OBUFDS or OBUFDS_LVDS ?? plz help me about differential signal 1

[jackseiko]

hi,

I need to use [LVDS(350 mV)] differential signal input/output at my project . But I have no experience about using differential signal,
do I need to use OBUFDS or OBUFDS_LVDS component ???

I'd be grateful if u give me very little example of usage of this components. Thanks in advance


-------------------------------------------------

for example

entity transmitter is

port (
clock: in std_logic;
reset : in std_logic; -- system reset
Data_out_p : out std_logic; -- differential data output
Data_out_n : out std_logic; -- differential data output


);
end transmitter;

architecture Behavioral of transmitter is

OBUFDS : OBUFDS port map ( -------------- will it be like that ? ---------------
O => ??, -- Buffer output
I => data_out_p,
IB => data_out_n);
);


begin


);

 

[BertVhdl]

Hi Jckseiko,

You can just use the OBUFDS (Output buffer differantial). Use it as followes:

entity transmitter is

port (
  clock      : in  std_logic;
  reset      : in  std_logic; -- system reset
  Data_out_p : out std_logic; -- differential data output
  Data_out_n : out std_logic  -- differential data output
);
end transmitter;

architecture Behavioral of transmitter is

  signal your_signal : std_logic;

begin

  <inst_name> : OBUFDS 
  port map(
    O  => your_signal, -- Buffer output
    I  => data_out_p,
    IB => data_out_n
  );

end Behavioral;

You can then drive the LVDS output by driving your_signal. Remember to tell ISE (Xilinx I guess) that it is LVDS. This is easily done in the constraint file (UCF file).

Also notice some syntax errors I removed and the position of the OBUFDS, after the BEGIN statement.

To use this component you also need to use the Xilinx unisim library.

Bert

 

[jackseiko]

thank you so much, it really helps