Testing Summary

Omnilab Setup

The equipment used for testing includes the stimulus generator, logic analyzer, and breadboard. The stimulus pins are connected to the chip inputs and to the logic analyzer pins. The chip outputs are monitored using the logic analyzer.

Test Vectors

The test vector is a concatenation of three games, allowing the low-score feature to be tested. The first game is won in two guesses. The second game is lost when the guesser exhausts the number of guesses allowed (seven). This game is designed to test the scoring capabilities of the chip by inducing a variety in the number of black and white scores. The third game is won in one guess, lowering the low-score component to one.

Functional Testing

All five chips are fully functional. The Omnilab results match the IRSIM results obtained last semester, indicating the unexpected adequacy of the simulation capabilities of IRSIM. In testing the entire chip, IRSIM indicated a few current leakage errors that were corrected before fabrication.

Omnilab Results


PINK: win-lose-keep gussing output. YELLOW: enter guess signal.

Speed Testing

Using the non-overlapping clocking scheme, the chip fails at approximately 8.5 MHz (34 MHz sampling rate). The failure location is in the output multiplexer, which displays the current guess and score. This failure does not impact the performance of other parts of the chip; the Omnilab analyzer output shows that the chip continues to go through the proper states at this frequency.


Non-Overlapping Clock


RED: errors

A possible reason for the output multiplexers failure is charge sharing. The transmission gates of the multiplexers are controlled by clka and clkabar, so the values at each of the outputs are only transmitted at selected times. Since clkabar is generated from clka through an inverter, the delay could be causing charge sharing at the connected output of the transmission gates.
Using an aggressive clocking scheme (one clock rises as the other falls), the chip similarily fails at 8.5 MHz (17 MHz sampling rate).

Aggressive Clocking


RED: errors

Possible Improvements

One improvement would be to redesign the multiplexers so that they are capable of switching at higher frequencies.
To make playing the Mastermind game more interactive, a graphical user interface could be designed for real-time play.