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Altera_Forum
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16 years ago

Deserialization 12 bits LVDS in a Cyclone III

I am using Quartus II 8.0 for programming a Cyclone III device. I have 2 LVDS clocks (fclk and lclk) an an 8 channel (12 bit) LVDS input that I wish to deserialize.

The megafunction for deserialization does not work for 12 bit data.

Will I program my component in VHDL to deserialize in 12 bits, or can I use some other components to make this (DDIO, multiplex,DFF...) ? I'm using SOPC Builder.

thanks

5 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    I can share a simple deserializer utilizing DDIO: 

    chan:
FOR I IN 0 TO 7 GENERATE
  lvds_rcv : altddio_in
  GENERIC MAP (
    intended_device_family => "Cyclone III",
    invert_input_clocks => "ON",
    lpm_type => "altddio_in",
    power_up_high => "OFF",
    width => 1)
  PORT MAP (
    datain => AD9222_D(I TO I),
    inclock => fastclock,
    dataout_h => dataout_h(I DOWNTO I),
    dataout_l => dataout_l(I DOWNTO I));
PROCESS (fastclock)
  BEGIN
    IF rising_edge(fastclock) THEN
      lvds_sr(I) <= lvds_sr(I)(9 downto 0) & dataout_l(I) & dataout_h(I);
    END IF;
  END PROCESS;
PROCESS (slowclock)
  BEGIN
    IF reset = '1' THEN
       lvds_rx(I) <= (others => '0');
    ELSIF rising_edge(slowclock) THEN
       lvds_rx(I) <= lvds_sr(I);
    END IF;
END PROCESS;
END GENERATE;
  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    i believe you can type 12 into the MegaWizard even though it doesn't have a pull down for this value.

  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    Yes, that's true, if I remember right. I have my own deserializer, because I don't like the restrictions in phase setup of the "soft" LVDS MegaFunction and the strange RTL it offers for 14-Bit operation.

  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    Thank you people.

    But, if I program my own deser, I will need to desenvolve a driver for Nios ( I need to run the program in Nios for interface with a memory).

    I need to edit a component of Mega Wizard and to try interface it, with a PIO for use it in Nios.

    If I use the altlvds component with 2 channels and factor 6 ( width 12), I will have physically two inputs, and I need connect both in a same entrance, how I made this with no error in quartus ?
  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    Factor 6 isn't correct. As thepancake suggested, you can simply type in a factor of 12 in the MegaWizard setup