從SRAM中讀寫一個數據問題——Verilog 操作SRAM(IS63lv1024)，向SRAM寫入一個數據；并從SRAM中讀出數據；如果讀出的數據與寫入的一樣，說明寫讀成功，LED2閃爍，否則，SRAM操作不成功。
現在一直沒有實驗成功，請高手指教，謝謝！

HDL語言：VERILOG
CPLD芯片：XC95144XL-10T100I
SRAM芯片：IS63lv1024
晶振：40M
LED2電路已經可行。

以下是程序：
module OprateSRAM(clk,key,Addr_OUT,_CE_OUT,_OE_OUT,_WE_OUT,LED2_Flash,LED5_Flash,DMX_out1,DATA_INOUT);
input clk;
input key;
output _CE_OUT;
output _OE_OUT;
output _WE_OUT;
output LED2_Flash;
output LED5_Flash;
output DMX_out1;
output[15:0] Addr_OUT;
inout[7:0] DATA_INOUT;
reg [15:0] Addr_OUT_reg;
reg _CE_OUT_reg;
reg _OE_OUT_reg;
reg _WE_OUT_reg;
reg DMX_out1_reg;
reg [7:0] DATA_WRITE_BUFFER;
wire [7:0] DATA_READ_BUFFER;
reg [7:0] DATA_READ_BUFFER2;
wire r_en = _WE_OUT & (~_CE_OUT) & (~_OE_OUT);
wire w_en = (~_WE_OUT) & (~_CE_OUT);

//reg SRAM_RE_WR_OK;
reg LED2_Flash_reg_1Hz_buffer; // buffer,middile
reg LED2_Flash_reg; ?? ??? // putout
reg [21:0] LED2_Flash_1Hz_count; // count
reg LED5_Flash_reg;
reg [5:0] state;
reg WR_RD_Return;
parameter
IDLE ?? = 6'b000_001,
READY ?? = 6'b000_010,
WR_DataNew = 6'b000_100,
WR_AddrNew = 6'b001_000,
RD_DataNew = 6'b010_000,
RD_AddrNew = 6'b100_000,
?? WR ?? ?? = 1,
?? RD ??? = 0;

assign LED2_Flash = LED2_Flash_reg;
assign LED5_Flash = LED5_Flash_reg;
assign DMX_out1 = DMX_out1_reg;
assign _WE_OUT?? = _WE_OUT_reg;
assign _CE_OUT?? = _CE_OUT_reg;
assign _OE_OUT?? = _OE_OUT_reg;
assign DATA_INOUT = w_en? DATA_WRITE_BUFFER:8'bz;
assign DATA_READ_BUFFER = r_en? DATA_INOUT:8'bz;
assign Addr_OUT = Addr_OUT_reg;
initial
begin
?? state <= IDLE;
?? WR_RD_Return <= WR;
?? Addr_OUT_reg <= 16'b0000_0000_0000_0000;
end
/*******************************************************************
* description: use to creat 1Hz wave,
* ?? LED2 flashing to show the CPLD running
*******************************************************************/
always @ (posedge clk)
begin
?? if(LED2_Flash_1Hz_count == 3999999)
begin
?? LED2_Flash_1Hz_count <= 0;
?? LED2_Flash_reg_1Hz_buffer <= 1'b0;
end
else
begin
?? LED2_Flash_1Hz_count <= LED2_Flash_1Hz_count + 22'b0001;
?? LED2_Flash_reg_1Hz_buffer <= 1'b1;
end
end
/*****************************************************************
* LED2 Flashing
* thought LED2 to check the operate
******************************************************************/
always @ (posedge LED2_Flash_reg_1Hz_buffer)
begin
?? if (DATA_READ_BUFFER2 == 8'b0000_0001)
?? begin?? // if Write and read SROM OK, LED2 will flashing
if(LED2_Flash_reg == 1)
?? ??? LED2_Flash_reg <= 1'b0;
else
?? LED2_Flash_reg <= 1'b1;
?? end
?? else
??? LED2_Flash_reg <= 1'b1;
///*
?? if (key == 1'b0)
?? begin?? // here ,the key putdown ,LED5 flashing ,test LED5 hardware
if(LED5_Flash_reg == 1)
?? ??? LED5_Flash_reg <= 1'b0;
else
?? LED5_Flash_reg <= 1'b1;
?? end
?? else
??? LED5_Flash_reg <= 1'b1;
//*/
end
/*******************************************************************
*
*?? key , then push the key ,write one time and read one time
* SRAM IS63LV1024, to test SRAM operate
*
*********************************************************************/
always @(posedge clk)
begin
//使用狀態機的讀寫SRAM程序
case(state)
IDLE:
?? begin
?? _CE_OUT_reg <= 1'b0;
?? _OE_OUT_reg <= 1'b1;
?? _WE_OUT_reg <= 1'b1;
??? DATA_READ_BUFFER2 <= DATA_READ_BUFFER;
??? if(WR_RD_Return == WR)
?? ?? state <= WR_AddrNew;
??? else if(WR_RD_Return == RD)
?? state <= RD_AddrNew;
??? else
?? state <= 0;
?? end
READY:
?? ??? begin
?? ??? Addr_OUT_reg <= 16'b0000_0000_0000_0000;
?? DATA_WRITE_BUFFER?? <= 8'b0000_0000;
?? state <= IDLE;
?? end
WR_AddrNew:
?? begin
?? //Addr_OUT_reg <= Addr_OUT_reg + 16'b1;
??? //DATA_WRITE_BUFFER?? <= DATA_WRITE_BUFFER + 8'b1;
?? ??? Addr_OUT_reg <= 16'b0000_0000_0000_0001;
?? DATA_WRITE_BUFFER?? <= 8'b0000_0001;
?? state <= WR_DataNew;
?? end
WR_DataNew:
?? begin
??? _CE_OUT_reg <= 1'b0;
??? _WE_OUT_reg <= 1'b0;
??? _OE_OUT_reg <= 1'bz;
??? WR_RD_Return <= RD;
?? state <= IDLE;
?? end
RD_AddrNew:
?? begin
?? Addr_OUT_reg <= 16'b0000_0000_0000_0001;
???
?? state <= RD_DataNew;
?? end
RD_DataNew:
?? begin
??? _WE_OUT_reg <= 1'b1;
??? _CE_OUT_reg <= 1'b0;
??? _OE_OUT_reg <= 1'b0;
??? WR_RD_Return <= 1'bz;
??? state <= IDLE; ??
?? end??
endcase??
end
endmodule