verilog串口通信实现pc发送一个字符给fpga，fpga收到以后，发送另外一串字符串给电脑应答。

Question

我写的代码只能实现发送字符与收到字符一样。

Answer 1

你写的代码有问题呗。。。
Library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_arith.all;
use ieee.std_logic_unsigned.all;

entity atel2_bin is
port(
txclk: in std_logic; --2400Hz的波特率时钟
reset: in std_logic; --复位信号
din: in std_logic_vector(15 downto 0); --发送的数据
start: in std_logic; --允许传输信号
sout: out std_logic --串行输出端口
);
end atel2_bin;

architecture behav of atel2_bin is
signal thr,len: std_logic_vector(15 downto 0);
signal txcnt_r: std_logic_vector(2 downto 0); --数据位计数
signal sout1: std_logic;
signal cou: integer:=0;
signal oddb:std_logic;
type s is(start1,start2,shift1,shift2,odd1,odd2,stop1,stop2);
signal state:s:=start1;
begin

process(txclk)
begin
if rising_edge(txclk) then
if cou<3 then
thr<=0000000001010101; --发送的文件头
elsif cou=3 then
thr<=0000000000000010; --发送的文件长度
elsif (cou>3 and state=stop2) then
thr<=din;--发送的数据
end if;
end if;
end process;

process(reset,txclk)
variable tsr,tsr1,oddb1,oddb2: std_logic_vector(7 downto 0);
begin
if reset=1 then
txcnt_r<=(others=>0);
sout1<=1;
state<=start1;
cou<=0;
elsif txclkevent and txclk=1 then
case state is
when start1=> ----低8位
if start=1 then
if cou=3 then
len<=thr;
end if;
tsr:=thr(7 downto 0);
oddb1:=thr(7 downto 0);
sout1<=0; --起始位
txcnt_r<=(others=>0);
state<=shift1;
else
state<=start1;
end if;
when shift1=>
oddb<=oddb1(7) xor oddb1(6) xor oddb1(5) xor oddb1(4) xor oddb1(3) xor oddb1(2) xor oddb1(1) xor oddb1(0);
sout1<=tsr(0); --数据位
tsr(6 downto 0):=tsr(7 downto 1);
tsr(7):=0;
txcnt_r<=txcnt_r+1;
if (txcnt_r=7) then
state<=odd1;cou<=cou+1;
end if;
when odd1=> --奇校验位
if oddb=1 then
sout1<=0; state<=stop1;
else
sout1<=1; state<=stop1;
end if;
when stop1=>
sout1<=1; --停止位
if cou<4 then
state<=start1;
else
state<=start2;
end if;

when start2=> ----高8位
tsr1:=thr(15 downto 8);
oddb2:=thr(15 downto 8);
sout1<=0; --起始位
txcnt_r<=(others=>0);
state<=shift2;
when shift2=>
oddb<=oddb2(7) xor oddb2(6) xor oddb2(5) xor oddb2(4) xor oddb2(3) xor oddb2(2) xor oddb2(1) xor oddb2(0);
sout1<=tsr1(0); --数据位
tsr1(6 downto 0):=tsr1(7 downto 1);
tsr1(7):=0;
txcnt_r<=txcnt_r+1;
if (txcnt_r=7) then
state<=odd2;
end if;
when odd2=> --奇校验位
if oddb=1 then
sout1<=0;state<=stop2;
else
sout1<=1;state<=stop2;
end if;
when stop2=>
sout1<=1; --停止位
if len=0000000000000000 then
state<=stop2;
else
state<=start1;
len<=len-1;
end if;
end case;
end if;
end process;

sout<=sout1;

end behav;

追问

你这是vhdl 不是我想要的