PM0215 datasheet(67/91 Pages) STMICROELECTRONICS

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PM0215

The STM32 Cortex-M0 instruction set

Doc ID 022979 Rev 1

67/91

3.7.10

SVC

Supervisor call.

Syntax

SVC #imm

where: ‘imm’ is an integer in the range 0-255.

Operation

The SVC instruction causes the SVC exception. imm is ignored by the processor. It can be

retrieved by the exception handler to determine what service is being requested.

Restrictions: None

Condition flags

This instruction does not change the flags.

Examples

SVC

0x32

; Supervisor Call (SVC handler can extract the immediate value

; by locating it via the stacked PC)

3.7.11

WFE

Wait for event. WFE is a hint instruction.

Syntax

WFE

Operation

If the event register is 0, WFE suspends execution until one of the following events occurs:

●

An exception, unless masked by exception mask registers or the current priority level

●

An exception enters Pending state, if SEVONPEND in system control register is set

●

A Debug Entry request, if Debug is enabled

●

An event signaled by a peripheral or another processor in a multiprocessor system

using the SEV instruction.

If the event register is 1, WFE clears it to 0 and returns immediately. For more information

see Power management on page 28.

WFE is intended for power saving only. When writing software assume that WFE might

behave as NOP.

Restrictions: None

Condition flags

This instruction does not change the flags.

Examples

WFE

; Wait for event

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