System Requirements =================== This document contains high-level system requirements for the ESP32 Template project. .. req:: ESP32 Hardware Platform :id: REQ_SYS_HW_1 :status: approved :priority: mandatory :tags: hardware, platform **Description:** The system SHALL operate on ESP32 microcontroller with 4MB flash memory. **Rationale:** ESP32 provides WiFi connectivity, sufficient processing power, and adequate flash memory for IoT applications. **Acceptance Criteria:** * AC-1: System boots successfully on ESP32 WROOM-32 or compatible modules * AC-2: Flash usage does not exceed 90% of available 4MB * AC-3: System operates within ESP32 memory constraints (DRAM/IRAM) .. req:: WiFi Connectivity :id: REQ_SYS_NET_1 :status: approved :priority: mandatory :tags: network, wifi **Description:** The system SHALL provide WiFi connectivity in both Access Point (AP) and Station (STA) modes. **Rationale:** Enables web interface access and network configuration flexibility. **Acceptance Criteria:** * AC-1: System creates WiFi Access Point for initial configuration * AC-2: System connects to existing WiFi networks as station * AC-3: Automatic fallback to AP mode if STA connection fails .. req:: Web-based Configuration :id: REQ_SYS_WEB_1 :status: approved :priority: mandatory :tags: web, configuration :links: REQ_SYS_NET_1 **Description:** The system SHALL provide web interface for configuration and monitoring. **Rationale:** User-friendly interface for system setup and operation without firmware recompilation. **Acceptance Criteria:** * AC-1: Web interface accessible via HTTP * AC-2: Configuration changes applied without firmware recompilation * AC-3: Real-time monitoring of system status .. req:: Non-volatile Configuration Storage :id: REQ_SYS_CFG_1 :status: approved :priority: mandatory :tags: storage, nvs, configuration **Description:** The system SHALL persist configuration settings across power cycles using ESP32 NVS (Non-Volatile Storage). **Rationale:** Maintains user settings and system configuration permanently. **Acceptance Criteria:** * AC-1: Configuration survives device reset and power loss * AC-2: Factory reset capability restores default settings * AC-3: Configuration corruption detection and recovery .. req:: Component-based Architecture :id: REQ_SYS_ARCH_1 :status: approved :priority: mandatory :tags: architecture, modularity **Description:** The system SHALL implement modular component-based architecture following ESP-IDF conventions. **Rationale:** Enables maintainability, testability, and reusability. **Acceptance Criteria:** * AC-1: Components provide well-defined APIs * AC-2: Components are independently testable * AC-3: Main application coordinates components without tight coupling .. req:: Error Handling and Recovery :id: REQ_SYS_REL_1 :status: approved :priority: mandatory :tags: reliability, error-handling **Description:** The system SHALL handle errors gracefully and attempt recovery where possible. **Rationale:** Ensures system reliability and user experience. **Acceptance Criteria:** * AC-1: Component timeouts handled without system crash * AC-2: Network connection failures trigger automatic retry * AC-3: System logs errors for diagnostics * AC-4: Watchdog timer prevents system hang .. req:: Memory Management :id: REQ_SYS_PERF_1 :status: approved :priority: mandatory :tags: performance, memory **Description:** The system SHALL manage memory efficiently within ESP32 constraints. **Rationale:** Prevents memory leaks and ensures stable operation. **Acceptance Criteria:** * AC-1: Heap usage monitored and bounded * AC-2: No memory leaks during normal operation * AC-3: Stack overflow protection for all tasks * AC-4: Dynamic allocation minimized in time-critical paths .. req:: Emulator Support :id: REQ_SYS_SIM_1 :status: approved :priority: mandatory :tags: emulator, qemu, testing **Description:** The system SHALL support build-time selectable emulator mode (QEMU) that replaces hardware-specific modules with simulator implementations while preserving public APIs. **Rationale:** Enables development and testing without physical hardware, improves reproducibility and CI test coverage. **Acceptance Criteria:** * AC-1: Kconfig option ``CONFIG_TARGET_EMULATOR`` enables emulator builds * AC-2: Simulator implementations selected by CMake without requiring code changes * AC-3: Simulator components implement complete public API of hardware counterparts * AC-4: Emulator build runnable under QEMU with console output * AC-5: Documentation provides build/run verification steps .. req:: Emulator Network Connectivity :id: REQ_SYS_SIM_2 :status: approved :priority: optional :tags: emulator, qemu, network, development :links: REQ_SYS_SIM_1, REQ_SYS_NET_1 **Description:** The system SHOULD provide network connectivity when running in QEMU emulation to enable testing of network-dependent features. **Rationale:** Enables development and testing of web interfaces, WiFi configuration, and network protocols without physical ESP32 hardware. **Acceptance Criteria:** * AC-1: UART-based network tunnel bridges QEMU to host network stack * AC-2: Web interface accessible from host machine during emulation * AC-3: DHCP client obtains IP address in emulation mode * AC-4: Network features testable without hardware WiFi module * AC-5: Documentation describes emulation network setup and limitations Future Enhancements ------------------- .. req:: HTTPS Support :id: REQ_SYS_SEC_1 :status: open :priority: optional :tags: security, https, future **Description:** The system MAY support HTTPS for encrypted web interface communication. **Rationale:** Encrypted communication protects sensitive data (WiFi passwords, configuration) from network eavesdropping. However, embedded certificate management is complex. **Known Challenges:** * ESP32 flash constraints for certificate storage * Self-signed certificates trigger browser warnings * OTA updates complicate certificate lifecycle * QEMU emulation does not support HTTPS testing * Previous implementation attempts encountered stability issues **Acceptance Criteria (if implemented):** * AC-1: Web server supports both HTTP and HTTPS ports * AC-2: Self-signed certificate generated at build time or first boot * AC-3: Certificate embedded in flash or stored in NVS * AC-4: Browser security warnings documented for users * AC-5: Certificate renewal process defined for production deployments **Note:** This requirement is intentionally marked "open" due to complexity. For many embedded use cases, physical access security and network isolation provide sufficient protection. Production deployments requiring HTTPS should evaluate alternatives (VPN, mTLS, secure network). .. req:: System Time and NTP Support :id: REQ_SYS_TIME_1 :status: open :priority: optional :tags: time, ntp, future **Description:** The system MAY support network time synchronization via NTP for accurate timestamps. **Rationale:** Accurate system time enables timestamped logs, scheduled tasks, and time-based security features. Many IoT applications require synchronized time. **Acceptance Criteria (if implemented):** * AC-1: NTP client synchronizes with configurable NTP server * AC-2: Timezone configuration via web interface * AC-3: System time persists across reboots (RTC or NVS) * AC-4: Time synchronization status visible in web interface * AC-5: Fallback behavior defined if NTP unavailable **Note:** This requirement is marked "open" as template focuses on core functionality. Time synchronization can be added when application requires timestamped events or scheduling. Traceability ------------ All traceability is automatically generated by Sphinx-Needs based on the `:links:` attributes in each requirement. .. needtable:: :columns: id, title, status, tags .. needflow:: REQ_SYS_HW_1