# Feature Specification: Hardware Abstraction
# Feature ID: F-HW (F-HW-001 to F-HW-002)

**Document Type:** Feature Specification  
**Version:** 1.0  
**Date:** 2025-01-19  
**Feature Category:** Hardware Abstraction  

## 1. Feature Overview

### 1.1 Feature Purpose

The Hardware Abstraction feature provides a clean separation between application logic and hardware interfaces for the ASF Sensor Hub. This feature ensures hardware independence, maintainability, and testability by abstracting all hardware access through well-defined interfaces and preventing direct hardware access from the application layer.

### 1.2 Feature Scope

**In Scope:**
- Sensor Abstraction Layer (SAL) for uniform sensor access
- Hardware interface abstraction for I2C, SPI, UART, ADC, GPIO
- Storage interface abstraction for SD Card and NVM
- Display and user interface abstraction
- GPIO discipline enforcement and resource conflict detection

**Out of Scope:**
- Hardware driver implementation details (delegated to ESP-IDF)
- Hardware-specific performance optimizations
- Physical hardware design and pin assignments
- Low-level hardware debugging interfaces

## 2. Sub-Features

### 2.1 F-HW-001: Sensor Abstraction Layer (SAL)

**Description:** Comprehensive sensor abstraction layer providing uniform access to all sensor types while maintaining hardware independence and enabling runtime sensor management.

**Sensor Abstraction Interface:**
```c
typedef struct {
    uint8_t sensor_id;               // Unique sensor identifier
    sensor_type_t type;              // Sensor type enumeration
    char name[32];                   // Human-readable sensor name
    char unit[8];                    // Measurement unit (°C, %, ppm, etc.)
    float min_value;                 // Minimum valid measurement
    float max_value;                 // Maximum valid measurement
    float accuracy;                  // Sensor accuracy specification
    uint32_t warmup_time_ms;         // Required warmup time
    uint32_t sampling_interval_ms;   // Minimum sampling interval
    sensor_interface_t interface;    // Hardware interface type
} sensor_metadata_t;

typedef enum {
    SENSOR_TYPE_TEMPERATURE = 0,     // Temperature sensors
    SENSOR_TYPE_HUMIDITY = 1,        // Humidity sensors
    SENSOR_TYPE_CO2 = 2,            // Carbon dioxide sensors
    SENSOR_TYPE_AMMONIA = 3,        // Ammonia sensors
    SENSOR_TYPE_VOC = 4,            // Volatile organic compounds
    SENSOR_TYPE_LIGHT = 5,          // Light intensity sensors
    SENSOR_TYPE_PARTICULATE = 6     // Particulate matter sensors
} sensor_type_t;

typedef enum {
    SENSOR_INTERFACE_I2C = 0,       // I2C interface
    SENSOR_INTERFACE_SPI = 1,       // SPI interface
    SENSOR_INTERFACE_UART = 2,      // UART interface
    SENSOR_INTERFACE_ADC = 3,       // Analog ADC interface
    SENSOR_INTERFACE_GPIO = 4       // Digital GPIO interface
} sensor_interface_t;
```

**Sensor State Management:**
```c
typedef enum {
    SENSOR_STATE_UNKNOWN = 0,       // Initial state, not detected
    SENSOR_STATE_DETECTED = 1,      // Presence confirmed
    SENSOR_STATE_INITIALIZED = 2,   // Driver loaded and configured
    SENSOR_STATE_WARMUP = 3,        // Warming up, not stable
    SENSOR_STATE_STABLE = 4,        // Operational and stable
    SENSOR_STATE_ENABLED = 5,       // Active data acquisition
    SENSOR_STATE_DISABLED = 6,      // Present but not acquiring
    SENSOR_STATE_DEGRADED = 7,      // Operational but degraded
    SENSOR_STATE_FAULTY = 8,        // Detected failure condition
    SENSOR_STATE_REMOVED = 9        // Previously present, now absent
} sensor_state_t;

typedef struct {
    sensor_state_t current_state;    // Current sensor state
    sensor_state_t previous_state;   // Previous sensor state
    uint64_t state_change_time;      // Last state change timestamp
    uint32_t state_change_count;     // Total state changes
    uint32_t fault_count;            // Number of faults detected
    uint32_t recovery_count;         // Number of successful recoveries
    float last_valid_reading;        // Last known good reading
    uint64_t last_reading_time;      // Timestamp of last reading
} sensor_state_info_t;
```

