参考链接

https://blog.csdn.net/jbb0523/article/details/6946899

出错原因

两个Process都对LDS_temp进行了赋值,万一在某个时刻,在两个Process中对LDS_temp赋值条件都满足,那么你让FPGA该怎么做呢?让它听谁哪个Process块的呢?

报错

ISE14.7 综合时报错

ERROR:HDLCompiler:1401 - "D:\project\ISEProject\FlowingLED\LED.vhd" Line 23: Signal LDS_temp[7] in unit LED is connected to following multiple drivers:
Driver 0: output signal LDS_temp[7] of instance Flip-flop (LDS_temp).
Driver 1: output signal LDS_temp[7] of instance Latch (LDS_temp[7]).
Driver 0: output signal LDS_temp[6] of instance Flip-flop (LDS_temp).
Driver 1: output signal LDS_temp[6] of instance Latch (LDS_temp[6]).
Driver 0: output signal LDS_temp[5] of instance Flip-flop (LDS_temp).
Driver 1: output signal LDS_temp[5] of instance Latch (LDS_temp[5]).
Driver 0: output signal LDS_temp[4] of instance Flip-flop (LDS_temp).
Driver 1: output signal LDS_temp[4] of instance Latch (LDS_temp[4]).
Driver 0: output signal LDS_temp[3] of instance Flip-flop (LDS_temp).
Driver 1: output signal LDS_temp[3] of instance Latch (LDS_temp[3]).
Driver 0: output signal LDS_temp[2] of instance Flip-flop (LDS_temp).
Driver 1: output signal LDS_temp[2] of instance Latch (LDS_temp[2]).
Driver 0: output signal LDS_temp[1] of instance Flip-flop (LDS_temp).
Driver 1: output signal LDS_temp[1] of instance Latch (LDS_temp[1]).
Driver 0: output signal LDS_temp[0] of instance Flip-flop (LDS_temp).
Driver 1: output signal LDS_temp[0] of instance Latch (LDS_temp[0]).
-->

出错代码

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL; -- Flowing LED
-- 先分频再移位
entity LED is
port(
GCLK,BTNU:in std_logic;
LDS:out std_logic_vector(7 downto 0)
);
end LED; architecture Behavioral of LED is
-- 计数
signal count:std_logic_vector(25 downto 0);
signal clk_temp:std_logic;
signal Q_temp:std_logic;
signal LDS_temp:std_logic_vector(7 downto 0):="00000001";
begin process(GCLK,BTNU)
--分频系数
variable N :std_logic_vector(25 downto 0):="10111110101111000010000000";
begin
if BTNU='1' then
count<="00000000000000000000000001";
clk_temp<='1';
LDS_temp<= "00000001";
elsif (GCLK'EVENT and GCLK='1')then
if (count=N)then
count<="00000000000000000000000001";
clk_temp<='1';
else
count<=count+1;
clk_temp<='0';
end if;
end if;
end process;
--得到的clk_temp为2Hz,占空比1/50000000 process(clk_temp)
begin
if (clk_temp'EVENT and clk_temp='1')then
LDS_temp(7)<=Q_temp;
LDS_temp(6 downto 0)<=LDS_temp(7 downto 1);
--Q_temp<=LDS_temp(0);
end if;
end process;
LDS<=LDS_temp;
end Behavioral;

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