FIGURE 4. TI Xilinx Spartan
FPGA processor.
Over several hours of testing, I didn’t experience a
single crash.
Figure 5 shows the general flavor of the user
interface. It’s clean, colorful, and easy to navigate. At the
lower right of the screen is the main menu, where you can
select the oscilloscope or other virtual instrument. Behind
the menu is the input/output panel which I configured
from top to bottom with a seven-segment display, a
couple sliders, and binary output indicators.
In the upper left of the figure is the programmable
power supply and voltmeter. The voltmeter is virtually
hidden in the upper right corner of the panel, leaving most
of the screen real estate to the power supply. Note the
sliders for both voltage and current output.
At the lower left of the figure is the waveform
generator. I have it set for a 3. 3 Vpp, 2 kHz sine wave,
with no offset. You can see the
sliders that allow you to easily
change amplitude, frequency,
offset, and other properties.
Evaluation
There are several ways to evaluate this
hardware/software system. For example, I could focus on
the power supply and examine the ripple, noise rejection,
Using my recently calibrated
Fluke 45 DMM, a Tektronix 2022D
dual-trace digital oscilloscope, and
a B&K signal generator, I found the
virtual analog and digital input and
output devices sufficiently
accurate for the intended task.
Sure, the volt meters varied by a
few tenths of a volt here and there,
and there appeared to be a slight
falloff in response of the
oscilloscope above about 3 MHz,
but nothing significant.
To be fair, I didn’t take the
FIGURE 5. Clockwise from top left:
Virtual oscilloscope, power
supply/voltmeter, waveform
generator, and digital I/O
configuration panel.
42
November 2011
