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Introduction
174
SWRU455A – February 2017 – Revised March 2017
Copyright © 2017, Texas Instruments Incorporated
Rx Filters
11.1 Introduction
The Rx filter is a powerful feature which 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 filters are organized in a tree structure, and the tree traversal is from the root to the leaf. The
maximum number of supported filters is 64; 15 filters are used by the SimpleLink Wi-Fi device and have
no access from the host, and 49 filters are available for the host to use.
The host interface includes the following operations:
•
Create filter
•
Update filter arguments
•
Enable filters; the function enables several filters at once
•
Disable filters; the function disables several filters at once
•
Remove filters; the function deletes several filters at once
•
Store filters; the function stores all the filters on the FS
describes the processing of the Rx filters in high level.