# HMI Controller Component
## ASF Sensor Hub (Sub-Hub) Embedded System

**Component ID:** C-HMI-001  
**Version:** 1.0  
**Date:** 2025-02-01  
**Location:** `application_layer/business_stack/hmi_controller/`  
**Display:** OLED 128x64 (I2C)

---

## 1. Component Overview

The HMI Controller provides local human-machine interface functionality including OLED display management, button input handling, and menu navigation. This component enables local status monitoring and basic diagnostics access.

**Primary Purpose:** Provide local user interface for system status and diagnostics.

---

## 2. Responsibilities

### 2.1 In-Scope

- OLED display initialization and management
- Display content rendering
- Button input handling (Up, Down, Select)
- Menu system implementation
- Status information display
- Diagnostic information display
- Sensor information display

### 2.2 Out-of-Scope

- Configuration changes (read-only interface)
- System control (handled by System State Manager)
- Data modification (handled by authenticated sessions)

---

## 3. Provided Interfaces

### 3.1 Display Interface

```c
/**
 * @brief Initialize HMI Controller
 * @return true on success
 */
bool hmi_init(void);

/**
 * @brief Update display with system status
 * @param status System status structure
 * @return true on success
 */
bool hmi_update_status(const system_status_t* status);

/**
 * @brief Display diagnostic information
 * @param diag_info Diagnostic information structure
 * @return true on success
 */
bool hmi_display_diagnostics(const diagnostic_info_t* diag_info);
```

### 3.2 Button Interface

```c
/**
 * @brief Get button input
 * @param button_state Output button state
 * @return true if button pressed
 */
bool hmi_get_button_input(button_state_t* button_state);
```

---

## 4. Display Content

### 4.1 Main Screen

- Connectivity status
- System state
- Connected sensor count
- Current time/date
- Error indicator

### 4.2 Menu Structure

```
Main Menu
├── Status
│   ├── System State
│   ├── Sensors
│   └── Connectivity
├── Diagnostics
│   ├── Recent Events
│   ├── Error Count
│   └── System Health
└── About
    ├── Firmware Version
    └── Device ID
```

---

## 5. Dependencies

- **OSAL-I2C:** OLED display communication
- **OSAL-GPIO:** Button input
- **System State Manager:** System state information
- **Diagnostics Manager:** Diagnostic information
- **Time Utils:** Time/date display

---

## 6. Traceability

### 6.1 System Requirements

- **SR-SYS-007:** OLED display interface
- **SR-SYS-008:** System information display
- **SR-SYS-009:** Button navigation
- **SR-SYS-010:** Diagnostic menu access

---

**Document Status:** Complete  
**Next Review:** Before implementation