15.3.2.5 Compact Vector Table

The Compact Vector Table (CVT) is a feature to allow the writing of compact code by having all level 0 interrupts share the same interrupt vector number. Thus, the interrupts share the same Interrupt Service Routine (ISR). This reduces the number of interrupt handlers and thereby frees up memory that can be used for the application code.

When CVT is enabled by writing a ‘1’ to the CVT bit in the Control A (CPUINT.CTRLA) register, the vector table contains these three interrupt vectors:
  1. The non-maskable interrupts (NMI) at vector address 1.
  2. The Priority Level 1 (LVL1) interrupt at vector address 2.
  3. All priority level 0 (LVL0) interrupts at vector address 3.

This feature is most suitable for devices with limited memory and applications using a few of interrupt generators.