Moved usrp2 fpga files into usrp2 subdir.

6 files changed, 955 insertions, 0 deletions

diff --git a/usrp2/serdes/serdes.v b/usrp2/serdes/serdes.v
new file mode 100644
index 000000000..17049bfe6
--- /dev/null
+++ b/usrp2/serdes/serdes.v
@@ -0,0 +1,63 @@
+
+// SERDES TX and RX along with all flow control logic
+
+module serdes
+  #(parameter TXFIFOSIZE = 9,
+    parameter RXFIFOSIZE = 9)
+    (input clk, input rst,
+     // TX side
+     output ser_tx_clk, output [15:0] ser_t, output ser_tklsb, output ser_tkmsb,
+     input [31:0] rd_dat_i, input [3:0] rd_flags_i, output rd_ready_o, input rd_ready_i,
+     // RX side
+     input ser_rx_clk, input [15:0] ser_r, input ser_rklsb, input ser_rkmsb,
+     output [31:0] wr_dat_o, output [3:0] wr_flags_o, output wr_ready_o, input wr_ready_i,
+
+     output [15:0] tx_occupied, output tx_full, output tx_empty,
+     output [15:0] rx_occupied, output rx_full, output rx_empty,
+
+     output serdes_link_up,
+     
+     output [31:0] debug0, 
+     output [31:0] debug1);
+
+   wire [15:0] fifo_space;
+   wire        xon_rcvd, xoff_rcvd, inhibit_tx, send_xon, send_xoff, sent;
+   wire [31:0] debug_rx, debug_tx;
+
+   serdes_tx #(.FIFOSIZE(TXFIFOSIZE)) serdes_tx
+     (.clk(clk),.rst(rst),
+      .ser_tx_clk(ser_tx_clk),.ser_t(ser_t),.ser_tklsb(ser_tklsb),.ser_tkmsb(ser_tkmsb),
+      .rd_dat_i(rd_dat_i),.rd_flags_i(rd_flags_i),.rd_ready_o(rd_ready_o),.rd_ready_i(rd_ready_i),
+      .inhibit_tx(inhibit_tx), .send_xon(send_xon), .send_xoff(send_xoff), .sent(sent),
+      .fifo_occupied(tx_occupied),.fifo_full(tx_full),.fifo_empty(tx_empty),
+      .debug(debug_tx) );
+   
+   serdes_rx #(.FIFOSIZE(RXFIFOSIZE)) serdes_rx
+     (.clk(clk),.rst(rst),
+      .ser_rx_clk(ser_rx_clk),.ser_r(ser_r),.ser_rklsb(ser_rklsb),.ser_rkmsb(ser_rkmsb),
+      .wr_dat_o(wr_dat_o),.wr_flags_o(wr_flags_o),.wr_ready_o(wr_ready_o),.wr_ready_i(wr_ready_i),
+      .fifo_space(fifo_space), .xon_rcvd(xon_rcvd), .xoff_rcvd(xoff_rcvd),
+      .fifo_occupied(rx_occupied),.fifo_full(rx_full),.fifo_empty(rx_empty),
+      .serdes_link_up(serdes_link_up), .debug(debug_rx) );
+
+   serdes_fc_tx serdes_fc_tx
+     (.clk(clk),.rst(rst),
+      .xon_rcvd(xon_rcvd),.xoff_rcvd(xoff_rcvd),.inhibit_tx(inhibit_tx) );
+
+   serdes_fc_rx #(.LWMARK(32),.HWMARK(128)) serdes_fc_rx
+     (.clk(clk),.rst(rst),
+      .fifo_space(fifo_space),.send_xon(send_xon),.send_xoff(send_xoff),.sent(sent) );
+
+   //assign      debug = { fifo_space, send_xon, send_xoff, debug_rx[13:0] };
+   //assign      debug = debug_rx;
+
+   assign      debug0 = { { 2'b00, rd_ready_o, rd_ready_i, rd_flags_i[3:0]},
+			  { debug_tx[5:4] /* full,empty */ , inhibit_tx, send_xon, send_xoff, sent, ser_tkmsb, ser_tklsb},
+			  { ser_t[15:8] },
+			  { ser_t[7:0] } };
+   
+   assign      debug1 = { { debug_rx[7:0] }, /*  odd,xfer_active,sop_i,eop_i,error_i,state[2:0] */
