clears to 0x0.
The PSC supports IcePick commands that allow IcePick aware emulation tools to have some control over
the state of power domains and modules.
In particular, the PSC supports the following IcePick emulation commands:
Table 7-3. IcePick Emulation Commands
Power On and Enable Features
Power On and Enable Descriptions
Reset Features
Reset Descriptions
Inhibit Sleep
Allows emulation to prevent software from Assert Reset
Allows emulation to assert
transitioning the power domain out of the
the module’s local reset.
on state and to prevent software from
transitioning the module out of the enable
state
Force Power
Allows emulation to force the power
Wait Reset
Allows emulation to keep
domain into an on state
local reset asserted for an
extended period of time
after software initiates local
reset de-assert.
SPRUFX7 – July 2008
Power and Sleep Controller
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