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ASF Sensor Hub – Feature Definition Document
(Global, Feature-Based, Architecture-Neutral)
This document defines the system features of the ASF Sensor Hub subsystem, organized by functional categories. It is intended to be used as:
- A feature baseline in ALM
- Input to system requirements derivation
- Reference for architecture and software design
- Traceability anchor to IEC 61508 / IEC 61499 style decomposition later
⚠️ Important Scope Note This document covers ONLY the Sensor Hub (Sub-Hub) based on ESP32-S3. Main Hub, Cloud, Farm Control Logic are explicitly out of scope.
1. System Context Overview
The ASF Sensor Hub is a distributed sensing node deployed inside a poultry house. Its primary responsibilities are:
- Acquisition of multiple environmental sensors
- Local preprocessing and validation of sensor data
- Persistent storage of data and configuration
- Secure communication with a Main Hub
- Support for diagnostics, maintenance, and OTA updates
- Safe operation under fault conditions
The Sensor Hub operates as an autonomous embedded system with defined lifecycle states.
2. Feature Categorization Overview
The system features are grouped into the following categories:
- Sensor Data Acquisition Features
- Data Quality & Calibration Features
- Communication Features
- Diagnostics & Health Monitoring Features
- Persistence & Data Management Features
- Firmware Update (OTA) Features
- Security & Safety Features
- System Management Features
Each feature is described at a functional level (WHAT the system does, not HOW).
3. Sensor Data Acquisition Features
F-DAQ-01: Multi-Sensor Data Acquisition
The system provides the capability to acquire data from multiple environmental sensors connected to the Sensor Hub hardware.
Supported sensor types include:
- Temperature
- Humidity
- Carbon Dioxide (CO₂)
- Ammonia (NH₃)
- Volatile Organic Compounds (VOC)
- Particulate Matter (PM)
- Light Intensity
F-DAQ-02: High-Frequency Sampling and Local Filtering
The system provides local preprocessing of sensor data by:
- Sampling each sensor multiple times per acquisition cycle
- Applying a fast local filtering mechanism
- Producing a single validated value per sensor per cycle
Filtering algorithms are pluggable and configurable.
F-DAQ-03: Timestamped Sensor Data Generation
The system provides timestamped sensor data using a synchronized local time source.
Each sensor record includes:
- Sensor identifier
- Measured value
- Timestamp
- Data validity status
4. Data Quality & Calibration Features
F-DQC-01: Automatic Sensor Detection
The system provides automatic detection of sensor presence based on dedicated hardware detection signals.
Key characteristics:
- Each sensor slot is type-specific
- Sensor presence is detected during initialization and runtime
- Only detected sensors are initialized and sampled
F-DQC-02: Sensor Type Enforcement
The system enforces sensor-slot compatibility to prevent incorrect sensor usage.
Each physical slot:
- Accepts only one sensor type
- Is mapped to a predefined sensor class in software
F-DQC-03: Sensor Failure Detection
The system provides detection of sensor failures, including:
- Communication errors
- Out-of-range values
- Non-responsive sensors
Detected failures are classified and reported.
F-DQC-04: Machine Constants & Calibration Management
The system provides a Machine Constants (MC) mechanism responsible for:
- Defining installed sensor types
- Holding sensor calibration parameters
- Defining communication parameters
- Defining system identity parameters
MC data is persistent and reloadable.
5. Communication Features
F-COM-01: Main Hub Communication
The system provides bidirectional communication with a Main Hub to:
- Send sensor data
- Send diagnostics information
- Receive configuration updates
- Receive firmware updates
F-COM-02: On-Demand Data Broadcasting
The system provides on-demand transmission of the most recent sensor dataset upon request from the Main Hub.
F-COM-03: Peer Sensor Hub Communication
The system provides limited peer-to-peer communication between Sensor Hubs for:
- Connectivity checks
- Time synchronization support
- Basic status exchange
This feature is on-demand and optional.
6. Diagnostics & Health Monitoring Features
F-DIAG-01: Diagnostic Code Management
The system provides structured diagnostics with:
- Diagnostic codes
- Severity levels
- Root cause hierarchy
- Timestamping
F-DIAG-02: Diagnostic Data Storage
The system provides persistent storage of diagnostic events for post-analysis.
F-DIAG-03: Diagnostic Session
The system provides a diagnostic session allowing engineers to:
- Retrieve diagnostic data
- Inspect system health
- Clear diagnostic records
7. Persistence & Data Management Features
F-DATA-01: Persistent Sensor Data Storage
The system provides persistent storage of sensor data in non-volatile memory (SD Card).
F-DATA-02: Data Persistence Abstraction (DP Component)
The system provides a Data Persistence (DP) component responsible for:
- Abstracting storage media (SD / NVM)
- Managing write/read operations
- Ensuring data integrity
F-DATA-03: Safe Data Handling During State Transitions
The system ensures that all critical data is safely stored before:
- Firmware update
- Configuration update
- System teardown
- Reset or restart
8. Firmware Update (OTA) Features
F-OTA-01: OTA Update Negotiation
The system provides an OTA handshake mechanism with the Main Hub to:
- Acknowledge update availability
- Signal readiness for update
F-OTA-02: Firmware Reception and Storage
The system provides secure reception of firmware images and temporary storage on SD Card.
F-OTA-03: Firmware Integrity Validation
The system validates firmware integrity using checksum or CRC before activation.
F-OTA-04: Safe Firmware Activation
The system provides controlled firmware flashing and rollback-safe activation.
9. Security & Safety Features
F-SEC-01: Secure Boot
The system provides secure boot functionality to ensure only authenticated firmware is executed.
F-SEC-02: Secure Flash Storage
The system provides encrypted flash storage for sensitive assets.
F-SEC-03: Encrypted Communication
The system provides encrypted communication channels for all external data exchange.
10. System Management Features
F-SYS-01: System State Management
The system provides explicit lifecycle states including:
- Initialization
- Normal Operation
- Degraded Operation
- Update Mode
- Fault Mode
- Teardown Mode
F-SYS-02: Controlled Teardown Mechanism
The system provides a controlled teardown mechanism that:
- Stops sensor acquisition
- Flushes all critical data
- Ensures persistent storage consistency
- Prepares the system for update or shutdown
F-SYS-03: Status Indication
The system provides visual status indicators:
- Green: Normal operation
- Yellow: Warning state
- Red: Fatal error state
F-SYS-04: Debug & Engineering Sessions
The system provides engineering access sessions allowing:
- Log inspection
- MC file inspection and update
- Command execution
- Controlled debugging
11. Feature Relationship Overview (High-Level)
Sensor Acquisition
↓
Data Quality & Calibration
↓
Data Persistence
↓
Communication
↓
Diagnostics & System Management
↓
OTA / Security / Safety
-
Machine Constants affect:
- Sensor initialization
- Calibration
- Communication
-
Diagnostics span all features
-
Teardown is a cross-cutting mechanism triggered by:
- OTA
- MC update
- Fatal faults