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PC.19:16
PC.15:0
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Interrupts
4.2
Interrupts
The MSP430X has the following interrupt structure:
•
Vectored interrupts with no polling necessary
•
Interrupt vectors are located downward from address 0FFFEh.
The interrupt vectors contain 16-bit addresses that point into the lower 64-KB memory. This means all
interrupt handlers must start in the lower 64-KB memory.
During an interrupt, the program counter (PC) and the status register (SR) are pushed onto the stack as
shown in
. The MSP430X architecture stores the complete 20-bit PC value efficiently by
appending the PC bits 19:16 to the stored SR value automatically on the stack. When the RETI instruction
is executed, the full 20-bit PC is restored making return from interrupt to any address in the memory range
possible.
Figure 4-2. PC Storage on the Stack for Interrupts
90
CPUX
SLAU272C – May 2011 – Revised November 2013
Copyright © 2011–2013, Texas Instruments Incorporated