Sys Interrupt Vector Generators - Texas Instruments MSP430FR57 Series User Manual

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Some interrupt enable bits and interrupt flags, as well as control bits for the RST/NMI pin, are located in
the special function registers (SFR). The SFR are located in the peripheral address range and are byte
and word accessible. See the device-specific data sheet for the SFR configuration.
1.3.6.1 Alternate Interrupt Vectors
On devices that contain RAM, it is possible to use the RAM as an alternate location for the interrupt vector
locations. Setting the SYSRIVECT bit in SYSCTL causes the interrupt vectors to be remapped to the top
of RAM. Once set, any interrupt vectors to the alternate locations now residing in RAM. Because
SYSRIVECT is automatically cleared on a BOR, it is critical that the reset vector at location 0FFFEh still
be available and handled properly in firmware.

1.3.7 SYS Interrupt Vector Generators

SYS collects all system NMI (SNMI) sources, user NMI (UNMI) sources, and BOR, POR, or PUC (reset)
sources of all the other modules. They are combined into three interrupt vectors. The interrupt vector
registers SYSRSTIV, SYSSNIV, SYSUNIV are used to determine which flags requested an interrupt or a
reset. The interrupt with the highest priority of a group, when enabled, generates a number in the
corresponding SYSRSTIV, SYSSNIV, SYSUNIV register. This number can be directly added to the
program counter, causing a branch to the appropriate portion of the interrupt service routine. Disabled
interrupts do not affect the SYSRSTIV, SYSSNIV, SYSUNIV values. Reading SYSRSTIV, SYSSNIV,
SYSUNIV register automatically resets the highest pending interrupt flag of that register. If another
interrupt flag is set, another interrupt is immediately generated after servicing the initial interrupt. Writing to
the SYSRSTIV, SYSSNIV, SYSUNIV register automatically resets all pending interrupt flags of the group.
SLAU272C – May 2011 – Revised November 2013
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System Resets, Interrupts, and Operating Modes, System Control Module
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Interrupts
33
(SYS)