+			  { wr_flags_o[1:0], wr_ready_i, wr_ready_o,  xon_rcvd, xoff_rcvd, ser_rkmsb, ser_rklsb },
+			  { ser_r[15:8] },
+			  { ser_r[7:0] } };
+endmodule // serdes
diff --git a/usrp2/serdes/serdes_fc_rx.v b/usrp2/serdes/serdes_fc_rx.v
new file mode 100644
index 000000000..4dd46e27f
--- /dev/null
+++ b/usrp2/serdes/serdes_fc_rx.v
@@ -0,0 +1,62 @@
+
+
+module serdes_fc_rx
+  #(parameter LWMARK = 64,
+    parameter HWMARK = 320)
+    (input clk, input rst,
+     input [15:0] fifo_space, 
+     output reg send_xon,
+     output reg send_xoff,
+     input sent);
+    
+   reg [15:0] 	  countdown;
+   reg 		  send_xon_int, send_xoff_int;
+   
+   always @(posedge clk)
+     if(rst)
+       begin
+	  send_xon_int <= 0;
+	  send_xoff_int <= 0;
+	  countdown <= 0;
+       end
+     else 
+       begin
+	  send_xon_int <= 0;
+	  send_xoff_int <= 0;
+	  if(countdown == 0)
+	    if(fifo_space < LWMARK)
+	      begin
+		 send_xoff_int <= 1;
+		 countdown <= 240;
+	      end
+	    else
+	      ;
+	  else
+	    if(fifo_space > HWMARK)
+	      begin
+		 send_xon_int <= 1;
+		 countdown <= 0;
+	      end
+	    else
+	      countdown <= countdown - 1;
+       end // else: !if(rst)
+
+   // If we are between the high and low water marks, we let the countdown expire
+
+   always @(posedge clk)
+     if(rst)
+       send_xon <= 0;
+     else if(send_xon_int)
+       send_xon <= 1;
+     else if(sent)
+       send_xon <= 0;
+
+   always @(posedge clk)
+     if(rst)
+       send_xoff <= 0;
+     else if(send_xoff_int)
+       send_xoff <= 1;
+     else if(sent)
+       send_xoff <= 0;
+   
+endmodule // serdes_fc_rx
diff --git a/usrp2/serdes/serdes_fc_tx.v b/usrp2/serdes/serdes_fc_tx.v
new file mode 100644
index 000000000..2fe967c8d
--- /dev/null
+++ b/usrp2/serdes/serdes_fc_tx.v
@@ -0,0 +1,24 @@
+
+
+module serdes_fc_tx
+  (input clk, input rst,
+   input xon_rcvd, input xoff_rcvd, output reg inhibit_tx);
+
+   // XOFF means stop sending, XON means start sending
+   // clock domain stuff happens elsewhere, everything here is on main clk
+
+   reg [15:0] state;
+   always @(posedge clk)
+     if(rst)
+       state <= 0;
+     else if(xoff_rcvd)
+       state <= 255;
+     else if(xon_rcvd)
+       state <= 0;
+     else if(state !=0)
+       state <= state - 1;
+
+   always @(posedge clk)
+     inhibit_tx <= (state != 0);
+   
+endmodule // serdes_fc_tx
diff --git a/usrp2/serdes/serdes_rx.v b/usrp2/serdes/serdes_rx.v
new file mode 100644
index 000000000..afefccaa1
--- /dev/null
+++ b/usrp2/serdes/serdes_rx.v
@@ -0,0 +1,292 @@
+
+// SERDES Interface
+
+// LS-Byte is sent first, MS-Byte is second
+// Invalid K Codes
+//  K0.0  000-00000  Error detected
+//  K31.7 111-11111  Loss of input signal
+
+// Valid K Codes
+//  K28.0 000-11100
+//  K28.1 001-11100  Alternate COMMA?
+//  K28.2 010-11100
+//  K28.3 011-11100
+//  K28.4 100-11100
+//  K28.5 101-11100  Standard COMMA?
+//  K28.6 110-11100
+//  K28.7 111-11100  Bad COMMA?
