k20test.v

只需要FPGA两个通用管脚

module TENBASET_TxD(clk20, Ethernet_TDp, Ethernet_TDm,inp,rdaddress);

// a 20MHz clock (this code won't work with a different frequency)
input clk20;

// the two differential 10BASE-T outputs
output Ethernet_TDp, Ethernet_TDm;
input [7:0] inp;
output [6:0] rdaddress;
// "IP source" - put an unused IP - if unsure, see comment below after the source code
parameter IPsource_1 = 0;//202;
parameter IPsource_2 = 0;//114;
parameter IPsource_3 = 0;//251;
parameter IPsource_4 = 0;//137;

// "IP destination" - put the IP of the PC you want to send to
parameter IPdestination_1 = 202;
parameter IPdestination_2 = 114;
parameter IPdestination_3 = 251;
parameter IPdestination_4 = 255;

// "Physical Address" - put the address of the PC you want to send to
parameter PhysicalAddress_1 = 8'h00;
parameter PhysicalAddress_2 = 8'h40;
parameter PhysicalAddress_3 = 8'hd0;
parameter PhysicalAddress_4 = 8'h91;
parameter PhysicalAddress_5 = 8'h76;
parameter PhysicalAddress_6 = 8'h75;

//////////////////////////////////////////////////////////////////////
// sends a packet roughly every second
reg [23:0] counter; always @(posedge clk20) counter<=counter+1;
reg StartSending; always @(posedge clk20) StartSending<=&counter;

//////////////////////////////////////////////////////////////////////
// we send a UDP packet, 18 bytes payload

// calculate the IP checksum, big-endian style
parameter IPchecksum1 = 32'h0000C53F + (IPsource_1<<8)+IPsource_2+(IPsource_3<<8)+IPsource_4+
                                                                (IPdestination_1<<8)+IPdestination_2+(IPdestination_3<<8)+(IPdestination_4);
parameter IPchecksum2 =  ((IPchecksum1&32'h0000FFFF)+(IPchecksum1>>16));
parameter IPchecksum3 = ~((IPchecksum2&32'h0000FFFF)+(IPchecksum2>>16));

reg [6:0] rdaddress;
reg [7:0] pkt_data;

always @(posedge clk20) 
case(rdaddress)
// Ethernet preamble
  7'h00: pkt_data <= inp;//8'h55;
  7'h01: pkt_data <= inp;//8'h55;
  7'h02: pkt_data <= inp;//8'h55;
  7'h03: pkt_data <= inp;//8'h55;
  7'h04: pkt_data <= inp;//8'h55;
  7'h05: pkt_data <= inp;//8'h55;
  7'h06: pkt_data <= inp;//8'h55;
  7'h07: pkt_data <= inp;//8'hD5;
// Ethernet header
  7'h08: pkt_data <= inp;//PhysicalAddress_1;
  7'h09: pkt_data <= inp;//PhysicalAddress_2;
  7'h0A: pkt_data <= inp;//PhysicalAddress_3;
  7'h0B: pkt_data <= inp;//PhysicalAddress_4;
  7'h0C: pkt_data <= inp;//PhysicalAddress_5;
  7'h0D: pkt_data <= inp;//PhysicalAddress_6;
  7'h0E: pkt_data <= inp;//8'h00;
  7'h0F: pkt_data <= inp;//8'h12;
  7'h10: pkt_data <= inp;//8'h34;
  7'h11: pkt_data <= inp;//8'h56;
  7'h12: pkt_data <= inp;//8'h78;
  7'h13: pkt_data <= inp;//8'h90;
// IP header
  7'h14: pkt_data <= inp;//8'h08;
  7'h15: pkt_data <= inp;//8'h00;
 //上层数据类型    0x0800：IP协议数据；0x809B：AppleTalk协议数据；
  7'h16: pkt_data <= inp;//8'h45;//长度不包括0x0800
//1、Version＝4，表示IP协议的版本号为4。该部分占4个BIT位。 
//2、Header Length=20 Bytes，表示IP包头的总长度为20个字节。
//该部分占4个BIT位，单位为4个字节，因此，一个IP包头的长度最长为“1111”，即15＊4＝60个字节。
  7'h17: pkt_data <= inp;//8'h00;
//3、Type of Service=00，表示服务类型为0。该部分用二个十六进制值来表示，共占8个BIT。 
//8个BIT的含义是： 
//000 前三位不用 
//0 表示最小时延，如Telnet服务使用该位 
//0 表示吞吐量，如FTP服务使用该位 
//0 表示可靠性，如SNMP服务使用该位 
//0 表示最小代价 
//0 不用
  7'h18: pkt_data <= inp;//8'h00;
  7'h19: pkt_data <= inp;//8'h2E;//0x2e->46
//Total Length=48Bytes,表示该IP包的总长度为48个字节。该部分占16个BIT，单位为Byte。
//由此IP数据包的最大长度为2的16次方减1，即：65535个字节。
//因此，在以太网中能够传输的最大IP数据包为65535个字节。 
  7'h1A: pkt_data <= inp;//8'h00;
  7'h1B: pkt_data <= inp;//8'h00;
//Identification=363，表示IP包识别号为363。该部分占16个BIT，以十进制数表示。[程序当中没有这个东西]
  7'h1C: pkt_data <= inp;//8'h00;
  7'h1D: pkt_data <= inp;//8'h00;
//Flags，表示片标志，占3个BIT。各位含义分别为：第一个“0”不用，第二个“0”为分片标志位，“1”表示分片，“0”表示不分版本。
//第三个0为是否最后一片标志位，0表示最后一片，1表示还有更多的片。 
//Fragment Offset＝0，表示片偏移为0个Bytes。该部分占13个BIT。
  7'h1E: pkt_data <= inp;//8'h80;
//Time to Live=128Secongs/Hops，表示生存时间TTL值为128.该部分占8个BIT
//当IP包通过一个路由器时，TTL就会减一，当TTL为0时，此IP包将被直接丢弃
  7'h1F: pkt_data <= inp;//8'h11;
//Proctol＝6（TCP），表示协议类型为TCP，协议代码是6.如果是UDP协议，则此处的协议代码应为17.
//如果是ICMP协议，则此处的协议代码应为1.该部分占8个BIT.
//1：ICMP；2：IGMP；3：GGP；4：IP；6：TCP；8：EGP；17：UDP
  7'h20: pkt_data <= inp;//IPchecksum3[15:8];
  7'h21: pkt_data <= inp;//IPchecksum3[ 7:0];
  7'h22: pkt_data <= inp;//IPsource_1;
  7'h23: pkt_data <= inp;//IPsource_2;
  7'h24: pkt_data <= inp;//IPsource_3;
  7'h25: pkt_data <= inp;//IPsource_4;
  7'h26: pkt_data <= inp;//IPdestination_1;
  7'h27: pkt_data <= inp;//IPdestination_2;
  7'h28: pkt_data <= inp;//IPdestination_3;
  7'h29: pkt_data <= inp;//IPdestination_4;//上面说的长度20是到这里
// UDP header
  7'h2A: pkt_data <= inp;//8'h04;
  7'h2B: pkt_data <= inp;//8'h00;
//source port
  7'h2C: pkt_data <= inp;//8'h04;
  7'h2D: pkt_data <= inp;//8'h00;
//destination port
  7'h2E: pkt_data <= inp;//8'h00;
  7'h2F: pkt_data <= inp;//8'h1A;
  7'h30: pkt_data <= inp;//8'h00;
  7'h31: pkt_data <= inp;//8'h00;
// payload
  7'h32: pkt_data <= inp; // put here the data that you want to send
  7'h33: pkt_data <= inp; // put here the data that you want to send
  7'h34: pkt_data <= inp; // put here the data that you want to send
  7'h35: pkt_data <= inp; // put here the data that you want to send
  7'h36: pkt_data <= inp; // put here the data that you want to send
  7'h37: pkt_data <= inp; // put here the data that you want to send
  7'h38: pkt_data <= inp; // put here the data that you want to send
  7'h39: pkt_data <= inp; // put here the data that you want to send
  7'h3A: pkt_data <= inp; // put here the data that you want to send
  7'h3B: pkt_data <= inp; // put here the data that you want to send
  7'h3C: pkt_data <= inp; // put here the data that you want to send
  7'h3D: pkt_data <= inp; // put here the data that you want to send
  7'h3E: pkt_data <= inp; // put here the data that you want to send
  7'h3F: pkt_data <= inp; // put here the data that you want to send
  7'h40: pkt_data <= inp; // put here the data that you want to send
  7'h41: pkt_data <= inp; // put here the data that you want to send
  7'h42: pkt_data <= inp; // put here the data that you want to send
  7'h43: pkt_data <= inp; // put here the data that you want to send
  default: pkt_data <= 8'h00;
endcase