**Sensor State Machine:**
```mermaid
stateDiagram-v2
    [*] --> UNKNOWN
    UNKNOWN --> DETECTED : Presence detected
    DETECTED --> INITIALIZED : Driver loaded
    INITIALIZED --> WARMUP : Acquisition started
    WARMUP --> STABLE : Warmup complete
    STABLE --> ENABLED : Enable command
    ENABLED --> DISABLED : Disable command
    DISABLED --> ENABLED : Enable command
    ENABLED --> DEGRADED : Performance degradation
    DEGRADED --> ENABLED : Performance restored
    ENABLED --> FAULTY : Failure detected
    DEGRADED --> FAULTY : Failure detected
    FAULTY --> ENABLED : Recovery successful
    FAULTY --> REMOVED : Hardware removed
    ENABLED --> REMOVED : Hardware removed
    DISABLED --> REMOVED : Hardware removed
    DEGRADED --> REMOVED : Hardware removed
    REMOVED --> DETECTED : Hardware restored
```

**Uniform Sensor API:**
```c
// Sensor lifecycle management
bool sal_initializeSensor(uint8_t sensor_id);
bool sal_enableSensor(uint8_t sensor_id);
bool sal_disableSensor(uint8_t sensor_id);
bool sal_resetSensor(uint8_t sensor_id);

// Sensor data operations
bool sal_readSensor(uint8_t sensor_id, float* value);
bool sal_calibrateSensor(uint8_t sensor_id, const calibration_data_t* cal_data);
bool sal_validateReading(uint8_t sensor_id, float value);
bool sal_performHealthCheck(uint8_t sensor_id);

// Sensor information and status
bool sal_getSensorMetadata(uint8_t sensor_id, sensor_metadata_t* metadata);
sensor_state_t sal_getSensorState(uint8_t sensor_id);
bool sal_getSensorStateInfo(uint8_t sensor_id, sensor_state_info_t* info);
bool sal_isSensorPresent(uint8_t sensor_id);
bool sal_isSensorHealthy(uint8_t sensor_id);
```

**Sensor Driver Interface:**
```c
typedef struct {
    // Driver identification
    char driver_name[32];            // Driver name
    char driver_version[16];         // Driver version
    sensor_type_t supported_type;    // Supported sensor type
    
    // Driver operations
    bool (*initialize)(uint8_t sensor_id);
    bool (*read_raw)(uint8_t sensor_id, uint32_t* raw_value);
    bool (*convert_value)(uint32_t raw_value, float* converted_value);
    bool (*calibrate)(uint8_t sensor_id, const calibration_data_t* cal_data);
    bool (*health_check)(uint8_t sensor_id);
    bool (*reset)(uint8_t sensor_id);
    
    // Driver configuration
    sensor_metadata_t metadata;     // Sensor metadata
    void* driver_config;            // Driver-specific configuration
} sensor_driver_interface_t;
```

### 2.2 F-HW-002: Hardware Interface Abstraction

**Description:** Comprehensive abstraction of all hardware interfaces to prevent direct hardware access from the application layer and ensure consistent interface usage across the system.

