SWRU455M February 2017 – October 2020 CC3120 , CC3120MOD , CC3130 , CC3135 , CC3135MOD , CC3220MOD , CC3220MODA , CC3220R , CC3220S , CC3220SF , CC3230S , CC3230SF , CC3235MODAS , CC3235MODASF , CC3235MODS , CC3235MODSF , CC3235S , CC3235SF
The Rx filter is a powerful feature that enables the host to save power consumption and reduce application code.
The host can define reception filters that have been processed by the device. Each frame is tested against the filters; if there is a match, the filter actions are executed. Filter actions can be set to drop the frame or send an event to the host.
The Rx filters can be used for implementing features such as Wake on LAN, in which the host can enter deep sleep until a specific frame is detected by the device, then wake up the host by sending the programmed event.
The Rx filter feature can filter frames by standard protocol fields of a frame (MAC, frame type, IP, and so forth), or by pattern on the frame payload.
The Rx filters are rule-based systems embedded in the SimpleLink Wi-Fi device. They let the user simply define a set of filters that determine which of the received frames will be dropped by the SimpleLink Wi-Fi device. They also let the user configure filters that trigger asynchronous events to the host.
Operating the Rx filter with the event mechanism can reduce the power consumption and code size of the host MCU. Using filters can also reduce the processing efforts of the SimpleLink Wi-Fi device itself, because frames can be dropped before their processing is finished.
The maximum number of supported filters is 64; 15 filters are used by the SimpleLink Wi-Fi device and cannot be configured or viewed from the host, and 49 filters are configurable by the host.
The host interface includes the following operations:
Figure 12-1 describes the processing of the Rx filters at a high level.
The Rx filter module includes a database of filters, an interface for defining the filters from the host, a match process, and execution of actions.