Part 3: Logic IC Replacement

In Part 1 and Part 2, we considered the preparatory requirements. In this final part, we will consider the hardware requirements.

From the equation perspective, the code is correct. However, we need to take into consideration how the hardware interacts with the user or the actuator providing the inputs.

One of the issues with the input to PIC is the potential for false triggers. While it would be unlikely for there to be two false triggers at the same time interference on the inputs can cause them not to work or trigger properly.

A common method to negate this would be to pull the inputs high. However, that now means that your inputs are triggered. To implement this, all that would be needed is to negate the logic so that you have !A.!B = 1.

In the iteration above, when both inputs are pulled low you then have the same effect. If you noticed that the truth table is out, then you are correct. While there are other ways to implement the above, this is the most cost-effective.

Driving the output can be a simple LED resistor combination to show that the software is working. The options are there to drive more power-intensive loads.

That brings this section to a conclusion.