**GPIO Discipline and Management:**
```c
typedef struct {
    uint8_t gpio_number;            // Physical GPIO pin number
    gpio_function_t function;       // Assigned function
    gpio_direction_t direction;     // Input/Output direction
    gpio_pull_t pull_config;        // Pull-up/Pull-down configuration
    bool is_strapping_pin;          // Strapping pin flag
    bool is_reserved;               // Reserved for system use
    char assigned_component[32];    // Component using this GPIO
} gpio_pin_config_t;

typedef enum {
    GPIO_FUNC_UNUSED = 0,           // Pin not used
    GPIO_FUNC_I2C_SDA = 1,         // I2C data line
    GPIO_FUNC_I2C_SCL = 2,         // I2C clock line
    GPIO_FUNC_SPI_MOSI = 3,        // SPI master out, slave in
    GPIO_FUNC_SPI_MISO = 4,        // SPI master in, slave out
    GPIO_FUNC_SPI_CLK = 5,         // SPI clock
    GPIO_FUNC_SPI_CS = 6,          // SPI chip select
    GPIO_FUNC_UART_TX = 7,         // UART transmit
    GPIO_FUNC_UART_RX = 8,         // UART receive
    GPIO_FUNC_ADC_INPUT = 9,       // ADC analog input
    GPIO_FUNC_DIGITAL_INPUT = 10,  // Digital input
    GPIO_FUNC_DIGITAL_OUTPUT = 11, // Digital output
    GPIO_FUNC_PWM_OUTPUT = 12      // PWM output
} gpio_function_t;

// Strapping pins that must be avoided for general-purpose I/O
#define GPIO_STRAPPING_PINS {0, 3, 45, 46}
```

**I2C Interface Abstraction:**
```c
typedef struct {
    uint8_t i2c_port;               // I2C port number (0 or 1)
    uint8_t sda_pin;                // SDA pin assignment
    uint8_t scl_pin;                // SCL pin assignment
    uint32_t frequency_hz;          // I2C frequency (100kHz, 400kHz)
    bool pullup_enabled;            // Internal pull-up enable
    uint32_t timeout_ms;            // Transaction timeout
} i2c_config_t;

// I2C abstraction API
bool hw_i2c_initialize(uint8_t port, const i2c_config_t* config);
bool hw_i2c_write(uint8_t port, uint8_t device_addr, const uint8_t* data, size_t len);
bool hw_i2c_read(uint8_t port, uint8_t device_addr, uint8_t* data, size_t len);
bool hw_i2c_write_read(uint8_t port, uint8_t device_addr, 
                      const uint8_t* write_data, size_t write_len,
                      uint8_t* read_data, size_t read_len);
bool hw_i2c_scan_devices(uint8_t port, uint8_t* found_devices, size_t* count);
```

**SPI Interface Abstraction:**
```c
typedef struct {
    uint8_t spi_host;               // SPI host (SPI2_HOST, SPI3_HOST)
    uint8_t mosi_pin;               // MOSI pin assignment
    uint8_t miso_pin;               // MISO pin assignment
    uint8_t sclk_pin;               // Clock pin assignment
    uint8_t cs_pin;                 // Chip select pin
    uint32_t frequency_hz;          // SPI frequency
    uint8_t mode;                   // SPI mode (0-3)
    uint8_t bit_order;              // MSB/LSB first
} spi_config_t;

// SPI abstraction API
bool hw_spi_initialize(uint8_t host, const spi_config_t* config);
bool hw_spi_transmit(uint8_t host, const uint8_t* tx_data, size_t len);
bool hw_spi_receive(uint8_t host, uint8_t* rx_data, size_t len);
bool hw_spi_transmit_receive(uint8_t host, const uint8_t* tx_data, 
                            uint8_t* rx_data, size_t len);
```

**ADC Interface Abstraction:**
```c
typedef struct {
    adc_unit_t adc_unit;            // ADC1 or ADC2 (ADC1 only when Wi-Fi active)
    adc_channel_t channel;          // ADC channel
    adc_atten_t attenuation;        // Input attenuation
    adc_bitwidth_t resolution;      // ADC resolution
    uint32_t sample_count;          // Samples for averaging
} adc_config_t;

// ADC abstraction API
bool hw_adc_initialize(const adc_config_t* config);
bool hw_adc_read_raw(adc_unit_t unit, adc_channel_t channel, uint32_t* raw_value);
bool hw_adc_read_voltage(adc_unit_t unit, adc_channel_t channel, float* voltage);
bool hw_adc_calibrate(adc_unit_t unit, adc_channel_t channel);
```

