Abtin Keshavarzian
5c8c318627
This commit introduces a unified `ReceiveAt` abstraction in `SubMac` to handle timed reception windows (CSL receiver, WED / Thread-Direct wakeup listener) Motivation & Benefits: Previously, CSL sample window calculation and scheduling differed between platform-offloaded timing (`OT_RADIO_CAPS_RECEIVE_TIMING`) and stack-driven timing (`SubMac` software timers): - `GetCslWindowEdges()` added `kCslReceiveTimeAhead` lead time to the window margin, only for offloaded callers to manually subtract it back out before calling `Radio::ReceiveAt()`. - Stack-driven mode relied on separate timers for sample/sleep transitions (`HandleCslReceiveOrSleep`, `HandleWedReceiveOrSleep`), leading to code duplication and inconsistent timing margins across platform vs stack-driven executions. This commit harmonizes timed reception handling: - `GetCslWindowEdges()` cleanly computes target window bounds without caller-side adjustments. - `SubMac::ReceiveAt()` provides a single, consistent API for both offloaded and stack-driven timing. - Provides a clean foundation for Thread-Direct wakeup listening (WED) and future timed reception features. Key changes: - State Machine Refactoring: Simplifies the state management adding `kStateTimedReceive`. The radio state is `kStateTimedReceive` when actively receiving in a target rx window, and `kStateSleep` otherwise. - `TimedRx` Helper Class: Encapsulates window parameters (`mStartTime`, `mDuration`, `mChannel`) and state checks (`HasStarted`, `HasEnded`). - Pending & Active Window Preemption: `UpdateTimedRxState()` manages the timed RX schedules and sets the timer accordingly. It ensures pending windows starting before an active window ends are promoted seamlessly. - Unit Test: Adds a detailed `test_sub_mac_recv_at.cpp` covering various behaviors (including edge-cases) of `ReceiveAt()` logic.
What is OpenThread?
OpenThread released by Google is... 
...an open-source implementation of the Thread networking protocol. Google Nest has released OpenThread to make the technology used in Nest products more broadly available to developers to accelerate the development of products for the connected home.
...OS and platform agnostic, with a narrow platform abstraction layer and a small memory footprint, making it highly portable. It supports both system-on-chip (SoC) and network co-processor (NCP) designs.
...a Thread Certified Component, implementing all features defined in the Thread 1.4.0 specification, including all Thread networking layers (IPv6, 6LoWPAN, IEEE 802.15.4 with MAC security, Mesh Link Establishment, Mesh Routing) and device roles, as well as Border Router support.
More information about Thread can be found at threadgroup.org. Thread is a registered trademark of the Thread Group, Inc.
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Getting started
All end-user documentation and guides are located at openthread.io. If you're looking to do things like...
- Learn more about OpenThread features and enhancements
- Use OpenThread in your products
- Learn how to build and configure a Thread network
- Port OpenThread to a new platform
- Build an application on top of OpenThread
- Certify a product using OpenThread
...then openthread.io is the place for you.
Note: For users in China, end-user documentation is available at openthread.google.cn.
If you're interested in contributing to OpenThread, read on.
Contributing
We would love for you to contribute to OpenThread and help make it even better than it is today! See our Contributing Guidelines for more information.
Contributors are required to abide by our Code of Conduct and Coding Conventions and Style Guide.
License
OpenThread is released under the BSD 3-Clause license. See the LICENSE file for more information.
Please only use the OpenThread name and marks when accurately referencing this software distribution. Do not use the marks in a way that suggests you are endorsed by or otherwise affiliated with Nest, Google, or The Thread Group.
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