【发布时间】：2021-07-11 13:55:41
【问题描述】：
我不太擅长编程 vhdl，我遇到了这个错误：
Error (10818): Can't infer register for "Current_Number_32[0]" at Receiver.vhd(123) because it does not hold its value outside the clock edge
Error (10818): Can't infer register for "Current_Number_32[1]" at Receiver.vhd(123) because it does not hold its value outside the clock edge
Error (10818): Can't infer register for "Current_Number_32[2]" at Receiver.vhd(123) because it does not hold its value outside the clock edge
Error (10818): Can't infer register for "Current_Number_32[3]" at Receiver.vhd(123) because it does not hold its value outside the clock edge
Error (10818): Can't infer register for "Current_Number_32[4]" at Receiver.vhd(123) because it does not hold its value outside the clock edge
Error (10818): Can't infer register for "Current_Number_32[5]" at Receiver.vhd(123) because it does not hold its value outside the clock edge
Error (10818): Can't infer register for "Current_Number_32[6]" at Receiver.vhd(123) because it does not hold its value outside the clock edge
Error (10818): Can't infer register for "Current_Number_32[7]" at Receiver.vhd(123) because it does not hold its value outside the clock edge
Error (10818): Can't infer register for "Current_Number_32[8]" at Receiver.vhd(106) because it does not hold its value outside the clock edge
Error (10818): Can't infer register for "Current_Number_32[9]" at Receiver.vhd(106) because it does not hold its value outside the clock edge
Error (10818): Can't infer register for "Current_Number_32[10]" at Receiver.vhd(106) because it does not hold its value outside the clock edge
Error (10818): Can't infer register for "Current_Number_32[11]" at Receiver.vhd(106) because it does not hold its value outside the clock edge
Error (10818): Can't infer register for "Current_Number_32[12]" at Receiver.vhd(106) because it does not hold its value outside the clock edge
Error (10818): Can't infer register for "Current_Number_32[13]" at Receiver.vhd(106) because it does not hold its value outside the clock edge
Error (10818): Can't infer register for "Current_Number_32[14]" at Receiver.vhd(106) because it does not hold its value outside the clock edge
Error (10818): Can't infer register for "Current_Number_32[15]" at Receiver.vhd(106) because it does not hold its value outside the clock edge
Error (10818): Can't infer register for "Current_Number_32[16]" at Receiver.vhd(89) because it does not hold its value outside the clock edge
Error (10818): Can't infer register for "Current_Number_32[17]" at Receiver.vhd(89) because it does not hold its value outside the clock edge
Error (10818): Can't infer register for "Current_Number_32[18]" at Receiver.vhd(89) because it does not hold its value outside the clock edge
代码：
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
USE IEEE.STD_LOGIC_UNSIGNED.ALL;
entity Receiver is
Port ( SYS_CLK : in STD_LOGIC;
RST : in STD_LOGIC;
DATA_ACK : out STD_LOGIC;
DATA_VALID : in STD_LOGIC;
DATA_BUS_8 : in STD_LOGIC_VECTOR (7 downto 0);
DIGIT_1 : out STD_LOGIC_VECTOR (6 downto 0);
DIGIT_2 : out STD_LOGIC_VECTOR (6 downto 0);
DIGIT_3 : out STD_LOGIC_VECTOR (6 downto 0);
DIGIT_4 : out STD_LOGIC_VECTOR (6 downto 0);
DIGIT_5 : out STD_LOGIC_VECTOR (6 downto 0);
DIGIT_6 : out STD_LOGIC_VECTOR (6 downto 0);
DIGIT_7 : out STD_LOGIC_VECTOR (6 downto 0);
DIGIT_8 : out STD_LOGIC_VECTOR (6 downto 0));
end Receiver;
architecture Behavioral of Receiver is
signal Current_Number_32 : STD_LOGIC_VECTOR (31 downto 0) := (others => '0');
function BitsToDisplay (Bits : STD_LOGIC_VECTOR (3 downto 0) := (others => '0')) return STD_LOGIC_VECTOR is
variable DisplayBits : STD_LOGIC_VECTOR (6 downto 0);
begin
case Bits is
when "0000" => DisplayBits := "1111110";
when "0001" => DisplayBits := "0110000";
when "0010" => DisplayBits := "1101110";
when "0011" => DisplayBits := "1111001";
when "0100" => DisplayBits := "0110011";
when "0101" => DisplayBits := "1011011";
