# Feature Specification: Sensor Data Acquisition
# Feature ID: F-DAQ (F-DAQ-001 to F-DAQ-005)

**Document Type:** Feature Specification  
**Version:** 1.0  
**Date:** 2025-01-19  
**Feature Category:** Sensor Data Acquisition  

## 1. Feature Overview

### 1.1 Feature Purpose

The Sensor Data Acquisition feature provides comprehensive environmental sensor data collection, processing, and preparation capabilities for the ASF Sensor Hub. This feature ensures reliable, high-quality sensor data is available for persistence, communication, and system monitoring.

### 1.2 Feature Scope

**In Scope:**
- Multi-sensor data acquisition from 7 sensor types
- High-frequency sampling with configurable parameters
- Local data filtering and noise reduction
- Timestamped data record generation
- Sensor state management and lifecycle control

**Out of Scope:**
- Sensor hardware design and manufacturing
- Main Hub data processing and analytics
- Control algorithm implementation
- Actuator management

## 2. Sub-Features

### 2.1 F-DAQ-001: Multi-Sensor Data Acquisition

**Description:** Simultaneous data acquisition from multiple heterogeneous environmental sensors.

**Supported Sensor Types:**
- Temperature sensors (I2C/Analog)
- Humidity sensors (I2C)
- Carbon Dioxide (CO₂) sensors (UART/I2C)
- Ammonia (NH₃) sensors (Analog/I2C)
- Volatile Organic Compounds (VOC) sensors (I2C)
- Particulate Matter (PM) sensors (UART/I2C)
- Light Intensity sensors (Analog/I2C)

**Key Capabilities:**
- Concurrent sensor handling without blocking
- Modular sensor driver architecture
- Runtime sensor presence awareness
- Per-sensor enable/disable control

### 2.2 F-DAQ-002: High-Frequency Sampling

**Description:** Multiple raw readings per acquisition cycle with configurable sampling parameters.

**Sampling Characteristics:**
- Default: 10 samples per sensor per cycle
- Configurable sampling count (5-20 samples)
- Bounded sampling time window (max 800ms)
- Deterministic sampling intervals

**Benefits:**
- Noise reduction through oversampling
- Statistical confidence in measurements
- Outlier detection capability

### 2.3 F-DAQ-003: Local Data Filtering

**Description:** Configurable filtering algorithms applied to raw sensor samples.

**Available Filters:**
- **Median Filter:** Removes outliers and impulse noise
- **Moving Average:** Smooths data and reduces random noise
- **Rate-of-Change Limiter:** Prevents unrealistic value jumps

**Filter Configuration:**
- Filter type selectable per sensor
- Filter parameters configurable via Machine Constants
- Real-time filter switching capability

### 2.4 F-DAQ-004: Timestamped Data Generation

**Description:** Association of processed sensor values with accurate timestamps.

**Timestamp Characteristics:**
- Generated after filtering completion
- System time based (RTC or synchronized)
- Accuracy: ±1 second
- ISO 8601 format for persistence

**Data Record Structure:**
```c
typedef struct {
    uint8_t sensor_id;
    sensor_type_t sensor_type;
    float filtered_value;
    char unit[8];
    uint64_t timestamp_ms;
    data_validity_t validity;
    uint16_t sample_count;
    float raw_min, raw_max;
} sensor_data_record_t;
```

### 2.5 F-DAQ-005: Sensor State Management

**Description:** Comprehensive sensor lifecycle and state management.

**Sensor States:**
- **UNKNOWN:** Initial state, not yet detected
- **DETECTED:** Sensor presence confirmed
- **INITIALIZED:** Driver loaded and configured
- **ENABLED:** Active data acquisition
- **DISABLED:** Present but not acquiring data
- **FAULTY:** Detected failure condition
- **REMOVED:** Previously present, now absent

**State Transitions:**
```mermaid
stateDiagram-v2
    [*] --> UNKNOWN
    UNKNOWN --> DETECTED : Presence detected
    DETECTED --> INITIALIZED : Driver loaded
    INITIALIZED --> ENABLED : Acquisition started
    ENABLED --> DISABLED : Manual disable
    DISABLED --> ENABLED : Manual enable
    ENABLED --> FAULTY : Failure detected
    FAULTY --> ENABLED : Recovery successful
    DETECTED --> REMOVED : Presence lost
    INITIALIZED --> REMOVED : Presence lost
    ENABLED --> REMOVED : Presence lost
    DISABLED --> REMOVED : Presence lost
    FAULTY --> REMOVED : Presence lost
    REMOVED --> DETECTED : Presence restored
```

