_232_txd_t1.v

多功能卡的源代码

 /*
	author: liutong
	data: 2008.12.05
	univerisal function:
			$如果start输入为假，则也会在这一字节数据并串转换完后才结束；
			$上升沿发送数据；
	unique function:
			$接收d[7:0]输入的数据，并发送出去；
*/
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
  end
endmodule