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Power Domain and Module Topology
8.2.2.2
Local Reset
In addition to module reset, the following module can be reset using a special local reset that is also a part
of the PSC module control for resets.
•
ARM: When the ARM local reset is asserted the entire ARM processor is reset , including cache etc.
This does not include the ARM RAM/ROM or ARM interrupt controller module as these exist outside
the ARM core. The local reset for ARM additionally ensures that any outstanding requests are
completed before ARM is reset, therefore for scenarios where it is needed to just reset the ARM locally
but not change the state of clocks, user can use ARM local reset feature.
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.
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
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
for additional considerations, constraints, limitations around
this mode.
109
SPRUGX5A
–
May 2011
Power and Sleep Controller (PSC)
Copyright
©
2011, Texas Instruments Incorporated
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