## 3. Requirements Coverage

### 3.1 System Requirements (SR-XXX)

| Feature | System Requirements | Description |
|---------|-------------------|-------------|
| **F-DAQ-001** | SR-DAQ-001 | Multi-sensor support for 7 sensor types |
| **F-DAQ-002** | SR-DAQ-002 | High-frequency sampling (min 10 samples/cycle) |
| **F-DAQ-003** | SR-DAQ-003 | Local data filtering with configurable algorithms |
| **F-DAQ-004** | SR-DAQ-004 | Timestamped data generation (±1 second accuracy) |
| **F-DAQ-005** | SR-DAQ-005 | Sensor state management and lifecycle control |

### 3.2 Software Requirements (SWR-XXX)

| Feature | Software Requirements | Implementation Details |
|---------|---------------------|----------------------|
| **F-DAQ-001** | SWR-DAQ-001, SWR-DAQ-002, SWR-DAQ-003 | Sensor driver abstraction, type enumeration, concurrent handling |
| **F-DAQ-002** | SWR-DAQ-004, SWR-DAQ-005, SWR-DAQ-006 | Configurable sampling, time windows, buffer management |
| **F-DAQ-003** | SWR-DAQ-007, SWR-DAQ-008, SWR-DAQ-009 | Median filter, moving average, filter selection |
| **F-DAQ-004** | SWR-DAQ-010, SWR-DAQ-011, SWR-DAQ-012 | Time interface, timestamp API, data record structure |
| **F-DAQ-005** | SWR-DAQ-013, SWR-DAQ-014, SWR-DAQ-015 | State enumeration, transition logic, persistence interface |

## 4. Component Implementation Mapping

### 4.1 Primary Components

| Component | Responsibility | Location |
|-----------|---------------|----------|
| **Sensor Manager** | Acquisition coordination, filtering, state management | `application_layer/business_stack/sensor_manager/` |
| **Sensor Drivers** | Hardware interface, raw data acquisition | `drivers/sensor_drivers/` |
| **Event System** | Data publication, component coordination | `application_layer/business_stack/event_system/` |
| **Data Pool** | Latest sensor data storage | `application_layer/DP_stack/data_pool/` |

### 4.2 Supporting Components

| Component | Support Role | Interface |
|-----------|-------------|-----------|
| **Time Utils** | Timestamp generation | `utils/time_utils/` |
| **Logger** | Debug and diagnostic logging | `utils/logger/` |
| **Machine Constant Manager** | Filter configuration, sensor parameters | `application_layer/business_stack/mc_manager/` |

### 4.3 Component Interaction Diagram

```mermaid
graph TB
    subgraph "Sensor Data Acquisition Feature"
        SM[Sensor Manager]
        SD[Sensor Drivers]
        ES[Event System]
        DP[Data Pool]
        TU[Time Utils]
        MCM[MC Manager]
    end
    
    subgraph "External Interfaces"
        SENSORS[Physical Sensors]
        PERSIST[Persistence]
        COMM[Communication]
    end
    
    SENSORS -->|I2C/SPI/UART/ADC| SD
    SD -->|Raw Samples| SM
    MCM -->|Filter Config| SM
    TU -->|Timestamp| SM
    SM -->|Filtered Data| ES
    ES -->|Data Update Event| DP
    ES -->|Data Update Event| PERSIST
    ES -->|Data Update Event| COMM
    
    SM -.->|State Changes| ES
    SM -.->|Diagnostics| ES
```

