题
下面的代码从Xilinx应用程序注释中实现了Verilog中的Delta-Sigma DAC,我想编写等效的VHDL代码。我对Verilog一无所知,我在VHDL的初学者,因此我必须做出很多猜测,可能是初学者错误(下面代码)。我不确定翻译是否正确,有人可以帮忙吗?
原始Verilog
`timescale 100 ps / 10 ps
`define MSBI 7
module dac(DACout, DACin, Clk, Reset);
output DACout;
reg DACout;
input [`MSBI:0] DACin;
input Clk;
input Reset;
reg [`MSBI+2:0] DeltaAdder;
reg [`MSBI+2:0] SigmaAdder;
reg [`MSBI+2:0] SigmaLatch;
reg [`MSBI+2:0] DeltaB;
always @(SigmaLatch) DeltaB = {SigmaLatch[`MSBI+2], SigmaLatch[`MSBI+2]} << (`MSBI+1);
always @(DACin or DeltaB) DeltaAdder = DACin + DeltaB;
always @(DeltaAdder or SigmaLatch) SigmaAdder = DeltaAdder + SigmaLatch;
always @(posedge Clk or posedge Reset)
begin
if(Reset)
begin
SigmaLatch <= #1 1'bl << (`MSBI+1);
DACout <= #1 1'b0;
end
else
begin
SigmaLatch <== #1 SigmaAdder;
DACout <= #1 SigmaLatch[`MSBI+2];
end
end
endmodule
我在VHDL中的尝试:
entity audio is
generic(
width : integer := 8
);
port(
reset : in std_logic;
clock : in std_logic;
dacin : in std_logic_vector(width-1 downto 0);
dacout : out std_logic
);
end entity;
architecture behavioral of audio is
signal deltaadder : std_logic_vector(width+2 downto 0);
signal sigmaadder : std_logic_vector(width+2 downto 0);
signal sigmalatch : std_logic_vector(width+2 downto 0);
signal deltafeedback : std_logic_vector(width+2 downto 0);
begin
deltafeedback <= (sigmalatch(width+2), sigmalatch(width+2), others => '0');
deltaadder <= dacin + deltafeedback;
sigmaadder <= deltaadder + sigmalatch;
process(clock, reset)
begin
if (reset = '1') then
sigmalatch <= ('1', others => '0');
dacout <= '0';
elsif rising_edge(clock) then
sigmalatch <= sigmaadder;
dacout <= sigmalatch(width+2);
end if;
end process;
end architecture;
解决方案
看起来您正在使用ieee.std_logic_unsigned(或_arith)或两者兼而有之。
请不要那样做. 。利用 ieee.numeric_std.all
反而。
我的Verilog相当不存在,所以我忘记了Verilog是否默认为签名或未签名的算术...但是无论是哪个 signed
或者 unsigned
匹配的类型。
您的重置条款可能想阅读类似的内容:
sigmalatch <= (width+1 => '1', others => '0');
而且DeltaFeedBack更新类似:
deltafeedback(width+2 downto width+1) <= sigmalatch(width+2) & sigmalatch(width+2);
deltafeedback(width downto 0) <= (others => '0');
最后,为了匹配Verilog,我想您 width
通用应称为 MSBI
并设置为7(或更改您的所有 width+2
S到 width+1
S与您的意图相匹配 width
通用的)
其他提示
如果您只是对VHDL中的Delta-Sigma DAC感兴趣,则可以查看我的实现 Alt.Sources (请选择“原始消息”,保存到文件并在其上运行“ unshar”以获取来源)。
Wojtek
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