Startup Test Requirements
==========================

This document specifies requirements for the startup test sequence that provides visual feedback 
to users during system initialization, demonstrating hardware functionality and successful boot.

**Document Version**: 2.0  
**Last Updated**: 2025-11-12

Overview
--------

The startup test sequence provides immediate visual feedback during system boot, demonstrating 
that the device is initializing properly and all LEDs in the strip are functional.

Functional Requirements
-----------------------

.. req:: LED Controller Initialization
   :id: REQ_STARTUP_1
   :links: REQ_LED_1, REQ_SYS_1
   :status: approved
   :priority: mandatory
   :tags: startup, initialization, led

   **Description:** The system SHALL initialize the LED controller during startup before 
   performing the visual test sequence.

   **Rationale:** LED hardware must be ready before the startup sequence can execute.

   **Acceptance Criteria:**

   - AC-1: LED controller SHALL be initialized successfully during startup
   - AC-2: System SHALL proceed to visual sequence only after successful LED initialization

   **Verification:** Verify LED controller initializes without errors during system startup.

.. req:: Visual Boot Sequence
   :id: REQ_STARTUP_2
   :links: REQ_STARTUP_1, REQ_LED_2
   :status: approved
   :priority: mandatory
   :tags: startup, ux, validation

   **Description:** The system SHALL display a visual boot sequence by lighting LEDs in 
   sequential order from first to last, providing clear indication that the system is 
   initializing and all LEDs are functional.

   **Rationale:** Gives users immediate visual feedback that the device is booting properly and 
   demonstrates that all LEDs in the strip are working correctly.

   **Acceptance Criteria:**

   - AC-1: LEDs SHALL light sequentially from position 0 to position (led_count-1)
   - AC-2: Each LED SHALL display a distinct color during the sequence (e.g., blue or white)
   - AC-3: Test SHALL complete within reasonable time limits (example: 40 LEDs @ 50ms each = 2.0 second maximum)
   - AC-4: Each LED SHALL turn off before the next LED activates (single moving light pattern)
   - AC-5: Normal distance measurement SHALL begin after sequence completes

   **Verification:** Observe startup sequence, verify all LEDs activate in order with appropriate 
   timing and visual clarity.

Non-Functional Requirements
---------------------------

.. req:: Timing Performance
   :id: REQ_STARTUP_3
   :links: REQ_STARTUP_2
   :status: approved
   :priority: important
   :tags: startup, performance, timing

   **Description:** The startup test sequence SHALL complete within reasonable time limits to 
   avoid significantly delaying normal system operation.

   **Rationale:** Users expect reasonable boot times; startup test should provide value without 
   excessive delay.

   **Acceptance Criteria:**

   - AC-1: Complete startup sequence SHALL finish within 5 seconds for 60 LEDs
   - AC-2: LED activation timing SHALL be configurable (default 50ms per LED)
   - AC-3: Total startup delay SHALL not exceed 10 seconds regardless of LED count

   **Verification:** Measure startup sequence timing with different LED counts, verify 
   performance meets timing requirements.