/*	author: liutong	data: 2008.12.05	univerisal function:			$如果start輸入為假，則也會在這一字節數據并串轉換完后才結束；			$上升沿發送數據；	unique function:			$接收d[7:0]輸入的數據，并發送出去；*/module _232_txd_t1(reset,clk,start,	sdout,busy);input reset,clk,start;output sdout,busy;reg sdout;reg busy;reg [7:0] data_in;reg [3:0] count;reg [1:0]prg;reg [8:0]txd_counter;  always @(posedge clk or negedge reset)  begin    if(!reset)    begin		data_in<=8'd1;		prg	<=2'b00;		count<=4'b0;		sdout<=1'bz;		busy<=1'b0;		txd_counter<=9'd1;	 end    else if((start==1)/*&&(txd_counter<=300)*/)	case (prg)		2'b00:		begin				prg<=2'b01;				busy<=1;			sdout<=1'b0;	    end		2'b01:		begin			if(count==7) 	prg<=2'b11;			else prg<=2'b01;			///==============================================			sdout<=data_in[0];			data_in[7:0]<={1'b0,data_in[7:1]};			count<=count+4'd1;		end		2'b11:		begin			sdout<=1'b1;			prg<=2'b10;			txd_counter<=txd_counter+9'd1;		end			2'b10:		begin			data_in[7:0]<=txd_counter[7:0];				count<=4'd0; 			prg<=2'b00;		end	endcase	else	begin		data_in<=8'd1;
		prg	<=2'b00;
		count<=4'b0;
		sdout<=1'bz;
		busy<=1'b0;	 end  endendmodule