CSS Configuration#

For more detailed information about CSS and its power profiles, see the Amazon Sidewalk specification

Typical Behavior#

CSS is an asynchronous protocol, which means it does not keep a connection with the gateway. Listening windows for reception can be every 5 seconds indefinitely or for a limited time after a transmission, as shown in the following example.

Amazon Sidewalk - CSSAmazon Sidewalk - CSS

Without any transmission from the endpoint in the last 5 minutes, the gateway considers the endpoint inactive and stops sending messages. Depending on the power profile, the keep-alive mechanism is handled by the application or the Sidewalk stack.

Power Consumption and Energy Modes#

CSS Power Profiles#

Power profile A only opens listening windows after a transmission. The application is responsible for keeping the connection with the gateway alive. Power profile B opens listening windows periodically while also assuring regular transmission to keep the connection alive. In the sub-GHz Hello Neighbor application, power profile B is the default.

Possible Parameters#

The CSS power profile can be modified by the sid_option API call using option SID_OPTION_900MHZ_SET_DEVICE_PROFILE. Then the structure sid_device_profile_unicast_params can be updated with the following values:

  • The device profile ID possible values SID_LINK3_PROFILE_A and SID_LINK3_PROFILE_B contained in sid_device_profile_id enum.

  • The number of RX windows is either SID_RX_WINDOW_CNT_INFINITE for power profile A and any of the other values in enum sid_rx_window_count for power profile B.

  • The windows separation can be any of the values of enum sid_link3_rx_window_separation_ms.

  • Values for the type of event for which the device wakes up are contained in enum sid_unicast_wakeup_type.