BIT STUFFING........

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rakesh_aadhimoolam

Joined: 14 Mar 2006
Posts: 218
Helped: 16

14 Jul 2006 9:58 BIT STUFFING........

HELLO EVERYONE.............

i was doing a program on "bit stuffing"....
the q is "Design a bit stuffer. The circuit takes serial data in and gives serial data out. If in the input stream five consecutive 1’s or 0’s are detected than a ‘0’ or a ‘1’ is inserted in the stream respectively"

i tried to do the following program but though bit stuffing is processed but for
the next bits that are entered the re a bit loss..

how can i rectify it?

LIBRARY ieee;
USE ieee.std_logic_1164.ALL;

ENTITY BitStuffer IS
PORT
( serial_in :IN std_logic;
rst,clk :IN std_logic;
serial_out :IN std_logic;
);
END BitStuffer;

ARCHITECTURE arch OF Bitstuffer IS

begin
process(clk,rst,serial_in)
variable temp1 : std_logic(4 downto 0);
variable stuffbit:std_logic;
variable count:integer range 0 to 4;
begin
if(rst='1') then
temp:='0';
serial_out<='0';
count:=0;
elsif(clk'event and clk='1') then
case serial_in is
when 1=>
for i in 0 to 4 loop
temp(i):=temp(i+1);
temp(4):=serial_in;
count:=count+1;
if(count=5) then
stuffbit:='0';
else
count:='0';
end loop;
when 0=>
for i in 0 to 4 loop
temp(i):=temp(i+1);
temp(4):=serial_in;
count:=count+1;
if(count=5) then
stuffbit:='1';
else
count:='0';
end loop;

thank you.............

tkbits

Joined: 04 Dec 2004
Posts: 235
Helped: 36

16 Jul 2006 10:06 Re: BIT STUFFING........

You will lose bits if you don't control the shifting (external to BitStuffer) of serial_in. You need to stall the serial_in bit stream in order to provide the time to insert each one of the stuffing bits.

Last edited by tkbits on 17 Jul 2006 4:03; edited 4 times in total