NMI Configuration
315
SLAU356I – March 2015 – Revised June 2019
Copyright © 2015–2019, Texas Instruments Incorporated
System Controller A (SYSCTL_A)
5.2.2.1
SRAM Bank Enable Configuration
The application can optimize the power consumption of the SRAM. The SRAM is divided into banks that
can individually be powered down. Banks that are powered down remain powered down in both active and
low-power modes of operation, thereby limiting any unnecessary inrush current when the device
transitions between active and retention based low-power modes. The application can choose to disable
one (or more) banks for a certain stage in the processing and re-enable it for another stage.
When a particular bank is disabled, reads to its address space return 0h, and writes are discarded. To
prevent holes in the memory map, if a particular bank is enabled, all the lower banks are also forced to
enabled state. This ensures a contiguous memory map through the set of enabled banks instead of a
allowing a disabled bank to appear between enabled banks. For example:
•
If there are eight banks in the device, values of 00111111 and 00000111 are acceptable.
•
Values like 00010111 are not valid, and the resultant bank configuration is automatically set to
00011111.
•
For example, for a 8-bank SRAM, the allowed values are 00000001, 00000011, 00000111, 00001111,
00011111, 00111111, 01111111, and 11111111.
Bank0 of SRAM is always enabled and cannot be disabled. For all other banks, any enable or disable
change results in the BNKEN_RDY bit of the SYS_SRAM_STAT register being set to 0 until the
configuration change is effective. Access to the SRAM is stalled during this time, and access resumes
only after the SRAM banks are ready for read or write operations. This is handled transparently and does
not require any code intervention.
5.2.2.2
SRAM Block Retention Configuration
The application can optimize the leakage power consumption of the SRAM in LPM3 and LPM4 modes of
operation by individually configuring each SRAM block within a bank for retention. Blocks that are enabled
for retention retain data through the LPM3 and LPM4 modes. The SRAM bank in which the block resides
must be enabled for the block to be retained during LPM3 and LPM4.
For example (see
), the application may need 128KB of SRAM for its processing needs
(assume two banks are kept enabled), but of these, only two blocks (2 × 8KB) contain critical data that
needs to be retained in LPM3 or LPM4, while the rest of the blocks are powered off to minimize power
consumption. See the SYS_SRAM_BLKRET_CTLx register description for details on SRAM block
retention configuration.
Block 0 of SRAM is always retained and cannot be disabled for retention. Therefore, it can operate as
backup memory in the LPM3, LPM4, and LPM3.5 modes of operation.
5.3
NMI Configuration
The following NMI sources are available on MSP432P4xx devices.
•
RSTn/NMI device pin in NMI configuration
•
Clock System (CS) sources
•
Power Supply System (PSS) sources
•
Power Control Manager (PCM) sources
See the SYS_NMI_CTLSTAT register for configuration and status of different NMI sources available on
the device. These NMI sources can also be configured as maskable interrupts through appropriate
programming of the NVIC registers.
5.4
Watchdog Timer Reset Configuration
The Watchdog Timer module generates a reset on a password violation or time-out while in watchdog
timer mode of operation. The watchdog timer module can be configured to source a hard reset or soft
reset in the SYS_WDTRESET_CTL register.