Evaluation Board
User Guide
Rev. A | Page 12 of 14
Use the
Rising Step Size
and
Falling Step Size
checkboxes to
set the step size of the rising or falling ramp. The unit for these
changes depending on what type of ramp is being generated.
The
Rising Sweep Ramp Rate
and
Falling Sweep Ramp
Rate
are used to set the time between each rising or falling step
on the ramp. This is in units of microseconds.
The
No Dwell High
and
No Dwell Low
boxes set the
corresponding bit functions in the register map. Use the Up,
Down, and Pause buttons at the bottom of the window to
control the direction or to hold the ramp. The Ramp Finished
indicator turns on when the ramp is complete.
PROGRAMMABLE MODULUS WINDOW
Figure 13. Programmable Modulus Window
The chip is in programmable modulus mode when the
Enable
Programmable Modulus
check box is selected. The digital
ramp generator mode will automatically be disabled.
The
Programmable Modulus
window is used to alter the
frequency equation of the DDS core, making it possible to
implement fractions that are not restricted to a power of 2 in the
denominator.
When you enter the desired output frequency (in terms of
MHz) in the
Fout
box, the values in the
Register Value
s boxes
and the
Divide Ratio
boxes are automatically updated. You can
also directly input a divide ratio, which in this case will
automatically update the R
egister Values
boxes and
the
Output Frequency
box.
