Apart from transitions in or out of Shutdown state through the BUCKEN pin, all transitions between Sleep and Active states are automatic and do not rely on any control pin assertion or de-assertion.
Shutdown state is achieved by de-assertion on the BUCKEN pin. Asserting BUCKEN will result in the Active (IDLE sub-state) state being entered. The host will initiate the boot sequence through Serial Peripheral Interface (SPI)/Quad Serial Peripheral Interface (QSPI), culminating in the Sleep state being entered. This is the lowest power non-Shutdown state that can be achieved. Transitions from Active to Sleep are fully controlled by nRF7002. Transitions from Sleep to Active are determined by both the host and nRF7002. In a pre-association condition, Sleep will be entered opportunistically whenever there is no activity initiated from the host (for example, a scan request). In a post-association condition, Sleep opportunities will be determined by the negotiated Power Save mode of the Access Point. No host interactions are required to enter Sleep, while the host will invoke a transition from Sleep to Active as part of any SPI/QSPI command transaction.
The steps used to transition from Shutdown or Sleep into Active are as follows:
The initial steps consume equal duration whether originating in Shutdown or Sleep, while the baseband and RF initializations are dependent on the originating state. In particular:
See Electrical specification for timing information.