||University of California at Berkeley
||College of Engineering
||Department of Electrical Engineering and Computer Sciences
|CS 150, Fall1997
||J. Wawrzynek, N. Weaver
|September 12, 1997
||Modified by R. Fearing, and D. Young
Finite State Machine on Xilinx
Put your combination lock from Lab 2 onto a chip. To do this, you will:
Figure 1. Steps taken in this lab to compile, download, and
Use Xilinx Design Manager to compile and route your design.
Use Xilinx Hardware Debugger to do real-time hardware debugging and watch
For a design to be useful, it must make its way into hardware. To do
this we will be using Xilinx Field Programmable Gate Arrays (FPGAs), chips
that can be configured as many different circuits. Specifically, we will
be using the Xilinx XC4000 Design Demonstration Board, which contains an
XC4005E FPGA, switches, and light-emitting diodes.
These boards are very expensive and not easily replaced. Be very
careful with these. Make sure that they stay on the anti-static mat. Make
sure also that the ground plug is plugged in. Before touching the Xilinx
board, ground yourself-- touch any metal you can find or the static mat.
Do not take the Xilinx boards or anything else from 204B Cory!
2.1 Xilinx Interface
Answer the questions on the checkoff sheet.
Make sure your Lab 2 design works and the labels in your schematic match
the labels shown in the example.
Also check that none of your filenames are long than 8 characters. We're
using new software so this might or might not be a problem (it's better
to be safe though).
Make sure your schematic does not use any components from the builtin
library. If you followed the instructions in Lab 2, this should not be
Make sure none of your symbols or components have the same name as components
in the (xc4005e) library, such as DFF or CLB.
If you did, rename your components.
To compile your design for the Xilinx, some interface components need
to be added. We have done the busy work for you. (See section 3.1 below)
2.1.1 I/O Pads
I/O pads and buffers are special cells in the (xc4005e) library,
connect the Xilinx to the outside world of buttons, LEDs, and other chips:
Each IPAD and OPAD is connected to a particular pin on
the Xilinx, designated by the LOC attribute. For example, in our
schematic, the IPAD in the upper-left corner, SW5-1,
has the attribute LOC=P27, indicating it connects to pin 27 of
Your lock expects ENTER and RESET to be high for exactly
one clock cycle every time it is pressed. The DEBOUNCE circuit,
a simple state machine, ensures this.
3 Add the Xilinx Interface Circuits
We have entered the required interface circuits; you need to copy them
into your design. You need to open the TA-provided design and save it as
the second sheet in your combination lock schematic.
Like on one-sheet schematics, nets with the same label on different
sheets of the same schematic are connected implicitly.
4 Export your design to an EDIF file
Start ViewDraw. Open the lab3.1 in the (cs150) library.
Choose File -> Save Copy As. Enter FSM.2 [Note: If you
named the top level of your lab 2 combination lock something other than
FSM, you'll need to substitute your filename for FSM]
Open FSM.2 in Viewdraw. Do File -> Save and Check. Examine
the design demonstration board schematic in your reader and note how the
XC4005[A] is connected to the LEDs, DIP switches, etc.
In order to compile your schematic, you first need to export your schematic
into an EDIF file. Note that the EDIF file is created from the wire file
that is updated when you do Save and Check from inside ViewDraw.
So, it's very important to use Save and Check.
These steps will create a file with the .EDN extension.
Load your top-level schematic (for example, FSM.1)
Choose Tools -> Export EDIF (common)
Click on the EDIF Net List Writer tab near the top of the window
Set Input to the name of the wire file for the schematic
you're working on (in our example, projdir\wir\FSM.1).
The output field should be filled in automatically.
In the Level field near the middle of the window, enter xilinx.
Click on the Apply button at the bottom of the window. Note any
errors and hit Cancel to close the window.
5 Run Xilinx Design Manager to Compile Your Schematic
Xilinx Design Manager will compile and route the EDIF netlist
into a bit file that can be downloaded to the Xilinx chip. Xilinx Design
Manager maintains a project file like Workview Office's Project Manager.
However, the two are different and unrelated. The first thing you'll
need to do is set up a Xilinx Design Manager project file.
5.1 Making a Xilinx Design Manager project file
5.2 Compile Your Design
Start Xilinx Design Manager. It is a program in the Xilinx directory.
There should be a shortcut to it on the desktop.
