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Power Domain and Module Topology
143
SPRUH91D–March 2013–Revised September 2016
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Power and Sleep Controller (PSC)
Table 8-3. Module States
Module State Module Reset Module Clock Module State Definition
Enable De-asserted On A module in the enable state has its module reset de-asserted and it has its
clock on. This is the normal operational state for a given module
Disable De-asserted Off A module in the disabled state has its module reset de-asserted and it has its
module clock off. This state is typically used for disabling a module clock to
save power. This 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.
SyncReset Asserted On A module state in the SyncReset state has its module reset asserted and it has
its clock on. Generally, software is not expected to initiate this state
SwRstDisable Asserted Off A module in the SwResetDisable state has its module reset asserted and it has
its clock disabled. After initial power-on, several modules come up in the
SwRstDisable state. Generally, software is not expected to initiate this state
Auto Sleep De-asserted Off A module in the Auto Sleep state also has its module reset de-asserted and its
module clock disabled, similar to the Disable state. However this is a special
state, once a module is configured in this state by software, it can
“automatically” transition to “Enable” state whenever there is an internal
read/write request made to it, and after servicing the request it will
“automatically” transition into the sleep state (with module reset re de-asserted
and module clock disabled), without any software intervention. The transition
from sleep to enabled and back to sleep state has some cycle latency
associated with it. It is not envisioned to use this mode when peripherals are
fully operational and moving data. See Section 8.2.2.1 for additional
considerations, constraints, limitations around this mode.
Auto Wake De-asserted Off A module in the Auto Wake state also has its module reset de-asserted and its
module clock disabled, similar to the Disable state. However this is a special
state, once a module is configured in this state by software, it will
“automatically” transition to “Enable” state whenever there is an internal
read/write request made to it, and will remain in the “Enabled” state from then
on (with module reset re de-asserted and module clock on), without any
software intervention. The transition from sleep to enabled state has some
cycle latency associated with it. It is not envisioned to use this mode when
peripherals are fully operational and moving data. See Section 8.2.2.1 for
additional considerations, constraints, limitations around this mode.
8.2.2.2 Local Reset
In addition to module reset, some modules can be reset using a special local reset that is also a part of
the PSC module control for resets. The modules that support the local reset are:
• DSP: When the DSP local reset is asserted the DSP internal memories (L1P, L1D and L2) are still
accessible. The local reset only resets the DSP CPU core, not the rest of DSP subsystem, as the DSP
module reset would. Local Reset is useful in cases where the DSP is in enable or disable state; since
when module is in SyncReset or SwRstDisable state the module reset is asserted, and the module
reset takes precedence over the local reset.
The procedures for asserting and de-asserting the local reset are as follows (where n corresponds to the
module that supports local reset):
1. Clear the LRST bit in the module control register (MDCTLn) to 0 to assert the module’s local reset.
2. Set the LRST bit in the module control register (MDCTLn) to 1 to de-assert module’s local reset.
If the CPU is in the enable state, it immediately executes program instructions after reset is de-asserted.
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