Ethernet.v

   1 `define ADDR_ETH_STATUS 16'hFF68
   2 `define ADDR_ETH 16'hFF69
   3
   4 module Ethernet (
   5         input clk,
   6         input wr,
   7         input rd,
   8         input [15:0] addr,
   9         inout [7:0] data,
  10         input ethclk, rxclk,
  11         input rxp, rxm,
  12         output txp, txm);
  13
  14         wire [10:0] txhwaddr;
  15         wire [7:0] txhwdata;
  16         wire txbusy;
  17
  18         reg [10:0] txlength = 0;
  19         reg [10:0] txwraddr = 0;
  20         reg [1:0] txstate = 0;
  21         reg txstart = 0;
  22
  23         reg [15:0] addrlatch;
  24         reg rdlatch;
  25
  26         wire decode = (addrlatch == `ADDR_ETH_STATUS) || (addrlatch == `ADDR_ETH);
  27         reg [7:0] odata;
  28         assign data = (decode && rdlatch) ? odata : 8'bzzzzzzzz;
  29
  30         EnetTX tx(
  31                 .clk20(ethclk),
  32                 .Ethernet_TDp(txp),
  33                 .Ethernet_TDm(txm),
  34                 .busy(txbusy),
  35                 .length(txlength),
  36                 .rdaddress(txhwaddr),
  37                 .start(txstart),
  38                 .indata(txhwdata));
  39
  40         EthModRam txram(
  41                 .wdata(data),
  42                 .waddr(txwraddr),
  43                 .wr(wr && txstate == 2'b10 && addr == `ADDR_ETH),
  44                 .wrclk(clk),
  45                 .rdata(txhwdata),
  46                 .raddr(txhwaddr),
  47                 .rdclk(ethclk));
  48
  49         wire [10:0] rxphyaddr;
  50         wire [7:0] rxphydata;
  51         wire rxphywr;
  52         wire rxpktrdy;
  53         reg rxclear = 0;
  54         reg [1:0] rxstate = 0;
  55         wire [10:0] rxlength;
  56         reg [10:0] rxcurlength;
  57
  58         reg [10:0] rxcoreaddr = 0;
  59         wire [7:0] rxcoredata;
  60
  61         EnetRX rx(
  62                 .rxclk(rxclk),
  63                 .manchester_data_in(~rxp),
  64                 .wr(rxphywr),
  65                 .oaddr(rxphyaddr),
  66                 .odata(rxphydata),
  67                 .pktrdy(rxpktrdy),
  68                 .olength(rxlength),
  69                 .pktclear(rxclear));
  70
  71         EthModRam rxram(
  72                 .wdata(rxphydata),
  73                 .waddr(rxphyaddr),
  74                 .wr(rxphywr),
  75                 .wrclk(rxclk),
  76                 .rdata(rxcoredata),
  77                 .raddr(rxcoreaddr),
  78                 .rdclk(clk));
  79
  80         always @ (posedge clk) begin
  81                 addrlatch <= addr;
  82                 rdlatch <= rd;
  83
  84                 if (rd && addr == `ADDR_ETH_STATUS)
  85                         odata <= {txstate,4'b0,rxpktrdy,txbusy};
  86                 else if (wr && addr == `ADDR_ETH_STATUS) begin          /* Reset the state machines. */
  87                         rxstate <= 2'b00;
  88                         txstate <= 2'b00;
  89                 end else if (rd && addr == `ADDR_ETH) begin
  90                         case (rxstate)
  91                         2'b00: begin
  92                                 if (!rxpktrdy)
  93                                         rxcurlength <= 0;
  94                                 else
  95                                         rxcurlength <= rxlength;
  96                                 odata <= rxpktrdy ? {5'b0,rxlength[10:8]} : 8'b0;
  97                                 rxstate <= 2'b01;
  98                         end
  99                         2'b01: begin
 100                                 rxstate <= (rxcurlength == 0) ? 2'b00 : 2'b10;
 101                                 odata <= rxcurlength[7:0];
 102                                 rxcoreaddr <= 0;
 103                         end
 104                         2'b10: begin
 105                                 odata <= rxcoredata;
 106                                 if (rxcoreaddr == (rxcurlength - 1)) begin
 107                                         rxstate <= 2'b11;
 108                                         rxclear <= 1;
 109                                 end else
 110                                         rxcoreaddr <= rxcoreaddr + 1;
