© August 2008 Altera Corporation
DSP Development Kit, Cyclone III Edition Getting Started User Guide
Preliminary
5. Factory Designs
Understanding the Factory Design
In the factory design, two sine waves are generated by two instances of the Altera
numerically controlled oscillator (NCO) MegaCore. One of these oscillators is running
at 10 times the frequency of the other, but both of them have the same amplitude, each
covering 13 bits of dynamic range. The two sine waves output from these blocks are
converted from two’s complement binary to unsigned binary format. They are then
added together. This combined sine wave signal of 14-bits dynamic range is sent to a
14-bit D/A converter. The analog output of a D/A converter is connected, by means
of the included SMA cable, with the analog input of a 14-bit A/D converter. The A/D
converter’s digital output is looped back to the Cyclone III device. The A/D is
configured by the dip switches to deliver the data in unsigned format. The converted
loopback data is captured by an instance of the SignalTap
®
II logic analyzer in the
design for display and analysis.
shows a high-level view of the factory design and how it interacts with the
D/A and A/D converters on the Data Conversion HSMC in the following sections.
1
The design files for the factory design are installed from the DSP Development Kit,
Cyclone III Edition CD-ROM in the directory: <
path
>\
kits\
cycloneIII_3c120_dsp\examples\cycloneIII_3c120_dsp_example_ChA
.
Figure 5–1.
Factory Design Functional Block Diagram
PLL
50 MHz
100 MHz
Cyclone III Development Board
1-MHz NCO
HSMC
Connector
DA
Data Conversion
HSMC
10-MHz NCO
3-MHz FIR
Filter
Data Inp
u
t
Latch
FIR
DB
14-
b
it
DAC B
14-
b
it
ADC A
