Forum Discussion

Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
15 years ago

How to make DDS with NCO megacore function?

I try to make square wave with NCO Megacore Function as below. But, The square wave is not good for use like dds. How to make square wave like ad9850 dds ----- below is VHDL Code -------...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
15 years ago

The phase accu isn't more than 

accu :unsigned (NCO_W-1 downto 0); 
freq :unsigned (NCO_W-1 downto 0);
...
process(clk);
begin
if rising_edge(clk) then 
  accu <= accu + freq;
end if;
end process,
square <= freq(NCO_W-1);

Review the NCO MegaFunction manual for a detailed description.