 111                         end
 112                         endcase
 113                 end else if (rxstate == 2'b11 || rxclear) begin
 114                         rxstate <= 2'b00;
 115                         rxclear <= 0;
 116                 end else if (wr && addr == `ADDR_ETH) begin
 117                         case(txstate)
 118                         2'b00: begin
 119                                 txlength[10:8] <= data[2:0];
 120                                 txstate <= 2'b01;
 121                         end
 122                         2'b01: begin
 123                                 txlength[7:0] <= data[7:0];
 124                                 txstate <= 2'b10;
 125                                 txwraddr <= 0;
 126                         end
 127                         2'b10:
 128                                 if(txwraddr == (txlength - 1)) begin
 129                                         txstate <= 2'b11;
 130                                         txstart <= 1'b1;
 131                                 end else
 132                                         txwraddr <= txwraddr + 1;
 133                         endcase
 134                 end else if (txstate == 2'b11) begin
 135                         txstart <= 1'b0;
 136                         txstate <= 2'b00;
 137                 end
 138         end
 139
 140 endmodule
 141
 142 module EthModRam (
 143         input [7:0] wdata,
 144         input [10:0] waddr,
 145         input [10:0] raddr,
 146         input wr,
 147         input wrclk,
 148         input rdclk,
 149         output reg [7:0] rdata);
 150
 151         reg [7:0] mem [1600:0];
 152
 153         always @(posedge wrclk) begin
 154                 if(wr)
 155                         mem[waddr] <= wdata;
 156         end
 157
 158         always @(posedge rdclk)
 159                 rdata <= mem[raddr];
 160 endmodule
 161
 162 module EnetTX(input clk20, output reg Ethernet_TDp, output reg Ethernet_TDm, output wire busy, input start, input [11:0] length, output wire [11:0] rdaddress, input [7:0] indata);
 163         reg StartSending; always @(posedge clk20) StartSending<=start;
 164         reg [11:0] curlen = 0; always @(posedge clk20) if (start) curlen <= length + 8;
 165
 166         reg [11:0] internaladdr;
 167         assign rdaddress = internaladdr - 8;
 168         wire [7:0] pkt_data = (internaladdr < 7) ? 8'h55 :
 169                                 (internaladdr == 7) ? 8'hD5 :
 170                                 indata;
 171
 172         //////////////////////////////////////////////////////////////////////
 173         // and finally the 10BASE-T's magic
 174         reg [3:0] ShiftCount;
 175         reg SendingPacket;
 176         always @(posedge clk20) if(StartSending) SendingPacket<=1; else if(ShiftCount==14 && internaladdr==(curlen + 4)) SendingPacket<=0;
 177         always @(posedge clk20) ShiftCount <= SendingPacket ? ShiftCount+1 : 15;
 178         wire readram = (ShiftCount==15);
 179         always @(posedge clk20) if(ShiftCount==15) internaladdr <= SendingPacket ? internaladdr+1 : 0;
 180         reg [7:0] ShiftData; always @(posedge clk20) if(ShiftCount[0]) ShiftData <= readram ? pkt_data : {1'b0, ShiftData[7:1]};
 181
 182         // generate the CRC32
 183         reg [31:0] CRC;
 184         reg CRCflush; always @(posedge clk20) if(CRCflush) CRCflush <= SendingPacket; else if(readram) CRCflush <= (internaladdr==curlen);
 185         reg CRCinit; always @(posedge clk20) if(readram) CRCinit <= (internaladdr==7);
 186         wire CRCinput = CRCflush ? 0 : (ShiftData[0] ^ CRC[31]);
 187         always @(posedge clk20) if(ShiftCount[0]) CRC <= CRCinit ? ~0 : ({CRC[30:0],1'b0} ^ ({32{CRCinput}} & 32'h04C11DB7));
 188
 189         // generate the NLP
 190         reg [17:0] LinkPulseCount; always @(posedge clk20) LinkPulseCount <= SendingPacket ? 0 : LinkPulseCount+1;
 191         reg LinkPulse; always @(posedge clk20) LinkPulse <= &LinkPulseCount[17:1];
 192
 193         // TP_IDL, shift-register and manchester encoder
 194         reg SendingPacketData; always @(posedge clk20) SendingPacketData <= SendingPacket;
 195         assign busy = SendingPacketData;