+//  K23.7 111-10111
+//  K27.7 111-11011
+//  K29.7 111-11101
+//  K30.7 111-11110
+
+module serdes_rx
+  #(parameter FIFOSIZE = 9)
+    (input clk,
+     input rst,
+     
+     // RX HW Interface
+     input ser_rx_clk,
+     input [15:0] ser_r,
+     input ser_rklsb,
+     input ser_rkmsb,
+     
+     output [31:0] wr_dat_o,
+     output [3:0] wr_flags_o,
+     input wr_ready_i,
+     output wr_ready_o,
+     
+     output [15:0] fifo_space,
+     output xon_rcvd, output xoff_rcvd,
+
+     output [15:0] fifo_occupied, output fifo_full, output fifo_empty,
+     output reg serdes_link_up,
+     output [31:0] debug
+     );
+
+   localparam K_COMMA = 8'b101_11100;     // 0xBC K28.5
+   localparam K_IDLE = 8'b001_11100;      // 0x3C K28.1
+   localparam K_PKT_START = 8'b110_11100; // 0xDC K28.6
+   localparam K_PKT_END = 8'b100_11100;   // 0x9C K28.4
+   localparam K_XON = 8'b010_11100;       // 0x5C K28.2
+   localparam K_XOFF = 8'b011_11100;      // 0x7C K28.3
+   localparam K_LOS = 8'b111_11111;       // 0xFF K31.7
+   localparam K_ERROR = 8'b000_00000;     // 0x00 K00.0
+   localparam D_56 = 8'b110_00101;        // 0xC5 D05.6
+   
+   localparam IDLE = 3'd0;
+   localparam FIRSTLINE1 = 3'd1;
+   localparam FIRSTLINE2 = 3'd2;
+   localparam PKT1 = 3'd3;
+   localparam PKT2 = 3'd4;
+   localparam CRC_CHECK = 3'd5;
+   localparam ERROR = 3'd6;
+   localparam DONE = 3'd7;
+   
+   wire [17:0] even_data;
+   reg [17:0]  odd_data;
+   wire [17:0] chosen_data;
+   reg 	       odd;
+   
+   reg [31:0]  line_i;
+   reg 	       sop_i, eop_i, error_i;
+   wire        error_o, sop_o, eop_o, write;
+   reg [15:0]  halfline;
+   reg [8:0]   holder;
+   wire [31:0] line_o;
+   
+   reg [2:0]   state;
+
+   reg [15:0]  CRC;
+   wire [15:0] nextCRC;
+   reg 	       write_d;
+
+   wire        rst_rxclk;
+   wire        have_space;
+
+   oneshot_2clk rst_1s(.clk_in(clk),.in(rst),.clk_out(ser_rx_clk),.out(rst_rxclk));
+
+   assign      even_data = {ser_rkmsb,ser_rklsb,ser_r};
+   
+   always @(posedge ser_rx_clk)
+     if(rst_rxclk)
+       holder <= 9'd0;
+     else
+       holder <= {even_data[17],even_data[15:8]};
+   
+   always @(posedge ser_rx_clk)
+     if(rst_rxclk)
+       odd_data <= 18'd0;
+     else
+       odd_data <= {even_data[16],holder[8],even_data[7:0],holder[7:0]};
+   
+   assign      chosen_data = odd ? odd_data : even_data;
+
+   // Transfer xon and xoff info to the main system clock for flow control purposes
+   reg 	       xon_rcvd_rxclk, xoff_rcvd_rxclk;
+   always @(posedge ser_rx_clk)
+     xon_rcvd_rxclk = ({1'b1,K_XON} == {ser_rkmsb,ser_r[15:8]}) | ({1'b1,K_XON} == {ser_rklsb,ser_r[7:0]} );
+   always @(posedge ser_rx_clk)
+     xoff_rcvd_rxclk = ({1'b1,K_XOFF} == {ser_rkmsb,ser_r[15:8]}) | ({1'b1,K_XOFF} == {ser_rklsb,ser_r[7:0]} );
+   
+   oneshot_2clk xon_1s(.clk_in(ser_rx_clk),.in(xon_rcvd_rxclk),.clk_out(clk),.out(xon_rcvd));
+   oneshot_2clk xoff_1s(.clk_in(ser_rx_clk),.in(xoff_rcvd_rxclk),.clk_out(clk),.out(xoff_rcvd));
+
+   // If the other side is sending xon or xoff, or is flow controlled (b/c we told them to be), don't fill the fifos