**Storage Interface Abstraction:**
```c
// SD Card abstraction
typedef struct {
    uint8_t mosi_pin;               // SD card MOSI pin
    uint8_t miso_pin;               // SD card MISO pin
    uint8_t clk_pin;                // SD card clock pin
    uint8_t cs_pin;                 // SD card chip select pin
    uint32_t frequency_hz;          // SD card SPI frequency
    bool format_if_mount_failed;    // Auto-format on mount failure
} sd_card_config_t;

bool hw_sd_initialize(const sd_card_config_t* config);
bool hw_sd_mount(const char* mount_point);
bool hw_sd_unmount(void);
bool hw_sd_get_info(sd_card_info_t* info);

// NVM (NVS) abstraction
bool hw_nvs_initialize(void);
bool hw_nvs_write_blob(const char* namespace, const char* key, 
                      const void* data, size_t size);
bool hw_nvs_read_blob(const char* namespace, const char* key, 
                     void* data, size_t* size);
bool hw_nvs_erase_key(const char* namespace, const char* key);
bool hw_nvs_get_stats(nvs_stats_t* stats);
```

**GPIO Map Management:**
```c
typedef struct {
    gpio_pin_config_t pins[GPIO_NUM_MAX]; // All GPIO pin configurations
    uint32_t used_pin_count;              // Number of used pins
    uint32_t conflict_count;              // Number of detected conflicts
    bool map_validated;                   // GPIO map validation status
} gpio_map_t;

// GPIO map management API
bool hw_gpio_initialize_map(void);
bool hw_gpio_reserve_pin(uint8_t gpio_num, gpio_function_t function, 
                        const char* component_name);
bool hw_gpio_release_pin(uint8_t gpio_num);
bool hw_gpio_validate_map(void);
bool hw_gpio_detect_conflicts(gpio_conflict_t* conflicts, size_t* count);
bool hw_gpio_get_map(gpio_map_t* map);
```

**Hardware Resource Conflict Detection:**
```c
typedef enum {
    HW_CONFLICT_GPIO_DUPLICATE = 0,  // Same GPIO used by multiple components
    HW_CONFLICT_I2C_ADDRESS = 1,     // I2C address conflict
    HW_CONFLICT_SPI_CS = 2,          // SPI chip select conflict
    HW_CONFLICT_ADC_WIFI = 3,        // ADC2 used with Wi-Fi active
    HW_CONFLICT_STRAPPING_PIN = 4,   // Strapping pin used for I/O
    HW_CONFLICT_POWER_DOMAIN = 5     // Power domain conflict
} hw_conflict_type_t;

typedef struct {
    hw_conflict_type_t type;         // Conflict type
    uint8_t resource_id;             // Conflicting resource ID
    char component1[32];             // First component involved
    char component2[32];             // Second component involved
    char description[128];           // Human-readable description
} hw_conflict_t;
```

## 3. Requirements Coverage

### 3.1 System Requirements (SR-XXX)

| Feature | System Requirements | Description |
|---------|-------------------|-------------|
| **F-HW-001** | SR-HW-001, SR-HW-002, SR-HW-003, SR-HW-004 | Sensor abstraction layer and state management |
| **F-HW-002** | SR-HW-005, SR-HW-006, SR-HW-007, SR-HW-008 | Hardware interface abstraction and GPIO discipline |

### 3.2 Software Requirements (SWR-XXX)

| Feature | Software Requirements | Implementation Details |
|---------|---------------------|----------------------|
| **F-HW-001** | SWR-HW-001, SWR-HW-002, SWR-HW-003 | SAL interface, sensor drivers, state machine |
| **F-HW-002** | SWR-HW-004, SWR-HW-005, SWR-HW-006 | Interface abstraction, GPIO management, conflict detection |