### 4.4 Data Flow Sequence

```mermaid
sequenceDiagram
    participant Sensor as Physical Sensor
    participant Driver as Sensor Driver
    participant Manager as Sensor Manager
    participant MCMgr as MC Manager
    participant TimeUtil as Time Utils
    participant EventSys as Event System
    participant DataPool as Data Pool
    
    Note over Sensor,DataPool: Acquisition Cycle (1 second)
    
    Manager->>MCMgr: getSamplingConfig(sensor_id)
    MCMgr-->>Manager: sampling_config
    
    loop 10 samples
        Manager->>Driver: readSensor(sensor_id)
        Driver->>Sensor: I2C/SPI/UART read
        Sensor-->>Driver: raw_value
        Driver-->>Manager: raw_sample
    end
    
    Manager->>Manager: applyFilter(raw_samples)
    Manager->>TimeUtil: getCurrentTimestamp()
    TimeUtil-->>Manager: timestamp
    
    Manager->>Manager: createDataRecord()
    Manager->>EventSys: publish(SENSOR_DATA_UPDATE, record)
    EventSys->>DataPool: updateSensorData(record)
    
    Note over Manager,DataPool: Data available for persistence and communication
```

## 5. Feature Behavior

### 5.1 Normal Operation Flow

1. **Initialization Phase:**
   - Load sensor configuration from Machine Constants
   - Initialize sensor drivers for detected sensors
   - Configure sampling and filtering parameters
   - Transition sensors to ENABLED state

2. **Acquisition Cycle (1 second):**
   - For each enabled sensor:
     - Perform high-frequency sampling (10 samples)
     - Apply configured filter to raw samples
     - Generate timestamp for filtered value
     - Create sensor data record
     - Publish data update event

3. **State Management:**
   - Monitor sensor health during acquisition
   - Detect and handle sensor failures
   - Update sensor states based on conditions
   - Report state changes via events

### 5.2 Error Handling

| Error Condition | Detection Method | Response Action |
|----------------|------------------|-----------------|
| **Sensor Communication Failure** | Timeout or invalid response | Mark sensor as FAULTY, continue with other sensors |
| **Out-of-Range Values** | Range validation | Mark data as invalid, log diagnostic event |
| **Sampling Timeout** | Bounded time window exceeded | Use partial samples, mark data quality degraded |
| **Filter Failure** | Exception in filter algorithm | Use raw average, log diagnostic event |
| **Memory Allocation Failure** | Buffer allocation failure | Skip cycle, trigger system diagnostic |

### 5.3 State-Dependent Behavior

| System State | Feature Behavior |
|-------------|------------------|
| **INIT** | Initialize sensors, load configuration |
| **RUNNING** | Normal acquisition cycles |
| **WARNING** | Continue acquisition, increase diagnostic reporting |
| **FAULT** | Stop acquisition, preserve sensor states |
| **OTA_UPDATE** | Stop acquisition, save sensor states |
| **MC_UPDATE** | Stop acquisition, reload configuration after update |
| **TEARDOWN** | Stop acquisition, flush pending data |
| **SERVICE** | Limited acquisition for diagnostics |
| **SD_DEGRADED** | Continue acquisition, no persistence |

## 6. Feature Constraints

### 6.1 Timing Constraints

- **Acquisition Cycle:** Must complete within 1 second
- **Sampling Window:** Maximum 800ms per sensor
- **Filter Processing:** Maximum 50ms per sensor
- **Event Publication:** Maximum 10ms delay

### 6.2 Resource Constraints

- **Memory Usage:** Maximum 32KB for sensor data buffers
- **CPU Usage:** Maximum 20% of available CPU time
- **I/O Bandwidth:** Shared among all sensors, priority-based

### 6.3 Quality Constraints

- **Data Accuracy:** Within sensor specification limits
- **Timestamp Accuracy:** ±1 second of system time
- **Filter Effectiveness:** >90% noise reduction for median filter
- **State Consistency:** 100% accurate state representation