+   wire        wait_here = ((chosen_data == {2'b10,K_COMMA,D_56})||
+			    (chosen_data == {2'b11,K_XON,K_XON})||
+			    (chosen_data == {2'b11,K_XOFF,K_XOFF}) );
+
+   always @(posedge ser_rx_clk)
+     if(rst_rxclk) sop_i <= 0;
+     else if(state == FIRSTLINE1) sop_i <= 1;
+     else if(write_d) sop_i <= 0;
+   
+   reg 	       write_pre;
+   always @(posedge ser_rx_clk)
+     if(rst_rxclk)
+       begin
+	  state <= IDLE;
+	  odd <= 0;
+	  halfline <= 0;
+	  line_i <= 0;
+	  eop_i <= 0;
+	  error_i <= 0;
+	  write_pre <= 0;
+       end
+     else
+       case(state)
+	 IDLE :
+	   begin
+	      error_i <= 0;
+	      write_pre <= 0;
+	      if(even_data == {2'b11,K_PKT_START,K_PKT_START})
+		begin
+		   state <= FIRSTLINE1;
+		   odd <= 0;
+		end
+	      else if(odd_data == {2'b11,K_PKT_START,K_PKT_START})
+		begin
+		   state <= FIRSTLINE1;
+		   odd <= 1;
+		end
+	   end
+
+	 FIRSTLINE1 :
+	   if(chosen_data[17:16] == 0)
+	     begin
+		halfline <= chosen_data[15:0];
+		state <= FIRSTLINE2;
+	     end
+	   else if(wait_here)
+	     ;  // Flow Controlled, so wait here and do nothing
+	   else
+	     state <= ERROR;
+
+	 FIRSTLINE2 :
+	   if(chosen_data[17:16] == 0)
+	     begin
+		line_i <= {chosen_data[15:0],halfline};
+		if(~have_space)  // No space to write to!  Should have been avoided by flow control
+		  state <= ERROR;
+		else
+		  begin
+		     state <= PKT1;
+		     write_pre <= 1;
+		  end
+	     end // if (chosen_data[17:16] == 0)
+	   else if(wait_here)
+	     ;  // Flow Controlled, so wait here and do nothing
+	   else
+	     state <= ERROR;
+	 
+	 PKT1 :
+	   begin
+	      write_pre <= 0;
+	      if(chosen_data[17:16] == 0)
+		begin
+		   halfline <= chosen_data[15:0];
+		   state <= PKT2;
+		end
+	      else if(wait_here)
+		;  // Flow Controlled
+	      else if(chosen_data == {2'b11,K_PKT_END,K_PKT_END})
+	  	state <= CRC_CHECK;
+	      else
+		state <= ERROR;
+	   end // case: PKT1
+	 
+	 PKT2 :
+	   if(chosen_data[17:16] == 0)
+	     begin
+		line_i <= {1'b0,1'b0,1'b0,chosen_data[15:0],halfline};
+		if(~have_space)  // No space to write to!
+		  state <= ERROR;
+		else
+		  begin
+		     state <= PKT1;
+		     write_pre <= 1;
+		  end
+	     end // if (chosen_data[17:16] == 0)
+	   else if(wait_here)
+	     ;  // Flow Controlled
+	   else
+	     state <= ERROR;
+	   
+	 CRC_CHECK :
+	   if(chosen_data[17:0] == {2'b00,CRC})
+	     begin
+		if(~have_space)
+		  state <= ERROR;
+		else
+		  begin
+		     eop_i <= 1;
+		     state <= DONE;
+		  end
+	     end
+	   else if(wait_here)
+	     ;
+	   else
+	     state <= ERROR;
+	 
+	 ERROR :
+	   begin
+	      error_i <= 1;
+	      if(have_space)
+		state <= IDLE;
+	   end
+	 DONE :
+	   begin
+	      state <= IDLE;
+	      eop_i <= 0;
+	   end
+	      
+       endcase // case(state)
+   
+   
+   always @(posedge ser_rx_clk)
+     if(rst_rxclk)
+       CRC <= 16'hFFFF;
+     else if(state == IDLE)
+       CRC <= 16'hFFFF;
+     else if(chosen_data[17:16] == 2'b00)
+       CRC <= nextCRC;
+
+   CRC16_D16 crc_blk(chosen_data[15:0],CRC,nextCRC);
+
+   always @(posedge ser_rx_clk)
