Subject : Embedded Systems Design

Topic : Embedded Hardware and Design

Difficulty level : Medium

• Cortex CPU has sleep mode i.e it places core into its power mode where it halts execution of instruction with cortex CPU.
• A small part of CPU is kept awake so that peripheral interrupts can wake up cortex Core.
• The instruction WFI (wait for interrupt) or WFE (wait for event) is executed to place cortex core into sleep mode.
• WFI instruction: Core will resume execution and serve pending instruction. It allows low power application to be completely interrupt driven so that core wake up run the code and re-enter into sleep mode.
• WFE instruction: It allows the cortex Core to resume execution from the point where it was placed into sleep mode.
• WFI & WFE are called using macros.