Display System Requirements

This document specifies requirements for the Display System, enabling visual representation of distance measurements through LED strip control with clear user experience definitions.

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

Overview

The display system provides visual feedback through WS2812 LED strips, showing current distance measurement with dual-layer architecture combining position indication and directional animation to guide optimal parking.

System Overview Requirements

Requirement: Hardware Platform REQ_DSP_1

status: approved tags: display, hardware, integration priority: mandatory links outgoing: REQ_LED_1, REQ_SYS_1 links incoming: US_DISPLAY_1, REQ_DSP_3, SPEC_DSP_OVERVIEW_1, API_COMP_DISPLAY_LOGIC, API_FUNC_DISPLAY_LOGIC_START

Description: The display system SHALL utilize WS2812 addressable LED strip hardware through the LED controller component API as an integrated, reactive component. LED count and brightness are configurable via configuration management system. Rationale: Establishes the hardware foundation for the visual display system, enabling flexible LED strip configurations for different deployment scenarios. The system operates reactively, automatically responding to distance measurements rather than external commands. Display system uses LED controller API for all hardware access, maintaining clear separation of concerns. Acceptance Criteria: AC-1: Display system uses LED controller component API for all LED hardware access AC-2: LED count and brightness are configurable via configuration management system AC-3: System validates LED count is within reasonable range (1-100 LEDs) AC-4: LED controller component handles all GPIO pin configuration and timing AC-5: Display system depends on LED controller initialization completing successfully AC-6: System operates continuously, updating display in real-time as measurements arrive

Requirement: Configuration Integration REQ_DSP_2

status: approved tags: display, configuration, integration priority: mandatory links outgoing: REQ_CFG_JSON_1, REQ_SYS_CFG_1 links incoming: US_DISPLAY_1, REQ_DSP_4, REQ_DSP_5, SPEC_DSP_ARCH_2, API_COMP_DISPLAY_LOGIC, API_FUNC_DISPLAY_LOGIC_START

Description: The display system SHALL obtain all operational parameters from the configuration management system. Rationale: Ensures centralized configuration management and eliminates hardcoded values, enabling runtime reconfiguration and consistent system behavior. Parameter validation is handled by the configuration manager. Configuration changes trigger system reset, allowing static memory allocation at startup with no runtime reallocation - preventing memory fragmentation and performance degradation in the embedded environment. Acceptance Criteria: AC-1: All display parameters are obtained from configuration manager AC-2: System reads configuration at initialization Configuration Parameters: led_count: Number of LEDs in the strip led_brightness: LED brightness level dist_min_mm: Minimum distance threshold (millimeters) dist_max_mm: Maximum distance threshold (millimeters)

User Experience Requirements

Requirement: Core Visualization Concept REQ_DSP_3

status: approved tags: display, ux, visualization priority: mandatory links outgoing: REQ_SNS_4, REQ_DSP_1 links incoming: US_DISPLAY_1, REQ_DSP_4, SPEC_DSP_ARCH_1, SPEC_DSP_ALGO_1, SPEC_DSP_API_1, API_COMP_DISPLAY_LOGIC, API_FUNC_DISPLAY_LOGIC_START

Description: The display system SHALL illuminate a single LED in green that represents the current measured distance with real-time updates. The display system consumes processed distance measurements from the distance sensor component without additional filtering or smoothing. Rationale: Provides clear, unambiguous visual feedback where users can immediately understand the current distance measurement through LED position. The distance sensor component owns all measurement processing, filtering, and smoothing (REQ_SNS_11); the display system is responsible solely for visual representation of processed measurements, maintaining clear separation of concerns. Acceptance Criteria: AC-1: Only one LED is illuminated at any given time AC-2: LED position corresponds to processed distance measurement value from sensor component AC-3: Display updates immediately when new processed measurements arrive from sensor queue AC-4: Display system SHALL NOT apply additional smoothing or filtering to distance measurements AC-5: Display system uses distance measurements directly from sensor component’s processed measurement queue

Requirement: Below Minimum Distance Warning REQ_DSP_4

status: approved tags: display, ux, safety priority: mandatory links outgoing: REQ_DSP_2, REQ_DSP_3 links incoming: US_DISPLAY_1, REQ_DSP_5, SPEC_DSP_ALGO_1, API_COMP_DISPLAY_LOGIC, API_FUNC_DISPLAY_LOGIC_START

Description: The display system SHALL illuminate the first LED (LED 0) in red when the measured distance is below the configured minimum distance threshold. Rationale: Red is universally recognized as a warning color. Illuminating the first LED in red when too close provides immediate, unmistakable indication of dangerous proximity. Acceptance Criteria: AC-1: LED 0 is illuminated red when distance < dist_min_mm AC-2: No green position indicator is shown (measurement invalid) AC-3: Display persists until measurement returns to valid range

Requirement: Out of Range Display REQ_DSP_5

status: approved tags: display, ux, error-handling priority: mandatory links outgoing: REQ_DSP_2, REQ_DSP_4 links incoming: US_DISPLAY_1, SPEC_DSP_ALGO_1

Description: the display SHALL iluminate the last LED (LED led_count-1) in red when the measured distance exceeds the configured maximum distance threshold, indicating out-of-range condition. Rationale: Red is universally recognized as an error/warning color. Illuminating the last LED in red when too far provides clear indication that the measurement is invalid and out of range. Acceptance Criteria: AC-1: last LED (LED led_count-1) is illuminated red when distance > dist_max_mm AC-2: No green position indicator is shown (measurement invalid) AC-3: Display persists until measurement returns to valid range

Traceability

ID	Title	Status	Links
REQ_DSP_1	Hardware Platform	approved	REQ_LED_1; REQ_SYS_1
REQ_DSP_2	Configuration Integration	approved	REQ_CFG_JSON_1; REQ_SYS_CFG_1
REQ_DSP_3	Core Visualization Concept	approved	REQ_SNS_4; REQ_DSP_1
REQ_DSP_4	Below Minimum Distance Warning	approved	REQ_DSP_2; REQ_DSP_3
REQ_DSP_5	Out of Range Display	approved	REQ_DSP_2; REQ_DSP_4