Lesson Notes By Weeks and Term v4 - SHS 3
Digital and Analogue System Design
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Digital and Analogue System Design
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Subject: Robotics
Class: SHS 3
Term: 2nd Term
Week: 20
Grade code: 3.2.1.LI.2
Strand code: 2
Sub-strand code: 1
Content standard code: 3.2.1.CS.1
Indicator code: 3.2.1.LI.2
Theme: Robot Design Methodologies
Subtheme: Digital and Analogue System Design
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In our daily lives in Ghana, we interact with many automated systems. Think about the traffic lights at the Kaneshie market, an automatic gate at a modern house, or even the system that stops a microwave when you open the door. These systems are not magic; they are built on the principles of digital logic. They take in information (inputs), make a decision based on set rules, and then perform an action (output). This lesson will equip you with the fundamental skills to be a creator, not just a user, of these systems. We will learn a structured, step-by-step process to move from a real-world problem—like managing the water in a "Polytank"—to a complete, efficient digital circuit design.
This entire process is called Combinational Logic Design. A combinational circuit is one where the output at any time depends *only* on the combination of inputs at that same time. It has no memory of past inputs.
We will use a practical Ghanaian example to walk through the complete design process: Designing an automatic pump controller for a "Polytank" water tank. The Design Process: A Step-by-Step Guide
Scenario: We need to design a system that automatically controls the water pump for a Polytank. The system should turn the pump ON when the water is low and turn it OFF when the tank is full to prevent overflow and save electricity.
Step 1: Analyse the Scenario and Define Requirements Goal: Control a water pump (P). Condition for ON: The pump should be running if the water level is not yet full. Condition for OFF: The pump should stop when the water level reaches the 'full' mark. Sensors: We need sensors to detect the water level. Let's use two: a "Low Sensor" (L) near the bottom and a "High Sensor" (H) near the top.