Well, here is what you've all been waiting for! This is the block diagram of our system. Each of the blocks represents a sub-system that was designed in other parts of this website.

For convenience and clarity, the pin numbers have been left off the PLD. If one wants to know what they are, you can easily view the Controller.rpt file and find them out. I did not show the state output of the PLD because we are only interested in the final output (Z1 and Z2). Also, for a real PLD, there would be several unused inputs. In order to protect the PLD from static damage, these unused inputs would have to be tied low or high. For convenience, I put only one ground; I am assuming all unused inputs are tied to it.

The PLD has nine important input/outputs. These pins are: clock, power (5V), ground, reset, inputs X1, X2, and X3 and outputs Z1 and Z2. Reset is not shown in the diagram. Incidentally, we most likely would not need a reset pin; the PLD is supposed to reset automatically when it is powered up. The remaining pins are unused. The PLD itself is a GAL16v8B from Lattice Semi-conductor. Like virtually all PLD's in the market today, it uses CMOS technology.

The clock block derives from the clock diagram located in the clock website portion of our project website.

The input interface circuitry block comes directly from the interface diagram in the interface website portion of our project website. The pull-up resistors are located within the block. The power supply wire pointing towards the input sensors represents the supply voltage used by the switches to indicate what kind of input has been detected.

The output interface circuitry derives from both diagrams in the output interface website portion of the project website. For convenience, I put both circuits within one block. The two common wires for each terminal of the motor represent the two possible paths current can flow through the motor, clockwise or counter-clockwise. These two directions dictate the direction of the motor movement. Because current can flow in two directions through the motor terminals (or none at all), I didn't put any arrows on the ends of the two wires.

As you can see, power is provided to all blocks except the input interface block. The input interface block does not need power entering the block because its power derives from the switches on the robot claw.