Considerations#

This section focuses on considerations when working with Power Manager.

Add/Remove PS requirement#

The current state of the M4 is the most recent active state it transitioned to. For instance, if the PS4 state requirement is added and then removed, followed by the addition and removal of the PS3 state, the current state of the M4 would be PS3.

In a multi-threaded application,

  • There may be many requirements added, and Power Manager is maintaining the highest state requested.

  • All the requirements of the higher power state must be removed for the M4 to transition to the next lower power state.

  • If multiple requirements are added, the state will change upon removing all the requirements.

Remove peripheral requirement#

If any peripheral is disabled in the PS4 state (for example, disabling SSI), upon switching to the PS2 state and then back to the PS4 state, all peripherals will be powered on during the state transition. The _sl_si91x_power_manager_remove_peripheral_requirement() can be used again to disable the required peripherals.

Measuring power consumption#

To measure the power consumption of only,

  • NWP - Configure M4 in PS0 without any RAM retention.

  • M4 - Configure NWP in DEEP_SLEEP_WITHOUT_RAM_RETENTION (Deep Sleep without RAM retention when the device is not associated with AP).