Choose File->New Project from the menu bar.
Enter the name of the EDIF file you created (or click the Browse
button and find the file).
Save the project file by choosing File->Save.
Once you have created a project file, you can generate the .BIT
file. .BIT files are different depending on the chip that you're
compiling for, so the correct settings have to be entered. This semester
we're using the XC4005E-PC84-4
6 Download and Test the Circuit
Choose Design->Implement from the menu bar in Xilinx Design Manager.
Set the following parameters:
Click the Run button. A new window will pop up showing the progress
of the compilation and routing. During this process a bunch of output files
with very detailed information are created. If there are errors, view the
log file. Even if the compilation is successful, you can read the log file
to find out some details of the compilation and routing.
There is a tool that let you see graphically the resulting mapping of the
logic in the Xilinx chip. Ask your TA how to use it if you're interested
(it's pretty neat to see).
Xilinx's Hardware Debugger is a real-time hardware debugging
tool. With it, you can step through clock cycles and observe the actual
values of internal nodes! (This is new. We didn't have this capability
in previous semesters.) If you check the TA provided schematics, you'll
notice that it includes a "readback" block. This is used to recover the
values of internal nodes. It is a component in the CS150 directory.
6.1 Connect the power cables and XChecker cables
The power supplies have a cable with two banana plugs, red and black,
and a yellow lead. The black is ground, the red is +5V, and the yellow
is -5V. Don't attach the -5V connector to anything, and make sure it
doesn't touch anything metal!
You'll also need to plug in the XChecker cable. It has a rectangular plug
connected to a bunch of wires. It only fits in one direction. You shouldn't
have to force it. (One of the openings in the plug is filled with epoxy.
It corresponds to the area without a pin on the board.) Ask your TA if
you have any questions here.
Plug in the power supply.
Connect the black banana plug to the board.
Connect the red banana plug. The decimal point on CR3 (the left
seven-segment LED) should light, indicating the power is on.
6.2 Download the circuit
6.3 Observe the circuit in operation
Start Hardware Debugger by choosing Tool->Hardware Debugger
from the Xilinx Design Manager menu bar. If this complains about the cable
not being connected correctly, make sure the board has powered and the
XChecker cable is attached.
You can also check the cable configuration by choosing Cable->Communcations.
The XChecker cable is hooked up to COM1 and the transfer rate should be
Choose File->New->Project and enter the name of the newly created
.BIT file. (For example, FSM.BIT)
Choose Download->Download Design or double-click on the name of
the bit file in the diagram to download the design to the Xilinx board.
In this lab, a zero should appear on the CR4 (the right 7-seg
LED), indicating that the machine is in State 0.
The clock signal for the combination lock design comes from the XChecker
cable and is fed into pin 8 of the Xilinx chip (see schematic). This is
useful for debugging because the software allows us to manually control
the clock. To manipulate the clock, we'll use the Hardware Debugger
"Readback Control Panel". From the control panel, we can also watch
the internal signals and have the waveforms displayed like in ViewTrace.
6.3.1 Turn on the clock
Since the clock is coming from the XChecker cable, the lock will not
operate properly until the clock is running.
6.3.2 Test the circuit
Open the Readback Control Panel by choosing Tools->Control Panel.
On the far right, click the circle next to Start in the Clock Control
section of the control panel. You can also apply single clock pulses by
clicking the apply button while Stop is selected.
While the clock is running, test out your circuit changing the combination
and pressing the enter button.
6.3.3 View the internal variables
Test a successful combination using the buttons and switches on the design
Test an unsuccessful combination.
Make sure SW 4-7 (marked RST on the board) is closed.
Otherwise, the RESET button won't work.
Have your TA check off your working lock.
Click on the Display button and take a snapshot of the internal
Lab 3 Checkoff Sheet
Click on the Groups button. Combine state2, state1, and state0 into
a group called "state". You'll need to click the New button
to make a new group, and the Save button for the changes to take
Click on the Displays button to display waveforms for state, error,
open, and enter. A waveform window will pop up.
Go through both a successful and unsuccessful attempt at opening the lock,
taking a snapshot (click the Read button) after each state transition
(for this lab, you can leave the clock running while you do this).
To read the value of the groups, you can click with the left mouse button
on the part of the waveform you want to see. Also, pressing the plus
symbol will expand the group waveform into separate single waveforms.
Show your TA the generated waveform for checkoff.