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Circuit Description

This simple circuit demonstrates the flipflop components included in the Hades hades.models.flipflops package.

Each flipflop output is simply connected to a LED (Opin), and each input is connected to switches. The default values for all switches are U in order to also demonstrate the flipflop reset or initialization.

Just play with all the circuits to gain an understanding of the differences between latches (level-sensitive) and edge-triggered flipflops. What happens when you change the D input value while the clock input value is high? Which of the inputs to the DFFRS flipflop with D, SET, and RESET inputs has precedence?

Note that the applet also includes two metastable flipflops. These flipflops behave like the normal flipflops when all inputs are well-defined. When encountering input timing violations or undefined input values, however, these simulation models do not generate X or U output values but enter random 0 or 1 states after (possibly long) random delays. Use shift-click on the input pins to generate Z and U input values for these flipflops and then click the other inputs to view this random behavior. Warning: The metastable flipflop models are meant for demonstration purposes only, and should never be used for 'real' designs. For further details, please also read the comments for the metastable JK flipflop applet.