Merge pull request #8 from mlp6/copilot/add-sequence-diagrams

Add sequence diagrams to Zephyr Threads & Kernel Events lecture and lab

Author: mlp6

labs/zephyr-threads-events-lab.qmd

@@ -77,6 +77,20 @@ to verify that your refactored code still works as expected.
 working with regard to what data to collect, how to analyze it, and how to
 present it in your notebook.
 
+## Create a Sequence Diagram
+
+- Create a [PlantUML](https://plantuml.com/sequence-diagram) sequence diagram
+that documents the interaction between your button ISR callback(s), the kernel
+event bit array, and your state machine thread when a button press event is
+detected and processed.
+
+- Your sequence diagram should show all relevant participants and the
+chronological order of messages between them (refer to the sequence diagram
+covered in the Threads & Kernel Events lecture).
+
+- Commit both the PlantUML source file (`.puml`) and the rendered image to your
+repository under a `docs/` directory.
+
 ### Merge-n-Tag this Refactored Kernel Events Code and Analysis
 
 - Create a Merge Request to merge `kernel_events_refactor` into your `main`

slides/zephyr-threads-events.qmd

@@ -162,8 +162,49 @@ extern void temp_too_high_thread(void *, void *, void *) {
 }
 ```
 
+## Sequence Diagrams for Thread Communication
+
+- Sequence diagrams visualize how components **interact over time**.
+
+- Useful for documenting the flow of messages between threads, ISR callbacks,
+and kernel services.
+
+- Participants in a Zephyr firmware application may include:
+
+  - Threads (e.g., `main`, worker threads)
+
+  - ISR Callbacks
+
+  - Kernel Event Bit Arrays
+
+  - Kernel Timers
+
+## PlantUML Sequence Diagram Example
+
+```plantuml
+@startuml
+
+participant "Button ISR\nCallback" as ISR
+participant "Kernel Event\nBit Array" as KEvents
+participant "Worker Thread" as Worker
+
+Worker -> KEvents : k_event_wait()\n[blocking]
+activate Worker #LightBlue
+
+note over ISR : Button Pressed
+ISR -> KEvents : k_event_post(BUTTON_EVENT)
+KEvents --> Worker : BUTTON_EVENT received
+deactivate Worker
+
+Worker -> Worker : process event\n(e.g., change state)
+
+@enduml
+```
+
 ## Resources
 
 - [Nordic DevAcademy: Zephyr RTOS Advanced](https://academy.nordicsemi.com/courses/nrf-connect-sdk-intermediate/lessons/lesson-1-zephyr-rtos-advanced/)
 
-- [Zephyr Documentation: Events](https://docs.zephyrproject.org/latest/kernel/services/synchronization/events.html#events)
+- [Zephyr Documentation: Events](https://docs.zephyrproject.org/latest/kernel/services/synchronization/events.html#events)
+
+- [PlantUML: Sequence Diagrams](https://plantuml.com/sequence-diagram)