Variables and Physical Construction
Our input variables consisted of an Open Switch button, a Closed Switch button, an Open Limit Switch, and a Closed Limit Switch. These were real world inputs, four switches which gave information to the PLD and motor controller chips. Open and Closed Limit Switch were attached to the VEX build and told whether or not the gate was finished opening or finished closing. The Closed and Open buttons were used to make the gate open or close once it was at rest in either a fully opened or closed state.
Our output variables were Motor Open/Close and Gate Open/Close. These outputs controlled the movement of the gate as well as indicating on the chip what state the gate was in. Motor Open/Close controlled when and what direction the motor would run. Gate Open/Close were wired to two LEDs which were lit depending on whether the booth was fully closed or fully open.
Basically, the simulation should create a four part action that the gate goes through. First, when at rest in the first state, the gate (the metal bar) is closed and touching the limit switch that tells the PLD that the gate is closed. Then, when you hit the Open button, the gate begins to lift. Third, the gate stops opening up once the metal bar hits the Open Limit switch and it is in an open state, which the PLD chip now knows. Lastly, the Close button is pressed and the gate begins lowering back down until reaching state 1 again.
Our output variables were Motor Open/Close and Gate Open/Close. These outputs controlled the movement of the gate as well as indicating on the chip what state the gate was in. Motor Open/Close controlled when and what direction the motor would run. Gate Open/Close were wired to two LEDs which were lit depending on whether the booth was fully closed or fully open.
Basically, the simulation should create a four part action that the gate goes through. First, when at rest in the first state, the gate (the metal bar) is closed and touching the limit switch that tells the PLD that the gate is closed. Then, when you hit the Open button, the gate begins to lift. Third, the gate stops opening up once the metal bar hits the Open Limit switch and it is in an open state, which the PLD chip now knows. Lastly, the Close button is pressed and the gate begins lowering back down until reaching state 1 again.
Multisim PLD Construction
VEX Construction
Conclusion
In the beginning the looked over the project requirements and the packet so we could get an idea of what we were doing. Then, as instructed by the packet, we copied down the State Diagram as well as the State Truth Table from the PLTW website and interpreted the real world meaning behind each state change so we could have a better idea of how to build the circuit as well as visualizing what sort of motions the VEX structure would go through, this included making simplified expressions from the State Truth Table. Next, my partner Matthew began building the circuit in Multisim while I built the VEX prototype. I finished the structure with ease, eyeballing most of it, and Matt continued building and debugging his circuit while I went on to begin bread boarding in preparation for the PLD upload Matt would put onto the board. Eventually Matt finishes the circuit and I nearly finish the bread boarding by this time. Despite needing to be reminded that the LED outputs were not wired, the prototype functioned with astounding success on its first try.
The biggest difference between this project and previous ones is that this is the first time our circuit building, bread boarding, and mechanical engineering skills have come together, something I enjoyed very much since up until now the extent of our circuity and bread boarding has just been LEDs and numbers on a screen. Unfortunately I scrolled past the schematics for bread boarding at first, making the process more difficult than it needed to be, but I did understand them once I started using them at the very end, and it was easier than at the beginning of the year. Lastly, if I did this project again then I would have the same partner, whether it be me or someone else, do both the bread boarding and the circuit building since for half of a class I had a hard time wrapping my head around where the inputs and outputs went, and what they were supposed to connect to or be used for, like handing someone art and expecting you to know how to perfectly replicate it, and then some.
In the end, I enjoyed this project a lot.
The biggest difference between this project and previous ones is that this is the first time our circuit building, bread boarding, and mechanical engineering skills have come together, something I enjoyed very much since up until now the extent of our circuity and bread boarding has just been LEDs and numbers on a screen. Unfortunately I scrolled past the schematics for bread boarding at first, making the process more difficult than it needed to be, but I did understand them once I started using them at the very end, and it was easier than at the beginning of the year. Lastly, if I did this project again then I would have the same partner, whether it be me or someone else, do both the bread boarding and the circuit building since for half of a class I had a hard time wrapping my head around where the inputs and outputs went, and what they were supposed to connect to or be used for, like handing someone art and expecting you to know how to perfectly replicate it, and then some.
In the end, I enjoyed this project a lot.