//////////////////////////////////////////////////////////////////////
// and finally the 10BASE-T's magic
reg [3:0] ShiftCount;
reg SendingPacket;
always @(posedge clk20) if(StartSending) SendingPacket<=1; else if(ShiftCount==14 && rdaddress==7'h48) SendingPacket<=0;
always @(posedge clk20) ShiftCount <= SendingPacket ? ShiftCount+1 : 15;
wire readram = (ShiftCount==15);
always @(posedge clk20) if(ShiftCount==15) rdaddress <= SendingPacket ? rdaddress+1 : 0;
reg [7:0] ShiftData; always @(posedge clk20) if(ShiftCount[0]) ShiftData <= readram ? pkt_data : {1'b0, ShiftData[7:1]};

// generate the CRC32
reg [31:0] CRC;
reg CRCflush; always @(posedge clk20) if(CRCflush) CRCflush <= SendingPacket; else if(readram) CRCflush <= (rdaddress==7'h44);
reg CRCinit; always @(posedge clk20) if(readram) CRCinit <= (rdaddress==7);
wire CRCinput = CRCflush ? 0 : (ShiftData[0] ^ CRC[31]);
always @(posedge clk20) if(ShiftCount[0]) CRC <= CRCinit ? ~0 : ({CRC[30:0],1'b0} ^ ({32{CRCinput}} & 32'h04C11DB7));

// generate the NLP	--OK
reg [17:0] LinkPulseCount; always @(posedge clk20) LinkPulseCount <= SendingPacket ? 0 : LinkPulseCount+1;
reg LinkPulse; always @(posedge clk20) LinkPulse <= &LinkPulseCount[17:1];

// TP_IDL, shift-register and manchester encoder
reg SendingPacketData; always @(posedge clk20) SendingPacketData <= SendingPacket;
reg [2:0] idlecount; always @(posedge clk20) if(SendingPacketData) idlecount<=0; else if(~&idlecount) idlecount<=idlecount+1;
wire dataout = CRCflush ? ~CRC[31] : ShiftData[0];
reg qo; always @(posedge clk20) qo <= SendingPacketData ? ~dataout^ShiftCount[0] : 1;
reg qoe; always @(posedge clk20) qoe <= SendingPacketData | LinkPulse | (idlecount<6);
reg Ethernet_TDp; always @(posedge clk20) Ethernet_TDp <= (qoe ? qo : 1'b0);
reg Ethernet_TDm; always @(posedge clk20) Ethernet_TDm <= (qoe ? ~qo : 1'b0);

endmodule