## 4. Component Implementation Mapping

### 4.1 Primary Components

| Component | Responsibility | Location |
|-----------|---------------|----------|
| **Sensor Abstraction Layer** | Uniform sensor interface, state management | `drivers/sensor_abstraction/` |
| **Hardware Interface Manager** | Interface abstraction, resource management | `drivers/hw_interface_mgr/` |
| **GPIO Manager** | GPIO discipline, conflict detection | `drivers/gpio_manager/` |
| **Sensor Drivers** | Hardware-specific sensor implementations | `drivers/sensors/` |

### 4.2 Supporting Components

| Component | Support Role | Interface |
|-----------|-------------|-----------|
| **ESP-IDF Wrappers** | Low-level hardware access | `ESP_IDF_FW_wrappers/` |
| **Diagnostics** | Hardware fault reporting | `application_layer/diag_task/` |
| **Machine Constant Manager** | Hardware configuration management | `application_layer/business_stack/machine_constant_manager/` |

### 4.3 Component Interaction Diagram

```mermaid
graph TB
    subgraph "Hardware Abstraction Feature"
        SAL[Sensor Abstraction Layer]
        HW_MGR[Hardware Interface Manager]
        GPIO_MGR[GPIO Manager]
        SENSOR_DRV[Sensor Drivers]
    end
    
    subgraph "Application Layer"
        SENSOR_MGR[Sensor Manager]
        PERSIST[Persistence]
        DIAG[Diagnostics]
    end
    
    subgraph "ESP-IDF Wrappers"
        I2C_WRAP[I2C Wrapper]
        SPI_WRAP[SPI Wrapper]
        UART_WRAP[UART Wrapper]
        ADC_WRAP[ADC Wrapper]
        GPIO_WRAP[GPIO Wrapper]
    end
    
    subgraph "Physical Hardware"
        SENSORS[Physical Sensors]
        SD_CARD[SD Card]
        OLED[OLED Display]
        BUTTONS[Buttons]
    end
    
    SENSOR_MGR --> SAL
    SAL --> SENSOR_DRV
    SENSOR_DRV --> HW_MGR
    
    HW_MGR --> I2C_WRAP
    HW_MGR --> SPI_WRAP
    HW_MGR --> UART_WRAP
    HW_MGR --> ADC_WRAP
    
    GPIO_MGR --> GPIO_WRAP
    
    I2C_WRAP --> SENSORS
    SPI_WRAP --> SD_CARD
    UART_WRAP --> SENSORS
    ADC_WRAP --> SENSORS
    GPIO_WRAP --> BUTTONS
    GPIO_WRAP --> OLED
    
    SAL -.->|Hardware Events| DIAG
    HW_MGR -.->|Resource Conflicts| DIAG
```

### 4.4 Sensor Abstraction Flow

```mermaid
sequenceDiagram
    participant APP as Application
    participant SAL as Sensor Abstraction Layer
    participant DRV as Sensor Driver
    participant HW as Hardware Interface
    participant SENSOR as Physical Sensor
    
    Note over APP,SENSOR: Sensor Access Through Abstraction
    
    APP->>SAL: sal_readSensor(sensor_id)
    SAL->>SAL: validateSensorState(sensor_id)
    
    alt Sensor State Valid
        SAL->>DRV: driver_read_raw(sensor_id)
        DRV->>HW: hw_i2c_read(port, addr, data)
        HW->>SENSOR: I2C transaction
        SENSOR-->>HW: sensor_data
        HW-->>DRV: raw_value
        DRV->>DRV: convert_value(raw_value)
        DRV-->>SAL: converted_value
        SAL->>SAL: validateReading(converted_value)
        SAL-->>APP: sensor_reading
    else Sensor State Invalid
        SAL->>SAL: attemptSensorRecovery(sensor_id)
        SAL-->>APP: error_sensor_not_ready
    end
```

## 5. Feature Behavior

### 5.1 Normal Operation Flow

1. **System Initialization:**
   - Initialize GPIO map and validate pin assignments
   - Detect hardware resource conflicts and report violations
   - Initialize hardware interface abstractions (I2C, SPI, UART, ADC)
   - Scan for connected sensors and initialize sensor drivers
   - Establish sensor abstraction layer and state management

