我在 Spartan 3E 入门套件中编写了两个用于实现 DAC 的代码，它们似乎在模拟中工作得很好，但是当我将它们连接到芯片示波器并加载到板上时，我总是得到一个零值。我还注意到没有严重警告。代码 1：
module dac_state_d(
input dacclk,
input reset,
input [31:0] dacdata,
output reg[31:0] previousdata,
output reg dac_mosi,
output reg dac_miso,
output reg dac_cs,
output reg dac_sck,
output reg dac_clr,
output reg spi_ss_b,
output reg sf_ce0,
output reg fpga_init_b,
output reg amp_cs,
output reg ad_conv,
output reg [2:0] state,
output reg ack
);
integer index=0;
parameter idle=3'b000, ready=3'b001, delay=3'b010, trans=3'b011, read=3'b100, increment=3'b101, check=3'b110;
initial begin//setting different registers on spi bus and initialization
spi_ss_b='b1;
amp_cs='b1;
ad_conv='b0;
sf_ce0='b1;
fpga_init_b='b0;
end
always @(posedge dacclk or posedge reset) begin
if (reset) begin
index<=0;
dac_mosi<=0;
dac_clr<=0;
dac_sck<=0;
dac_cs<=1;
end
else begin
dac_clr<=1;
case(state)
idle: begin
dac_sck <= 0;
dac_cs <= 1;
index <= 0;
dac_mosi <= 0;
ack <= 1;
state <= ready;
end
ready: begin
ack <= 0;
dac_cs <= 0;
dac_sck <= 0;
dac_mosi <= dacdata[31-index];
state <= delay;
end
delay: begin
state <= trans;
end
trans: begin
dac_sck <= 1;
state <= read;
end
read: begin
dac_sck <= 1;
previousdata[31-index]<=dac_miso;
state <= increment;
end
increment: begin
dac_sck <= 1;
index <= index + 1;
state <= check;
end
check: begin
dac_sck <= 1;
if (31-index < 0) begin
state <= idle; end
else begin
state <= ready;
end
end
endcase
end
end
endmodule
其顶层模块定义为
reg [31:0] dacdata;
wire [31:0] previousdata;
reg [3:0] command, address;
wire dac_miso_w;
assign dac_miso_w=dac_miso;
wire dacclk;
DACCLK clock(.clk(clk),
.dacclk(dacclk)
);
dac_state_d daq_run(.dacclk(dacclk),
.reset(reset),
.dacdata(dacdata),
.previousdata(previousdata),
.dac_mosi(dac_mosi),
.dac_miso(dac_miso_w),
.dac_clr(dac_clr),
.dac_cs(dac_cs),
.spi_ss_b(spi_ss_b),
.sf_ce0(sf_ce0),
.fpga_init_b(fpga_init_b),
.amp_cs(amp_cs),
.ad_conv(ad_conv),
.dac_sck(dac_sck),
.state(state),
.ack(ack)
);
initial begin
command<=4'b0011;
address<=4'b1111;
end
always @ (posedge clk) begin
if (ack) begin
dacdata[31:24]<=8'b00000000;
dacdata[23:20]<=command;
dacdata[19:16]<=address;
dacdata[15:4]<=data;
dacdata[3:0]<=4'b0000;
pre_data<=previousdata[15:4];
end
else begin dacdata<=0; end
end
//chipscope-------------------
wire[11:0] D;
wire R;
wire[35:0] CONTROL;
assign D=data;
assign R=reset;
ICON cs_con(.CONTROL0(CONTROL)); //INOUT BUS [35:0]
VIO cs_vio (.CONTROL(CONTROL), // INOUT BUS [35:0]
.ASYNC_IN({pre_data,state,ack}), // IN BUS [12:0]
.ASYNC_OUT({D,R}) // OUT BUS [12:0]
);
//----------------------------------------------------------------------------
endmodule
显然顶级模块也有 I/O 端口描述。
代码 2：
wire dacclk;
DACCLK clock(.clk(clk),
.dacclk(dacclk)
);
initial begin//setting different registers on spi bus and initialization
spi_ss_b='b1;
amp_cs='b1;
ad_conv='b0;
fpga_init_b='b0;
dac_clr=1;
dac_cs=1;
dacstate<=0;
//StrataFLASH must be disabled to prevent it driving the SDI line with its D0 output
//or conflicting with the LCD display
strataflash_oe <= 1;
strataflash_ce <= 1;
strataflash_we <= 1;
end
always@(posedge dacclk) begin
case (dacstate)
//------------------------------Bit 31 to 24 Don't Care----------------------------------
0: begin//idle and allotment cycle(31-->x)
ack=0;
dac_cs=0;
dac_sck=0;
dacstate=1;
end
1: begin//read write cycle (31)
dac_sck=1;
dacstate=2;
end
2: begin//idle and allotment cycle(30-->x)
dacstate=3;
dac_sck=0;
end
3: begin//read write cycle(30)
dac_sck=1;
dacstate=4;
.....
62: begin//idle and allotment cycle(0-->x)
dac_sck=0;
dacstate=63;
end
63: begin//read write cycle(0)
dac_sck=1;
dacstate=64;
end
64: begin//Acknowledging completion of data transfer to DAC
dac_cs=1;
ack=1;
dacstate=65;
end
65: begin if (reset) begin dacstate=0; end
else begin dacstate=65; end end//idle or reset
default: begin dacstate=0; end
endcase
end
endmodule
我使用的UCF文件如下
NET "clk" PERIOD = 20.0ns HIGH 50%;
NET "clk" LOC = "C9" | IOSTANDARD = LVTTL;
NET"dac_miso" LOC= "N10" | IOSTANDARD= LVCMOS33 ;
NET"dac_mosi" LOC= "T4" | IOSTANDARD= LVCMOS33 | SLEW= SLOW | DRIVE= 8 ;
NET"dac_sck" LOC= "U16" | IOSTANDARD= LVCMOS33 | SLEW= SLOW | DRIVE= 8 ;
NET"dac_cs" LOC= "N8" | IOSTANDARD= LVCMOS33 | SLEW= SLOW | DRIVE= 8 ;
NET"dac_clr" LOC= "P8" | IOSTANDARD= LVCMOS33 | SLEW= SLOW | DRIVE= 8 ;
NET "fpga_init_b" LOC = "T3" | IOSTANDARD = LVCMOS33 | SLEW = SLOW | DRIVE = 4 ;
NET "ad_conv" LOC = "P11" | IOSTANDARD = LVCMOS33 | SLEW = SLOW | DRIVE = 6 ;
NET "amp_cs" LOC = "N7" | IOSTANDARD = LVCMOS33 | SLEW = SLOW |DRIVE = 6 ;
NET "spi_ss_b" LOC = "U3" | IOSTANDARD = LVCMOS33 | SLEW = SLOW | DRIVE = 6 ;
NET "sf_ce0" LOC = "D16" | IOSTANDARD = LVTTL | SLEW = SLOW | DRIVE = 2;
NET "reset" LOC = "V4" | IOSTANDARD = LVTTL | PULLDOWN;
我不指望有人能解决我的问题，但我感到无助，因为我正在调试过去 2 周以来的这些代码，但我找不到任何问题。如果有人能指出我的错误，那将非常有帮助。我还浏览了一些示例代码，但由于所有代码都是用 VHDL 编写的，因此它们对我没有太大帮助。我仍然尝试匹配逻辑并发现它是相同的。