world leader in high performance signal processing
Trace: » sti

Enable Interrupts

General Form



STI Dreg ; /* previous state of IMASK restored from Dreg (a) */

Syntax Terminology

Dreg: R7–0

Instruction Length

In the syntax, comment (a) identifies 16-bit instruction length.

Functional Description

The Enable Interrupts instruction globally enables interrupts by restoring the previous state of the interrupt system back into IMASK.

Flags Affected


Required Mode

The Enable Interrupts instruction executes only in Supervisor mode. If execution is attempted in User mode, the instruction produces an Illegal Use of Protected Resource exception.

Parallel Issue

The Enable Interrupts instruction cannot be issued in parallel with other instructions.


sti r3 ;

Also See

Special Applications

This instruction is often located after an IDLE instruction so that it will execute after a wake-up event from the idle state.