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Honored Contributor
Honored Contributorinterface ADC0804 with CPLD
Hello Folks,
I am trying to interface the ADC0804, 8-bit output to 8 input pins of a CPLD. I intend to provide 1MHz clock frequency to the ADC and use a system clock for the CPLD at a lower frequency say 500 kHz. The reasoning bieng the ADC will have plenty of time to change its value within a system clock cycle. I have looked at the control steps for the ADC and have attempted to initiate a start conversion cycle. Could someone please let me know if I am going about this correctly. Thank you in advance. The code is not complete as it does not read the value yet. I have to convert the crystal frequency of 25MHz into a squarewave in code.2 Replies
Altera_ForumThat... will not work.
What you have can be summarized as (in a cleaner way)
Don't abuse "buffer". Use "in", "out" and "inout" as needed. You mention that you want 1 MHz for the ADC and 500 kHz for the CPLD, but in your code, logic is running in the (negated) input clock, not in the divided by 2 "clk".clk_out <= not clk_in; process(clk_out) begin if(clk_out'event and clk_out='1') then count <=count+1; if(count = 5) then clk <= not clk; count <= 1; -- cs <= '0'; -- overriden -- wr<='0'; -- overriden wr<='0'; cs<='1'; if(intr = '0') then flag <= '1'; end if; end if; end if; end process;- Altera_Forum
Thank you very much for your advice, I have tried to correct the mistakes. Could you please have a quick look at this version.:)