+     if(rst_rxclk) write_d <= 0;
+     else write_d <= write_pre;
+
+   // Internal FIFO, size 9 is 2K, size 10 is 4K Bytes
+   assign write = eop_i | (error_i & have_space) | (write_d & (state != CRC_CHECK));
+
+   fifo_2clock_cascade #(.WIDTH(35),.SIZE(FIFOSIZE)) serdes_rx_fifo
+     (.arst(rst),
+      .wclk(ser_rx_clk),.datain({error_i,sop_i,eop_i,line_i}), 
+      .src_rdy_i(write), .dst_rdy_o(have_space), .space(fifo_space), 
+      .rclk(clk),.dataout({error_o,sop_o,eop_o,line_o}), 
+      .src_rdy_o(wr_ready_o), .dst_rdy_i(wr_ready_i), .occupied(fifo_occupied) );
+
+   assign 	       fifo_full = ~have_space;   // Note -- in the wrong clock domain
+   assign 	       fifo_empty = ~wr_ready_o;
+   
+   // Internal FIFO to Buffer interface
+   assign wr_dat_o 		      = line_o;
+   assign wr_flags_o = { 2'b00, eop_o | error_o, sop_o | error_o };
+   
+   wire slu = ~(({2'b11,K_ERROR,K_ERROR}=={ser_rkmsb,ser_rklsb,ser_r}) ||
+		       ({2'b11,K_LOS,K_LOS}=={ser_rkmsb,ser_rklsb,ser_r}));
+   
+   reg [3:0]   slu_reg;
+   
+   always @(posedge clk)
+     if(rst) slu_reg <= 0;
+     else slu_reg <= {slu_reg[2:0],slu};
+
+   always @(posedge clk)
+     serdes_link_up <= &slu_reg[3:1];
+   
+   assign      debug = { have_space, wr_ready_o, odd, sop_i, eop_i, error_i, state[2:0] };
+   
+endmodule // serdes_rx
diff --git a/usrp2/serdes/serdes_tb.v b/usrp2/serdes/serdes_tb.v
new file mode 100644
index 000000000..eb8e019fc
--- /dev/null
+++ b/usrp2/serdes/serdes_tb.v
@@ -0,0 +1,328 @@
+
+// FIXME need to add flow control
+
+module serdes_tb();
+   
+   reg clk, rst;
+   wire ser_rx_clk, ser_tx_clk;
+   wire ser_rklsb, ser_rkmsb, ser_tklsb, ser_tkmsb;
+   wire [15:0] ser_r, ser_t;
+   
+   initial clk = 0;
+   initial rst = 1;
+   initial #1000 rst = 0;
+   always #100 clk = ~clk;
+   
+   // Wishbone
+   reg [31:0]  wb_dat_i;
+   wire [31:0] wb_dat_o_rx, wb_dat_o_tx;
+   reg 	       wb_we, wb_en_rx, wb_en_tx;
+   reg [8:0]   wb_adr;
+
+   // Buffer Control
+   reg 	       go, clear, read, write;
+   reg [3:0]   buf_num;
+   wire [31:0] ctrl_word = {buf_num,3'b0,clear,write,read,step,lastline,firstline};
+   reg [8:0]   firstline = 0, lastline = 0;
+   reg [3:0]   step = 1;
+   reg 	       first_tx = 1, first_rx = 1;  // for verif
+   
+   // TX Side
+   reg 	       wb_we_tx;
+   wire        en_tx, we_tx;
+   wire [8:0]  addr_tx;
+   wire [31:0] f2r_tx, r2f_tx;
+   wire [31:0] data_tx;
+   wire        read_tx, done_tx, error_tx, sop_tx, eop_tx;
+   
+   wire        fdone_tx, ferror_tx;
+   
+   reg 	       even;
+   reg 	       channel_error = 0;
+   
+   serdes_tx serdes_tx
+     (.clk(clk),.rst(rst),
+      .ser_tx_clk(ser_tx_clk),.ser_t(ser_t),.ser_tklsb(ser_tklsb),.ser_tkmsb(ser_tkmsb),
+      .rd_dat_i(data_tx),.rd_read_o(read_tx),.rd_done_o(done_tx),
+      .rd_error_o(error_tx),.rd_sop_i(sop_tx),.rd_eop_i(eop_tx) );
+   
+   ram_2port #(.DWIDTH(32),.AWIDTH(9))
+     ram_tx(.clka(clk),.ena(wb_en_tx),.wea(wb_we_tx),.addra(wb_adr),.dia(wb_dat_i),.doa(wb_dat_o_tx),
+            .clkb(clk),.enb(en_tx),.web(we_tx),.addrb(addr_tx),.dib(f2r_tx),.dob(r2f_tx));
