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LED Controller Requirements

Document ID: REQ-LED-ESP32-DISTANCE
Version: 1.0
Date: 2025-09-16
Author: ESP32 Distance Project Team
Parent Document: SRS-ESP32-DISTANCE

Document Purpose

This document specifies the essential requirements for WS2812 LED strip control, focusing on user-facing functionality rather than implementation details.

Requirements Traceability

Requirement ID Design Reference Priority
REQ-LED-1 DSN-LED-ARCH-01, DSN-LED-TIMING-01 Mandatory
REQ-LED-2 DSN-LED-ARCH-02, DSN-LED-API-01, DSN-LED-API-02, DSN-LED-ERR-01 Mandatory
REQ-LED-3 DSN-LED-ARCH-02, DSN-LED-MEM-01, DSN-LED-ERR-01 Mandatory
REQ-LED-4 DSN-LED-API-02, DSN-LED-DATA-01 Mandatory

Dependencies:

  • REQ-LED-2 depends on REQ-LED-1 (cannot control pixels without hardware support)
  • REQ-LED-3 depends on REQ-LED-1 (LED count is hardware configuration parameter)
  • REQ-LED-4 depends on REQ-LED-2 (color accuracy requires pixel control)

Functional Requirements

REQ-LED-1: WS2812 LED Strip Support

Type: Functional
Priority: Mandatory
Description: The system SHALL support WS2812 addressable LED strips for visual distance display, providing hardware compatibility and initialization.

Rationale: WS2812 LEDs are the chosen hardware for distance visualization; system must interface with this specific LED technology.

Acceptance Criteria:

  • AC-1: System SHALL initialize WS2812 LED strips connected to configurable GPIO pin
  • AC-2: System SHALL support WS2812 timing and protocol requirements
  • AC-3: LEDs SHALL respond to control signals and display colors
  • AC-4: Initialization SHALL handle hardware configuration parameters

Verification: Connect WS2812 strip, verify LEDs respond to basic commands and display expected colors.

REQ-LED-2: Individual Pixel Control

Type: Functional
Priority: Mandatory
Description: The system SHALL provide the ability to set the color of individual LED pixels within the strip for precise distance visualization.

Rationale: Distance display requires lighting specific LEDs at calculated positions; individual control is essential for the application.

Acceptance Criteria:

  • AC-1: System SHALL set specific LED colors by index position
  • AC-2: Color control SHALL support RGB color space with 8-bit resolution per channel
  • AC-3: Individual LED changes SHALL NOT affect other LEDs
  • AC-4: System SHALL provide clear all LEDs functionality

Verification: Set individual LEDs to different colors, verify only targeted LEDs change, test clear all functionality.

REQ-LED-3: Configurable LED Count

Type: Functional
Priority: Mandatory
Description: The system SHALL support configurable LED strip lengths to accommodate different hardware deployments and installation requirements.

Rationale: Different installations may use varying LED strip lengths; system must be flexible for deployment scenarios.

Acceptance Criteria:

  • AC-1: LED count SHALL be configurable during system initialization
  • AC-2: System SHALL support LED counts from 1 to at least 100 LEDs
  • AC-3: System SHALL validate LED count parameters during configuration
  • AC-4: All LED positions within configured count SHALL be controllable

Verification: Test with different LED counts, verify all configured LEDs are controllable and out-of-range access is prevented.

REQ-LED-4: Accurate Color Display

Type: Quality
Priority: Mandatory
Description: The system SHALL display specified RGB colors accurately on WS2812 LEDs for reliable visual feedback to users.

Rationale: Color accuracy is essential for distance visualization effectiveness; users must be able to distinguish between different states (normal/error conditions).

Acceptance Criteria:

  • AC-1: Primary colors (red, green, blue) SHALL display distinctly and accurately
  • AC-2: White color SHALL appear as true white without color bias
  • AC-3: Black/off state SHALL turn LEDs completely off
  • AC-4: Color transitions SHALL be immediate when hardware is updated

Verification: Display primary colors and verify visual accuracy, test white balance and off state, measure color transition timing.