2. **Sensor Management:**
   - Maintain sensor state machine for all detected sensors
   - Provide uniform access interface regardless of hardware interface
   - Handle sensor failures and recovery attempts
   - Monitor sensor health and performance metrics

3. **Hardware Interface Management:**
   - Enforce GPIO discipline and prevent strapping pin usage
   - Manage shared resources and prevent conflicts
   - Provide consistent interface abstraction across all hardware types
   - Monitor interface health and detect hardware failures

4. **Resource Conflict Prevention:**
   - Validate GPIO assignments during initialization
   - Detect and report hardware resource conflicts
   - Enforce ADC1/ADC2 separation when Wi-Fi is active
   - Maintain canonical GPIO map as single source of truth

### 5.2 Error Handling

| Error Condition | Detection Method | Response Action |
|----------------|------------------|-----------------|
| **GPIO Conflict** | Pin assignment validation | Report conflict, prevent initialization |
| **Sensor Communication Failure** | Interface timeout/error | Mark sensor as faulty, attempt recovery |
| **Hardware Interface Failure** | Transaction failure | Report hardware fault, disable interface |
| **Strapping Pin Usage** | GPIO map validation | Prevent usage, report configuration error |
| **ADC2/Wi-Fi Conflict** | Resource validation | Force ADC1 usage, report conflict |
| **I2C Address Conflict** | Device scanning | Report conflict, disable conflicting devices |

### 5.3 State-Dependent Behavior

| System State | Feature Behavior |
|-------------|------------------|
| **INIT** | Initialize hardware abstractions, detect sensors |
| **RUNNING** | Full hardware abstraction, continuous sensor monitoring |
| **WARNING** | Enhanced hardware monitoring, sensor health checks |
| **FAULT** | Critical hardware functions only, preserve sensor states |
| **OTA_UPDATE** | Maintain hardware state, suspend sensor operations |
| **TEARDOWN** | Graceful hardware shutdown, preserve configurations |
| **SERVICE** | Limited hardware access for diagnostics |
| **SD_DEGRADED** | Continue sensor operations, report storage degradation |

## 6. Feature Constraints

### 6.1 Timing Constraints

- **Sensor State Transitions:** Maximum 100ms for state changes
- **Hardware Interface Operations:** Bounded timeouts for all transactions
- **GPIO Conflict Detection:** Complete during system initialization
- **Sensor Recovery Attempts:** Maximum 3 attempts with exponential backoff

### 6.2 Resource Constraints

- **GPIO Usage:** Enforce strapping pin restrictions and conflict prevention
- **I2C Pull-ups:** Physical pull-ups required (2.2kΩ - 4.7kΩ for 3.3V)
- **ADC Constraints:** ADC1 only when Wi-Fi active, ADC2 when Wi-Fi inactive
- **Memory Usage:** Maximum 32KB for abstraction layer buffers and state

### 6.3 Hardware Constraints

- **ESP32-S3 Limitations:** Respect hardware capabilities and restrictions
- **Interface Speeds:** I2C up to 400kHz, SPI up to 80MHz
- **Voltage Levels:** 3.3V logic levels for all interfaces
- **Current Limitations:** Respect GPIO current drive capabilities

## 7. Interface Specifications

### 7.1 Sensor Abstraction Layer API

```c
// SAL initialization and management
bool sal_initialize(void);
bool sal_detectSensors(void);
bool sal_getSensorCount(uint8_t* count);
bool sal_getSensorList(uint8_t* sensor_ids, size_t* count);

// Sensor operations
bool sal_readSensor(uint8_t sensor_id, float* value);
bool sal_readMultipleSensors(uint8_t* sensor_ids, size_t count, 
                            sensor_reading_t* readings);
bool sal_calibrateSensor(uint8_t sensor_id, const calibration_data_t* cal_data);
bool sal_resetSensor(uint8_t sensor_id);

// Sensor state and health
sensor_state_t sal_getSensorState(uint8_t sensor_id);
bool sal_getSensorHealth(uint8_t sensor_id, sensor_health_t* health);
bool sal_performSensorDiagnostics(uint8_t sensor_id, sensor_diagnostics_t* diag);
```