 196         reg [2:0] idlecount; always @(posedge clk20) if(SendingPacketData) idlecount<=0; else if(~&idlecount) idlecount<=idlecount+1;
 197         wire dataout = CRCflush ? ~CRC[31] : ShiftData[0];
 198         reg qo; always @(posedge clk20) qo <= SendingPacketData ? ~dataout^ShiftCount[0] : 1;
 199         reg qoe; always @(posedge clk20) qoe <= SendingPacketData | LinkPulse | (idlecount<6);
 200         always @(posedge clk20) Ethernet_TDp <= (qoe ? qo : 1'b0);
 201         always @(posedge clk20) Ethernet_TDm <= (qoe ? ~qo : 1'b0);
 202 endmodule
 203
 204 module EnetRX(
 205         input rxclk,
 206         input manchester_data_in,
 207         output reg wr,
 208         output reg [10:0] oaddr,
 209         output reg [7:0] odata,
 210         output reg pktrdy = 0,
 211         output reg [10:0] olength = 0,
 212         input pktclear);
 213
 214         reg [2:0] in_data;
 215         always @(posedge rxclk) in_data <= {in_data[1:0], manchester_data_in};
 216
 217         reg [7:0] data;
 218
 219         reg [1:0] cnt;
 220         always @(posedge rxclk) if(|cnt || (in_data[2] ^ in_data[1])) cnt<=cnt+1;
 221
 222         reg new_bit_avail;
 223         always @(posedge rxclk) new_bit_avail <= (cnt==3);
 224         always @(posedge rxclk) if(cnt==3) data<={in_data[1],data[7:1]};
 225
 226         /////////////////////////////////////////////////
 227         reg end_of_Ethernet_frame;
 228
 229         reg [4:0] sync1;
 230         always @(posedge rxclk)
 231                 if(end_of_Ethernet_frame)
 232                         sync1<=0;
 233                 else if(new_bit_avail) begin
 234                         if(!(data==8'h55 || data==8'hAA))       // not preamble?
 235                                 sync1 <= 0;
 236                         else
 237                                 if(~&sync1)             // if all bits of this "sync1" counter are one, we decide that enough of the preamble
 238                                                         // has been received, so stop counting and wait for "sync2" to detect the SFD
 239                                         sync1 <= sync1 + 1; // otherwise keep counting
 240                 end
 241
 242         reg [9:0] sync2;
 243         always @(posedge rxclk)
 244                 if(end_of_Ethernet_frame || pktrdy)     // i.e., if we're busy, drop it on the floor
 245                         sync2 <= 0;
 246                 else
 247                 if(new_bit_avail) begin
 248                         if(|sync2) // if the SFD has already been detected (Ethernet data is coming in)
 249                                 sync2 <= sync2 + 1; // then count the bits coming in
 250                         else if(&sync1 && data==8'hD5) // otherwise, let's wait for the SFD (0xD5)
 251                                 sync2 <= sync2 + 1;
 252                 end
 253
 254         wire new_byte_available = new_bit_avail && (sync2[2:0]==3'h0) && (sync2[9:3]!=0);
 255
 256         /////////////////////////////////////////////////
 257         // if no clock transistion is detected for some time, that's the end of the Ethernet frame
 258
 259         reg [2:0] transition_timeout;
 260         always @(posedge rxclk) if(in_data[2]^in_data[1]) transition_timeout<=0; else if(~&cnt) transition_timeout<=transition_timeout+1;
 261         always @(posedge rxclk) end_of_Ethernet_frame <= &transition_timeout;
 262         reg [11:0] iaddr;
 263
 264         /////////////////////////////////////////////////
 265         always @(posedge rxclk)
 266                 if (new_byte_available && !pktrdy) begin
 267                         odata <= data;
 268                         oaddr <= iaddr;
 269                         iaddr <= iaddr + 1;
 270                         wr <= 1;
 271                 end else if (end_of_Ethernet_frame && (iaddr > 1)) begin
 272                         olength <= iaddr;
 273                         iaddr <= 0;
 274                         wr <= 0;
 275                         pktrdy <= 1;
 276                 end else if (pktclear) begin
 277                         pktrdy <= 0;
 278                         wr <= 0;
 279                 end else
 280                         wr <= 0;
 281
 282 endmodule