when "0110" => DisplayBits := "1011111";
when "0111" => DisplayBits := "1110000";
when "1000" => DisplayBits := "1111111";
when "1001" => DisplayBits := "1111101";
when "1010" => DisplayBits := "1110111";
when "1011" => DisplayBits := "0011111";
when "1100" => DisplayBits := "1001111";
when "1101" => DisplayBits := "0111101";
when "1110" => DisplayBits := "1001111";
when "1111" => DisplayBits := "1000111";
when others => DisplayBits := "0000001";
end case;
return DisplayBits;
end function;
begin
Communication : process (SYS_CLK,RST,DATA_ACK,DATA_VALID,DATA_BUS_8)
variable Section_1 : STD_LOGIC_VECTOR (7 downto 0) := (others => '0');
variable Section_2 : STD_LOGIC_VECTOR (7 downto 0) := (others => '0');
variable Section_3 : STD_LOGIC_VECTOR (7 downto 0) := (others => '0');
variable Section_4 : STD_LOGIC_VECTOR (7 downto 0) := (others => '0');
variable Current_Section : STD_LOGIC_VECTOR (1 downto 0) := (others => '0');
variable Stage : STD_LOGIC_VECTOR (1 downto 0) := (others => '0');
begin
if (RST = '1') then
DATA_ACK <= '0';
Current_Number_32 <= (others => '0');
Section_1 := (others => '0');
Section_2 := (others => '0');
Section_3 := (others => '0');
Section_4 := (others => '0');
Current_Section := (others => '0');
Stage := (others => '0');
elsif rising_edge(SYS_CLK) then
if (Current_Section = "00") then
if (Stage = "00") and rising_edge(DATA_VALID) then
Section_1 := DATA_BUS_8;
Stage := "01";
end if;
if (Stage = "01") and (DATA_ACK = '1') then
DATA_ACK <= '0';
Stage := "00";
Current_Section := "01";
end if;
if (Stage = "01") and falling_edge(DATA_VALID) then
DATA_ACK <= '1';
end if;
end if;
if (Current_Section = "01") then
if (Stage = "00") and rising_edge(DATA_VALID) then
Section_2 := DATA_BUS_8;
Stage := "01";
end if;
if (Stage = "01") and (DATA_ACK = '1') then
DATA_ACK <= '0';
Stage := "00";
Current_Section := "10";
end if;
if (Stage = "01") and falling_edge(DATA_VALID) then
DATA_ACK <= '1';
end if;
end if;
if (Current_Section = "10") then
if (Stage = "00") and rising_edge(DATA_VALID) then
Section_3 := DATA_BUS_8;
Stage := "01";
end if;
if (Stage = "01") and (DATA_ACK = '1') then
DATA_ACK <= '0';
Stage := "00";
Current_Section := "11";
end if;
if (Stage = "01") and falling_edge(DATA_VALID) then
DATA_ACK <= '1';
end if;
end if;
if (Current_Section = "11") then
if (Stage = "00") and rising_edge(DATA_VALID) then
Section_4 := DATA_BUS_8;
Stage := "01";
end if;
if (Stage = "01") and (DATA_ACK = '1') then
Current_Number_32(31 downto 24) <= Section_1;
Current_Number_32(23 downto 16) <= Section_2;
Current_Number_32(15 downto 8) <= Section_3;
Current_Number_32(7 downto 0) <= Section_4;
DATA_ACK <= '0';
Stage := "00";
Current_Section := "00";
end if;
if (Stage = "01") and falling_edge(DATA_VALID) then
DATA_ACK <= '1';
end if;
end if;
end if;
end process Communication;
Display : process (SYS_CLK,RST,DIGIT_1,DIGIT_2,DIGIT_3,DIGIT_4,DIGIT_5,DIGIT_6,DIGIT_7,DIGIT_8)
begin
if (RST = '1') then
DIGIT_8 <= (others => '0');
DIGIT_7 <= (others => '0');
DIGIT_6 <= (others => '0');
DIGIT_5 <= (others => '0');
DIGIT_4 <= (others => '0');
DIGIT_3 <= (others => '0');
DIGIT_2 <= (others => '0');
DIGIT_1 <= (others => '0');
else
DIGIT_8 <= BitsToDisplay(Current_Number_32(3 downto 0));
DIGIT_7 <= BitsToDisplay(Current_Number_32(7 downto 4));
DIGIT_6 <= BitsToDisplay(Current_Number_32(11 downto 8));
DIGIT_5 <= BitsToDisplay(Current_Number_32(15 downto 12));
DIGIT_4 <= BitsToDisplay(Current_Number_32(19 downto 16));
DIGIT_3 <= BitsToDisplay(Current_Number_32(23 downto 20));
DIGIT_2 <= BitsToDisplay(Current_Number_32(27 downto 24));
DIGIT_1 <= BitsToDisplay(Current_Number_32(31 downto 28));
end if;
end process Display;
end Behavioral;
谁能解释我在这里做错了什么？ 我已经将此代码作为一个块添加到具有其他两个代码的框图中，但在我这样做之前编译没有发现错误。 这段代码不需要在实际的 fpga 上运行，因为这是一个学校作业，所以我只需要模拟它。这会消除这个错误吗？
【问题讨论】：
-
你用的是什么工具？快速浏览一下，错误看起来很奇怪，因为显然应该推断出寄存器。我建议您不要使用任何变量，而只使用信号。它们的行为彼此不同，变量可以纯粹根据进程中的代码顺序创建不同的电路。因此，作为初学者，我建议不要使用变量。
-
这可能与变量有关。您可以尝试将所有这些阶段变量重构为信号吗？重置它们也不会做任何事情