+   
+   buffer_int #(.BUFF_NUM(1)) buffer_int_tx
+     (.clk(clk),.rst(rst),
+      .ctrl_word(ctrl_word),.go(go),
+      .done(fdone_tx),.error(ferror_tx),
+      
+      .en_o(en_tx),.we_o(we_tx),.addr_o(addr_tx),.dat_to_buf(f2r_tx),.dat_from_buf(r2f_tx),
+      
+      .wr_dat_i(0),.wr_write_i(0),.wr_done_i(0),
+      .wr_error_i(0),.wr_ready_o(),.wr_full_o(),
+      
+      .rd_dat_o(data_tx),.rd_read_i(read_tx),.rd_done_i(done_tx),
+      .rd_error_i(error_tx),.rd_sop_o(sop_tx),.rd_eop_o(eop_tx) );
+
+
+   // RX Side
+   reg 	       wb_we_rx;
+   wire        en_rx, we_rx;
+   wire [8:0]  addr_rx;
+   wire [31:0] f2r_rx, r2f_rx;
+   wire [31:0] data_rx;
+   wire        write_rx, done_rx, error_rx, ready_rx, empty_rx;
+   
+   wire        fdone_rx, ferror_rx;
+   
+   serdes_rx serdes_rx
+     (.clk(clk),.rst(rst),
+      .ser_rx_clk(ser_rx_clk),.ser_r(ser_r),.ser_rklsb(ser_rklsb),.ser_rkmsb(ser_rkmsb),
+      .wr_dat_o(data_rx),.wr_write_o(write_rx),.wr_done_o(done_rx),
+      .wr_error_o(error_rx),.wr_ready_i(ready_rx),.wr_full_i(full_rx) );
+
+   ram_2port #(.DWIDTH(32),.AWIDTH(9))
+     ram_rx(.clka(clk),.ena(wb_en_rx),.wea(wb_we_rx),.addra(wb_adr),.dia(wb_dat_i),.doa(wb_dat_o_rx),
+            .clkb(clk),.enb(en_rx),.web(we_rx),.addrb(addr_rx),.dib(f2r_rx),.dob(r2f_rx) );
+   
+   buffer_int #(.BUFF_NUM(0)) buffer_int_rx
+     (.clk(clk),.rst(rst),
+      .ctrl_word(ctrl_word),.go(go),
+      .done(fdone_rx),.error(ferror_rx),
+      
+      .en_o(en_rx),.we_o(we_rx),.addr_o(addr_rx),.dat_to_buf(f2r_rx),.dat_from_buf(r2f_rx),
+      
+      .wr_dat_i(data_rx),.wr_write_i(write_rx),.wr_done_i(done_rx),
+      .wr_error_i(error_rx),.wr_ready_o(ready_rx),.wr_full_o(full_rx),
+      
+      .rd_dat_o(),.rd_read_i(0),.rd_done_i(0),
+      .rd_error_i(0),.rd_sop_o(),.rd_eop_o() );
+
+   // Simulate the connection
+   serdes_model serdes_model
+     (.ser_tx_clk(ser_tx_clk), .ser_tkmsb(ser_tkmsb), .ser_tklsb(ser_tklsb), .ser_t(ser_t),
+      .ser_rx_clk(ser_rx_clk), .ser_rkmsb(ser_rkmsb), .ser_rklsb(ser_rklsb), .ser_r(ser_r),
+      .even(even), .error(channel_error) );
+   
+   initial begin
+      wb_en_rx <= 0;
+      wb_en_tx <=0;
+      wb_we_tx <= 0;
+      wb_we_rx <= 0;
+      wb_adr <= 0;
+      wb_dat_i <= 0;
+      go <= 0;
+      even <= 0;
+      @(negedge rst);
+      @(posedge clk);
+      FillTXRAM;
+      ClearRXRAM;
+      ResetBuffer(0);
+      ResetBuffer(1);
+
+      // receive a full buffer
+      ReceiveSERDES(0,10);
+      SendSERDES(0,10);
+
+      // Receive a partial buffer
+      SendSERDES(11,20);
+      ReceiveSERDES(11,50);
+
+      // Receive too many for buffer
+      SendSERDES(21,100);
+      ReceiveSERDES(21,30);
+
+      // Send 3 packets, then wait to receive them, so they stack up in the rx fifo
+      SendSERDES(31,40);
+      SendSERDES(41,50);
+      SendSERDES(51,60);
+      repeat (10)
+	@(posedge clk);
+      ReceiveSERDES(31,40);
+      ReceiveSERDES(41,50);
+      repeat (1000)
+	@(posedge clk);
+      ReceiveSERDES(51,60);
+
+      // Overfill the FIFO, should get an error on 3rd packet
