SmartSwitch Logic — Combinational Device Controller

Overview

A smart-home device selector controlling multiple appliances via an 8-key keypad in manual and automatic modes, built under a strict architectural constraint: combinational logic only, no sequential elements. That constraint forced genuinely careful priority-resolution design for simultaneous key presses.

Architecture

Encoder/decoder and multiplexer-based combinational logic resolving keypad input into appliance control signals, with hardcoded safety interlocks between conflicting device categories.

Key Features

• Priority resolution logic for simultaneous key presses.
• Manual and automatic (preset) operation modes.
• Safety-critical interlocks — e.g. AC automatically disabled while the heater is active.
• Full validation across manual, automatic and edge-case input scenarios.

Development Process

• Enumerated every possible simultaneous key-press combination before designing priority logic.
• Built encoder/decoder/MUX logic to resolve keypad state into appliance signals combinationally.
• Hardcoded safety interlocks as explicit logic constraints, not runtime checks.
• Simulated and validated manual, automatic and edge-case behavior in Proteus/Tinkercad.

Challenges & Solutions

Results & Impact

The system correctly resolves conflicting inputs, enforces safety interlocks, and switches cleanly between manual and automatic modes — entirely without sequential logic.

Future Improvements

• Extend to more appliance categories.
• Add a physical keypad prototype.
• Introduce configurable interlock rules.