Lp

This section introduces the Low Power (LP) APIs including terms and acronyms, supported features, software architecture, details on how to use this driver, enums, structures and functions. More...

Overview

This section introduces the Low Power (LP) APIs including terms and acronyms, supported features, software architecture, details on how to use this driver, enums, structures and functions.

Terms and Acronyms

Terms	Details
LP	Low Power.
LSLP	Legacy Sleep Low Power.
DSLP	Deep Sleep Low Power.

Supported Features

The ARM Cortex-M4F I/O subsystems support three kinds of low power scenarios, including CPU Clock Gating Low Power Scenario, Legacy Sleep Low Power Scenario, and Deep Sleep Low Power Scenario.
For more details, please refer to LP datasheet.

How to use this driver

• SW Architecture:
  
  • LP driver only has OS HAL and the driver flow for entering low power scenario is as follows:
    • Check whether WIC has a pending wake-up event.
    • Disable ARM Cortex-M4F I/O subsystems systick.
    • Prevent exception service.
    • Configure wake-up source so that system can resume.
    • Configure memory power and set low power control bit.
    • Trigger WFI to enter low power scenario.
      
  • The driver flow for resuming is as follows. (Note that this flow doesn't apply for deep sleep low power scenario, which uses reboot flow.)
    • Restore exception service.
    • Enable ARM Cortex-M4F I/O subsystems systick.
• Device driver sample code is as follows:
  This section describes the definition of APIs and provides an example of how to use these APIs to enter different low power scenarios.
  
  • sample code (this is the user application sample code):

    // first call this function to clear deep sleep low power scenario bit
    mtk_os_hal_lp_dslp_check(PRE_DEEP_SLEEP);
    
    // call this function to enter selected low power scenario
    // in the example below, select GPT3 as wake-up source and enter DSLP
    mtk_os_hal_lp_enter(GPT3_WAKEUP_SRC_24, DEEP_SLEEP);

Modules
	Enum
	This section introduces the enumerations that LP should configure before entering LP.
	Function
	This section provides Fixed APIs (defined as Common Interface) to fully support three low power scenarios of ARM Cortex-M4F I/O subsystems.