Draw a truth table for the given scenario, including all the inputs and outputs. Write down the complete Boolean equations for each simplified output related to the inputs.
A washing machine controller has four inputs: WASH (W), TEMPERATURE (T), FULL (F), and EMPTY (E). It also has four outputs: HOT tap (H), COLD tap (C), MOTOR (M), and PUMP (P).
Inputs:
- TEMPERATURE drives high when the water in the machine is above the required temperature. Similarly, TEMPERATURE drives low when the water becomes below the required temperature.
- When the machine is completely filled with water, the FULL input should be high. While the machine is out of water, the EMPTY input should be high. When both inputs are high at the same time, all the outputs should be in a "don't care" condition.
- The WASH input should drive high when the washing cycle is ON, and the washing cycle should get OFF when the WASH input drives low.
Outputs:
- The HOT tap output should get turned ON when the washing signal is high and the water is below the temperature, while the washing machine is completely FULL with water. Similarly, the COLD tap output should get turned ON whenever the water is above the temperature.
- The Drain Pump output needs to get turned ON whenever the washing cycle is OFF, and the PUMP output should get turned OFF when the washing machine is completely out of water.
- The Motor output should get switched ON once the washing machine is FULL and when the washing cycle gets switched ON.
Note:
In the given system, the HOT and COLD taps will never be ON at the same time. If the temperature is too high, the COLD tap will be ON. If the temperature is too low, the HOT tap will be ON.