### 7.2 Hardware Interface Manager API

```c
// Interface initialization
bool hwMgr_initialize(void);
bool hwMgr_initializeI2C(uint8_t port, const i2c_config_t* config);
bool hwMgr_initializeSPI(uint8_t host, const spi_config_t* config);
bool hwMgr_initializeUART(uint8_t port, const uart_config_t* config);
bool hwMgr_initializeADC(const adc_config_t* config);

// Resource management
bool hwMgr_reserveResource(hw_resource_type_t type, uint8_t resource_id, 
                          const char* component_name);
bool hwMgr_releaseResource(hw_resource_type_t type, uint8_t resource_id);
bool hwMgr_validateResources(void);
bool hwMgr_getResourceConflicts(hw_conflict_t* conflicts, size_t* count);
```

### 7.3 GPIO Manager API

```c
// GPIO management
bool gpioMgr_initialize(void);
bool gpioMgr_reservePin(uint8_t gpio_num, gpio_function_t function, 
                       const char* component_name);
bool gpioMgr_releasePin(uint8_t gpio_num);
bool gpioMgr_configurePin(uint8_t gpio_num, const gpio_config_t* config);

// GPIO validation and conflict detection
bool gpioMgr_validateGPIOMap(void);
bool gpioMgr_isStrappingPin(uint8_t gpio_num);
bool gpioMgr_detectConflicts(gpio_conflict_t* conflicts, size_t* count);
bool gpioMgr_getGPIOMap(gpio_map_t* map);
```

## 8. Testing and Validation

### 8.1 Unit Testing

- **Sensor Abstraction:** All sensor types and state transitions
- **Interface Abstraction:** I2C, SPI, UART, ADC operations
- **GPIO Management:** Pin assignment and conflict detection
- **Resource Management:** Resource allocation and validation

### 8.2 Integration Testing

- **Cross-Interface Testing:** Multiple interfaces operating simultaneously
- **Sensor Integration:** All sensor types through abstraction layer
- **Resource Conflict Testing:** Deliberate conflict scenarios
- **State Coordination:** Hardware abstraction with system states

### 8.3 System Testing

- **Hardware Compatibility:** All supported sensor hardware configurations
- **Performance Testing:** Interface throughput and timing constraints
- **Fault Injection:** Hardware failure simulation and recovery
- **Long-Duration Testing:** Extended operation with hardware monitoring

### 8.4 Acceptance Criteria

- All sensor types accessible through uniform SAL interface
- Hardware interfaces properly abstracted from application layer
- GPIO conflicts detected and prevented during initialization
- No direct hardware access from application components
- Sensor state management operates correctly under all conditions
- Hardware resource conflicts properly detected and reported
- Complete hardware abstraction maintains system performance

## 9. Dependencies

### 9.1 Internal Dependencies

- **Sensor Manager:** Primary consumer of sensor abstraction layer
- **Diagnostics:** Hardware fault reporting and event logging
- **Machine Constant Manager:** Hardware configuration management
- **State Manager:** Hardware behavior coordination across system states

### 9.2 External Dependencies

- **ESP-IDF Framework:** Low-level hardware drivers and HAL
- **Hardware Components:** Physical sensors, interfaces, and peripherals
- **FreeRTOS:** Task coordination and resource management
- **Hardware Design:** GPIO assignments and interface configurations

## 10. Future Enhancements

### 10.1 Planned Improvements

- **Dynamic Sensor Discovery:** Runtime sensor detection and configuration
- **Advanced Sensor Fusion:** Multi-sensor data correlation and validation
- **Hardware Health Monitoring:** Predictive hardware failure detection
- **Plug-and-Play Support:** Hot-swappable sensor support

### 10.2 Scalability Considerations

- **Additional Sensor Types:** Framework supports easy sensor type extension
- **Multiple Interface Support:** Support for additional hardware interfaces
- **Advanced GPIO Management:** Dynamic GPIO allocation and optimization
- **Hardware Virtualization:** Virtual hardware interfaces for testing

---

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