## 7. Interface Specifications

### 7.1 Sensor Manager Public API

```c
// Initialization and configuration
bool sensorMgr_initialize(void);
bool sensorMgr_loadConfiguration(const machine_constants_t* mc);
bool sensorMgr_detectSensors(void);

// Acquisition control
bool sensorMgr_startAcquisition(void);
bool sensorMgr_stopAcquisition(void);
bool sensorMgr_pauseAcquisition(void);
bool sensorMgr_resumeAcquisition(void);

// Sensor control
bool sensorMgr_enableSensor(uint8_t sensor_id);
bool sensorMgr_disableSensor(uint8_t sensor_id);
bool sensorMgr_configureSensor(uint8_t sensor_id, const sensor_config_t* config);

// Data access
bool sensorMgr_getLatestData(uint8_t sensor_id, sensor_data_record_t* record);
bool sensorMgr_getAllSensorData(sensor_data_record_t* records, size_t* count);

// State management
sensor_state_t sensorMgr_getSensorState(uint8_t sensor_id);
bool sensorMgr_isSensorPresent(uint8_t sensor_id);
bool sensorMgr_isSensorEnabled(uint8_t sensor_id);
bool sensorMgr_isSensorHealthy(uint8_t sensor_id);

// Statistics and diagnostics
bool sensorMgr_getSensorStatistics(uint8_t sensor_id, sensor_stats_t* stats);
bool sensorMgr_resetSensorStatistics(uint8_t sensor_id);
```

### 7.2 Event System Integration

**Published Events:**
- `EVENT_SENSOR_DATA_UPDATE`: New sensor data available
- `EVENT_SENSOR_STATE_CHANGED`: Sensor state transition
- `EVENT_SENSOR_FAULT_DETECTED`: Sensor failure detected
- `EVENT_SENSOR_RECOVERY`: Sensor recovered from fault

**Subscribed Events:**
- `EVENT_STATE_CHANGED`: System state transitions
- `EVENT_MC_UPDATED`: Machine constants updated
- `EVENT_TEARDOWN_INITIATED`: System teardown requested

### 7.3 Data Pool Integration

**Data Storage:**
- Latest sensor data records for all sensors
- Sensor state information
- Acquisition statistics and health metrics

**Access Patterns:**
- Write: Sensor Manager updates after each acquisition cycle
- Read: Communication and Persistence components access latest data
- Query: HMI and Diagnostics access for display and analysis

## 8. Testing and Validation

### 8.1 Unit Testing

- **Sensor Driver Interface:** Mock sensors for driver testing
- **Filtering Algorithms:** Known input/output validation
- **State Machine:** All state transitions and edge cases
- **Data Record Generation:** Structure and content validation

### 8.2 Integration Testing

- **Sensor Manager + Drivers:** Real sensor hardware testing
- **Event System Integration:** Event publication and subscription
- **Data Pool Integration:** Data storage and retrieval
- **State Management:** Cross-component state coordination

### 8.3 System Testing

- **Multi-Sensor Acquisition:** All 7 sensor types simultaneously
- **Performance Testing:** Timing constraints under load
- **Fault Injection:** Sensor failure scenarios
- **Long-Duration Testing:** 24-hour continuous operation

### 8.4 Acceptance Criteria

- All sensor types successfully detected and initialized
- Acquisition cycles complete within 1-second constraint
- Filter algorithms reduce noise by >90%
- State transitions occur correctly under all conditions
- No memory leaks during continuous operation
- Graceful handling of all error conditions

## 9. Dependencies

### 9.1 Internal Dependencies

- **Machine Constant Manager:** Sensor configuration and parameters
- **Event System:** Inter-component communication
- **Data Pool:** Data storage and access
- **Time Utils:** Timestamp generation
- **Logger:** Debug and diagnostic output

### 9.2 External Dependencies

- **ESP-IDF Framework:** Hardware abstraction and drivers
- **FreeRTOS:** Task scheduling and timing
- **Hardware Sensors:** Physical sensor devices
- **System State Manager:** State-aware operation control

## 10. Future Enhancements

### 10.1 Planned Improvements

- **Adaptive Filtering:** Machine learning-based filter optimization
- **Predictive Maintenance:** Sensor degradation prediction
- **Advanced Calibration:** Multi-point calibration support
- **Sensor Fusion:** Cross-sensor validation and fusion

### 10.2 Scalability Considerations

- **Additional Sensor Types:** Framework supports easy extension
- **Higher Sampling Rates:** Configurable for future requirements
- **Distributed Processing:** Support for sensor processing offload
- **Cloud Integration:** Direct sensor data streaming capability

---

**Document Status:** Final for Implementation Phase  
**Component Dependencies:** Verified against architecture  
**Requirements Traceability:** Complete (45 SR, 122 SWR)  
**Next Review:** After component implementation