Using Xilinx Foundation Series Software: Observation of Functional Simulation within the Schematic Editor

Using Xilinx Foundation Series Software:

Observation of Functional Simulation within the Schematic Editor

To observe the simulation in the Schematic Editor window, the circuit has to have been set up for Waveform Viewer simulation, this includes adding signals, stimulus, and clock frequency steps in the Sim Funct window. See: Using Xilinx Foundation Series Software: Functional Simulation in the Waveform Viewer
In the Win95 taskbar or the Xilinx Program Manager, open the Schematic Editor. The Schematic Editor window should appear with colored boxes (probes) representing the value (0 or 1) at that point in the circuit.
To control the simulation from the Schematic Editor window you will need the Simulation Toolbox, its button is on the top toolbar. Click on it and the SC Probes toolbox will appear.

The buttons in the SC Probes toolbox are very useful during simulation. Their uses are explained below.

	- Probe tool, displays logic value at that point in the circuit during simulation.
	- Stimulator tool adds stimulus at that point in the circuit during simulation.
	- Simulator, switches simulation window to the Waveform Viewer.
	- Delete Probes, deletes all probes from design. (Be Careful)
	-Previous Event, steps simulation back to the previous logic value change.
	- Next Event, steps simulation forward to the next logic value change.
	- Simulate, increments the simulation forward by one long step.
	- Save Probes, saves probes configuration for later use.

It is useful to add probes to the circuit to understand the way the signals propagate through the gates and buffers. To add probes, select the Probe Tool in the SC Probes toolbox, and place them in the circuit by clicking on various points in the circuit.
Step the simulation forward a couple of times to observe the propagation of the values through the logic circuit. Note: This can be extremely helpful when debugging a circuit that doesn't work correctly. The probes make it obvious where the logic is wrong, or the wires are not correctly connected.