Variables and Physical Process
For creating our Toll Booth we began the design process using a state machine. The state machine needed 4 states. They were S0, S1, S2, S3. Each state had 2 inputs, Qa and Qb. Qa and Qb represent which state the machine is in. S0 is when the gate is closed and there is a LED that signals the gate is closed. Once the open switch is hit it triggers the next state. S1 causes the motor to open up the toll booth. The motor will then keep running until it hits the open limit switch on the top of the toll booth. Once the switch is hit a LED on the board turns on showing that the gate is open triggering S2. In S2 the close switch is pressed which makes the motor run the other way closing the toll booth and leading to S3. In S3 the toll booth will close until it hits the close limit switch. The outputs are the LEDs lighting up when the gate is open or closed and the motors closing and opening the toll booth. The physical process is the arm will open when a button is pressed and stops once it reaches the top limit. When the second button is pressed the arm closes until the arm hits the lower limit switch.
Conclusion
To start off our project we first did the state graph. This mapped out all the inputs and outputs and the order the machine would operate in. The state graph had four states: S0, S1, S2, and S3. It begins as gate closed, then continues to motor open, then gate open, then motor close and finally gate closed. After that we created our transition table. The inputs and outputs from the state graph were used in the transition table. We then used the transition table to find our logic expressions. In the end you will have 6 logic expressions. After that we simplified each expression using Boolean Algebra. We had our expressions checked by Mrs. Zienty and she realized the Qa* and Qb* expressions were wrong. We checked our transition table and it seemed like they were correct based off our table. She quickly looked over our table and realized one of our inputs was wrong. Once we figured this out we fixed our expressions and they were correct. After this we built the Multisim and bradboard. While Anthony was building the Multisim, I was breadboarding. I decided to breadboard based off the picture to save time and make it easier. Once we were both done Anthony switched the pins on the Multisim to match up with the breadboard. We then hooked up the toll booth to the breadboard and were ready to test it. Our first test was not successful. There was something wrong with our Multisim so we had to wait till the next day to test it. When we got back Anthony quickly fixed the Multisim. We tested it again and it worked perfectly. We learned it was important to look over every little detail to make sure everything is working how it is supposed to be. This project was very similar to the others because of the Multisim and breadboarding. Otherwise it was different in the fact we were using Vex. I learned a lot about reading schematics. Throughout the year it became easier and easier to read and understand them. I learned to make sure the schematics on Multisim and the breadboard are the same. I believe it was a lot easier than the beginning of the year. I think this because over the year we have learned so much that now when we learn something new we can quickly understand it. One thing I would do was be in school for the lesson on state machines. This really messed me up at the start because I had no clue what we were doing.