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Introduction
10.1 Introduction
The system configuration (SYSCFG) module is a system-level module containing status and top level
control logic required by the device. The system configuration module consists of a set of
memory-mapped status and control registers, accessible by the CPU, supporting all of the following
system features, and miscellaneous functions and operations.
•
Device Identification
•
Device Configuration
–
Pin multiplexing control
–
Device Boot Configuration Status
•
Master Priority Control
–
Controls the system priority for all master peripherals (including EDMA3TC)
•
Emulation Control
–
Emulation suspend control for peripherals that support the feature
•
Special Peripheral Status and Control
–
Locking of PLL control settings
–
Default burst size configuration for EDMA3 transfer controllers
–
McASP0 AMUTEIN selection and clearing of AMUTE
–
USB PHY Control
–
Clock source selection for EMIFA and DDR2/mDDR
The system configuration module controls several global operations of the device; therefore, the module
supports protection against erroneous and illegal accesses to the registers in its memory-map. The
protection mechanisms that are present in the module are:
•
A special key sequence that needs to be written into a set of registers in the system configuration
module, to allow write ability to the rest of registers in the system configuration module.
•
Several registers in the module are only accessible when the CPU requesting read/write access is in
privileged mode.
10.2 Protection
The SYSCFG module controls several global operations of the device; therefore, it has a protection
mechanism that prevents spurious and illegal accesses to the registers in its memory map. The protection
mechanism enables accesses to these registers only if certain conditions are met.
10.2.1 Privilege Mode Protection
The CPU supports two privilege levels: Supervisor and User. Several registers in the SYSCFG
memory-map can only be accessed when the accessing host (CPU or master peripheral) is operating in
privileged mode, that is, in Supervisor mode. The registers that can only be accessed in privileged mode
are listed in
. See the ARM926EJ-S Technical Reference Manual (TRM), downloadable from
http://infocenter.arm.com/help/index.jsp
for details on privilege levels.
146
System Configuration (SYSCFG) Module
SPRUGX5A
–
May 2011
Copyright
©
2011, Texas Instruments Incorporated
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