I heard about this fun contest called the 7400 contest. The goal of this competition was to build something out of 7400 series discrete logic chips. This sounded like an exciting and interesting contest, so I set to work thinking of ideas.
After some brainstorming, my girlfriend Kayla and I decided that making a PONG game on an LED matrix would be pretty neat. We figured out the general overlay of what we needed to do and started off by ordering some cheap LED matrices from futurlec.com, along with some buttons for input, and a few other random things for other various projects.
Next we got to work designing the actual logic for the game. I decided to break down the game mechanics into 4 states. State 0 is the main playing state. In this state, the logic checks for things like ball collision with the paddle, the ball being past the paddle, changing the direction of the ball, and updating the coordinates of the ball. If the ball makes it past the paddle, the score is adjusted and the state is changed. If the score reaches 8 points, the state is changed to state 3, otherwise the state is changed to state 1. State 1 is just for getting the various registers set up for the next round. This includes setting the coordinates and direction of the ball, putting the ball on the side of whoever was scored on last. It then moves into state 2. State 2 simply waits for input on the GO button. This input is latched in. When input is received, the state is changed back to state 0, and play resumes. If someone reaches 8 points, state 3 is entered. This state disables the ball and paddle drawing logic, and instead draws a message to the screen, either “P1 WIN” or “P2 WIN”, depending on who won. It also waits for input on the GO button before clearing the scores and changing to state 1.
After we figured out what all chips we wanted, we sent in orders to Mouser and Jameco.
At this point, it had been a month since the initial futurlec order, and I had just noticed that it still hadn’t shipped. I contacted them and they said that they hadn’t shipped it because one of the parts that I had ordered was out of stock. I had them cancel that part from my order and send the rest of the items.
The Mouser and Jameco orders arrived on time, and we began trying some things out on the breadboard, as well as figuring out where we would put stuff on the prototyping solder boards. However, with only two days left, and still no futurlec order, we were missing crucial components, such as more solder board, buttons, and displays.
Unfortunately the delayed order, as well as a few other difficulties we encountered, caused us to have to give up on getting this done in time for the competition. However, when we get in our order, and have some extra time to spare, we plan on finishing this project.
In this post, I’ve included a pdf of the schematic we had going. It doesn’t have everything in it, as I didn’t think some things were worth bothering to put into the simulation. Also, I’ve included a picture of some of my hand-drawn schematics and notes spread out on the floor.
Schematics and notes, strewn across the floor.