+      SendSERDES(1,400);
+      SendSERDES(1,400);
+      
+      
+      WaitForTX;
+      //WaitForRX;
+      
+
+      repeat(1000)
+	@(posedge clk);
+      ReceiveSERDES(101,500);
+      ReceiveSERDES(101,500);
+      ReadRAM(80);
+      $finish;
+   end // initial begin
+
+   always @(posedge clk)
+     if(write_rx)
+       $display("SERDES RX, FIFO WRITE %x, FIFO RDY %d, FIFO FULL %d",data_rx, ready_rx, full_rx);
+   
+   always @(posedge clk)
+     if(read_tx)
+       $display("SERDES TX, FIFO READ %x, SOP %d, EOP %d",data_tx, sop_tx, eop_tx);
+   
+   initial begin
+      $dumpfile("serdes_tb.vcd");
+      $dumpvars(0,serdes_tb);
+   end
+
+   initial #10000000 $finish;
+
+   initial #259300 channel_error <= 1;
+   initial #259500 channel_error <= 0;
+   
+   task FillTXRAM;
+      begin
+	 wb_adr <= 0;
+	 wb_dat_i <= 32'h10802000;
+	 wb_we_tx <= 1;
+	 wb_en_tx <= 1;
+	 @(posedge clk);
+	 repeat(511) begin
+	    wb_dat_i <= wb_dat_i + 32'h00010001;
+	    wb_adr <= wb_adr + 1;
+	    @(posedge clk);
+	 end // repeat (511)
+	 wb_we_tx <= 0;
+	 wb_en_tx <= 0;
+	 @(posedge clk);
+	 $display("Done entering Data into TX RAM\n");
+      end
+   endtask // FillTXRAM
+   
+   task ClearRXRAM;
+      begin
+	 wb_adr <= 0;
+	 wb_dat_i <= 0;
+	 wb_we_rx <= 1;
+	 wb_en_rx <= 1;
+	 wb_dat_i <= 0;
+	 @(posedge clk);
+	 repeat(511) begin
+	    wb_adr <= wb_adr + 1;
+	    @(posedge clk);
+	 end // repeat (511)
+	 wb_we_rx <= 0;
+	 wb_en_rx <= 0;
+	 @(posedge clk);
+	 $display("Done clearing RX RAM\n");
+      end
+   endtask // FillRAM
+   
+   task ReadRAM;
+      input [8:0] lastline;
+      begin
+	 wb_en_rx <= 1;
+	 wb_adr <= 0;
+	 @(posedge clk);
+	 @(posedge clk);
+	 repeat(lastline) begin
+	    $display("ADDR: %h  DATA %h", wb_adr, wb_dat_o_rx);
+	    wb_adr <= wb_adr + 1;
+	    @(posedge clk);
+	    @(posedge clk);
+	 end // repeat (511)
+	 $display("ADDR: %h  DATA %h", wb_adr, wb_dat_o_rx);
+	 wb_en_rx <= 0;
+	 @(posedge clk);
+	 $display("Done reading out RX RAM\n");
+      end
+   endtask // FillRAM
+   
+   task ResetBuffer;
+      input [3:0] buffer_num;
+      begin
+	 buf_num <= buffer_num;
+	 clear <= 1; read <= 0; write <= 0;
+	 go <= 1;
+	 @(posedge clk);
+	 go <= 0;
+	 @(posedge clk);
+	 $display("Buffer Reset");
+      end
+   endtask // ClearBuffer
+   
+   task SetBufferWrite;
+      input [3:0] buffer_num;
+      input [8:0] start;
+      input [8:0] stop;
+      begin
+	 buf_num <= buffer_num;
+	 clear <= 0; read <= 0; write <= 1;
+	 firstline <= start;
+	 lastline <= stop;
+	 go <= 1;
+	 @(posedge clk);
+	 go <= 0;
+	 @(posedge clk);
+	 $display("Buffer Set for Write");
+      end
+   endtask // SetBufferWrite
+   
+   task SetBufferRead;
+      input [3:0] buffer_num;
+      input [8:0] start;
+      input [8:0] stop;
+      begin
+	 buf_num <= buffer_num;
+	 clear <= 0; read <= 1; write <= 0;
+	 firstline <= start;
+	 lastline <= stop;
+	 go <= 1;
+	 @(posedge clk);
+	 go <= 0;
+	 @(posedge clk);
+	 $display("Buffer Set for Read");
+      end
+   endtask // SetBufferRead
+
+   task WaitForTX;
+      begin
