A Really Solderless Breadboard — Part 1
R1, R2 - 10K resistor, 1/4 watt
R3, R4 - 470 W resistor, 1/4 watt
S1, S2 - SPST switch
LED1, LED2 — Standard light emitting diode or 5 V LED (if using 5 V
LED, omit R3 and R4 and simply connect the LED to ground).
PBX- 84 circuit board (available from the author)
As a special service, the author has a limited number of special
Nuts & Volts kits available. Each kit contains a PBX- 84 kit, a JTAG programmer kit, an XC9572 IC, and all the parts listed above. Visit
www.al-williams.com/nvkit.htm for details and to place an order.
into the inputs.
At this point, all you've done is define the
inputs; the outputs are not correct. You can set
the end of the test bench by right clicking on the
display at the time you want to set as the end point
and select Set End of Testbench from the menu. A
vertical blue line shows the end of the test. When
you save the test bench, the program may ask you
if you want to extend the end of the test.
The easiest way to see the results of the
simulation is to return to the Project Navigator
and select Generate Expected Simulation Results. This will
produce the waveform seen in Figure 7. This waveform
confirms that the adder works as expected.
Figure 7. Test bench results.
Since this circuit is so simple, you can depend on the
final result working. All you need to do is fit the design into
your CPLD. If you are using the PBX84 prototype board, it
is handy to put the inputs and outputs on the strip of I/O
pins that connect directly to the breadboard. To do this,
you'll need to set constraints.
The easiest way to set these constraints is to use the
User Constraints selection of Project Navigator (under
Affordable Motion Control Products
NUTS & VOLTS
Circle #143 on the Reader Service Card.