串轉換

串轉換在實際的電路中使用比較多，尤其在通信線路方面的複用和分解方面，原理上就是一個串轉換和並轉換的過程。舉個簡單的例子，計算機串口發送數據的過程，如果滿足發送條件了，其實就是一個並串轉換的過程了。

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--Engineer:skycanny

--ModuleName:p2s-Behavioral

--Toolversions:ISE7.1

--Description:Thismoduleisdesignedtoimplementparalleltoserialconversion

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libraryIEEE;

useIEEE.STD_LOGIC_1164.ALL;

useIEEE.STD_LOGIC_ARITH.ALL;

useIEEE.STD_LOGIC_UNSIGNED.ALL;

entityp2sis

port(

reset:instd_logic;

clk:instd_logic;

start:instd_logic;--lowactive,data_invalid

data_in:instd_logic_vector(7downto0);

data_valid:outstd_logic;--highactive,outputdatavalid

ready:outstd_logic;--lowactive,readytorecievedata

q:outstd_logic

);

endp2s;

architectureBehavioralofp2sis

signalreg:std_logic_vector(7downto0);

signalcnt:std_logic_vector(3downto0);

signalreg_en:std_logic;

signalshift_start:std_logic;

typestateis(idle,recieve,shift,finish);

signalcurrent_state,next_state:state;

begin

counter:process(reset,clk,shift_start)

begin

if(reset='0')then

cnt'0');

elsif(clk'eventandclk='1')then

if(shift_start='0')then

cnt'0');

endif;

endif;

endprocesscounter;

fsm:block

begin

sync:process(reset,clk)

begin

if(reset='0')then

current_state

ready

reg_en

reg_en

reg_en

next_state'0');

q<='0';

elsif(clk'eventandclk='1')then

if(reg_en='0')then

reg<=data_in;

elsif(shift_start='0')then

q<=reg(7);

foriin7downto1loop--shiftregister

reg(i)<=reg(i-1);

endloop;

reg(0)<='0';

else

q<='0';

endif;

endif;

endprocessdata_channel;

endBehavioral;