DAC5672 Sine output

I havent read anything about 14-bit inputs being 1's complement .

The only mention about the inputs is given in the attached screen shot .

The 14-bit digital data input fallows the offset positive binary coding scheme.

Your turn to google now.

Thanks for the guidance, now i need a VHDL function to convert 14-bit std_logic into off-set binary code, any ideas ?

:)

Here's how i am changing values in VHDL

ADJUSTING_OFFSET: PROCESS(sys_clk, sin_out_reg)

BEGIN

IF reset_n = '0' THEN

sin_out_adj <= (others=>'0');

ELSIF rising_edge(sys_clk) THEN

IF nco_sin_out(13) = '1' THEN

sin_out_adj <= NOT(nco_sin_out)+"00000000000001";

ELSE

sin_out_adj<= '1'& nco_sin_out(12 downto 0);

END IF;

END IF;

-- END IF;

END PROCESS;

But i am not getting a clean sine wave out ?? the frequency of generated signal is correct

see image attached

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Here's how i am changing values in VHDL

ADJUSTING_OFFSET: PROCESS(sys_clk, sin_out_reg)

BEGIN

IF reset_n = '0' THEN

sin_out_adj <= (others=>'0');

ELSIF rising_edge(sys_clk) THEN

IF nco_sin_out(13) = '1' THEN

sin_out_adj <= NOT(nco_sin_out)+"00000000000001";

ELSE

sin_out_adj<= '1'& nco_sin_out(12 downto 0);

END IF;

END IF;

-- END IF;

END PROCESS;

But i am not getting a clean sine wave out ?? the frequency of generated signal is correct

see image attached

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To change 2's complement to offset binary just invert the sign bit.

sign_inv = not data(13);

data <= sign_inv & data(12 downto 0);

keep this combinatorial to avoid latency problems

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Hi All,

I am trying to generate a simple Sine wave from DAC5672 on my Hsmc daughter card from Terasic . The NCO i am using is from Open Cores , i works fine in simulation as shown in screen shot attached , But when i connect my scope probes i get distorted output screen shot attached . The DAC and NCO are provided with 100Mhz clock and the required output is 12Mhz , which is in my case is 12Mhz but distorted .

When is connect a simple upcounter , i get a Saw tooth wave output as expected .

Has anyone solved this problem ? is there something i am missing ?

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I can not send a private message to ask you a question.

I'm in exactly the same situation how you have resolved the problem?

my email yonatanhanann@gmail.com