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Frequency Generator for the Spartan-3E Starter Kit 13
Setting DCM Frequency Aligned Mode
To set the DCM into the frequency aligned mode of operation a special option must be used during configuration file generation. This can be set in the ISE
tools as shown in these screen shots from an ISE v8.1i project for this reference design.
-g cfg_dfs_s_x1y1:1111000011111111xxx111xxxxx1xxxxxxxxxx1xxxxxxxxxxxxxxxxxxxxxxxxxxxxx01000000
1) In the ‘Processes’ window select ‘Generate Programming File’. Then
right click and select ‘Properties’ to open the ‘Process Properties’ box.
2) The ‘Process Properties’ box should open with the ‘General Options’ being
shown (otherwise select ‘General Options’ on the left). Move to the line ‘Other
Bitgen Command Line Options’ and enter the text string shown below.
3) Select ‘Apply’ and then use ‘OK’ to exit the box.
Hint – Reopen the box and confirm the option really was set correctly.
Hint – You may need to set ‘Property display level’ to ‘Advanced’ and scroll down
to see this line.
Hint – The format of this special DCM
option are described in some detail in
the ‘frequency_generator.vhd’ file from
which you can also copy and paste to
avoid typing errors!