Item n−1
PC.19:16
PC.15:0
SP
old
SP
SR.11:0
Interrupts
115
SLAU367P – October 2012 – Revised April 2020
Copyright © 2012–2020, Texas Instruments Incorporated
CPUX
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 64KB memory. This means all
interrupt handlers must start in the lower 64KB 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