+	 while (!(fdone_tx | ferror_tx))
+	   @(posedge clk);
+      end
+   endtask // WaitForTX
+   
+   task WaitForRX;
+      begin
+	 while (!(fdone_rx | ferror_rx))
+	   @(posedge clk);
+      end
+   endtask // WaitForRX
+   
+   task SendSERDES;
+      input [8:0] start;
+      input [8:0] stop;
+      begin
+	 if(~first_tx)
+	   WaitForTX;
+	 else
+	   first_tx <= 0;
+	 ResetBuffer(1);
+	 SetBufferRead(1,start,stop);
+	 $display("Here");
+      end
+   endtask // SendSERDES
+   
+   task ReceiveSERDES;
+      input [8:0] start;
+      input [8:0] stop;
+      begin
+	 if(~first_rx)
+	   WaitForRX;
+	 else
+	   first_rx <= 0;
+	 ResetBuffer(0);
+	 SetBufferWrite(0,start,stop);
+	 $display("Here2");
+      end
+   endtask // ReceiveSERDES
+   
+endmodule // serdes_tb
diff --git a/usrp2/serdes/serdes_tx.v b/usrp2/serdes/serdes_tx.v
new file mode 100644
index 000000000..2e5e3bd80
--- /dev/null
+++ b/usrp2/serdes/serdes_tx.v
@@ -0,0 +1,186 @@
+
+// SERDES Interface
+
+// LS-Byte is sent first, MS-Byte is second
+// Invalid K Codes
+//  K0.0  000-00000  Error detected
+//  K31.7 111-11111  Loss of input signal
+
+// Valid K Codes
+//  K28.0 000-11100
+//  K28.1 001-11100  Alternate COMMA?
+//  K28.2 010-11100
+//  K28.3 011-11100
+//  K28.4 100-11100
+//  K28.5 101-11100  Standard COMMA?
+//  K28.6 110-11100
+//  K28.7 111-11100  Bad COMMA?
+//  K23.7 111-10111
+//  K27.7 111-11011
+//  K29.7 111-11101
+//  K30.7 111-11110
+
+module serdes_tx
+  #(parameter FIFOSIZE = 9)
+    (input clk,
+     input rst,
+     
+     // TX HW Interface
+     output ser_tx_clk,
+     output reg [15:0] ser_t,
+     output reg ser_tklsb,
+     output reg ser_tkmsb,
+     
+     // TX Stream Interface
+     input [31:0] rd_dat_i,
+     input [3:0] rd_flags_i,
+     output rd_ready_o,
+     input rd_ready_i,
+
+     // Flow control interface
+     input inhibit_tx,
+     input send_xon,
+     input send_xoff,
+     output sent,
+
+     // FIFO Levels
+     output [15:0] fifo_occupied,
+     output fifo_full,
+     output fifo_empty,
+
+     // DEBUG
+     output [31:0] debug
+     );
+
+   localparam K_COMMA = 8'b101_11100;     // 0xBC K28.5
+   localparam K_IDLE = 8'b001_11100;      // 0x3C K28.1
+   localparam K_PKT_START = 8'b110_11100; // 0xDC K28.6
+   localparam K_PKT_END = 8'b100_11100;   // 0x9C K28.4
+   localparam K_XON = 8'b010_11100;       // 0x5C K28.2
+   localparam K_XOFF = 8'b011_11100;      // 0x7C K28.3
+   localparam K_LOS = 8'b111_11111;       // 0xFF K31.7
+   localparam K_ERROR = 8'b000_00000;     // 0x00 K00.0
+   localparam D_56 = 8'b110_00101;        // 0xC5 D05.6
+   assign     ser_tx_clk = clk;
+   
+   localparam IDLE = 3'd0;
+   localparam RUN1 = 3'd1;
+   localparam RUN2 = 3'd2;
+   localparam DONE = 3'd3;
+   localparam SENDCRC = 3'd4;
+   localparam WAIT = 3'd5;
+   
+   reg [2:0]  state;
+   
+   reg [15:0] CRC;
+   wire [15:0] nextCRC;
+   reg [3:0]   wait_count;
+   
+   // Internal FIFO, size 9 is 2K, size 10 is 4K bytes
+   wire        sop_o, eop_o;
+   wire [31:0] data_o;
+
+   wire        rd_sop_i  = rd_flags_i[0];
+   wire        rd_eop_i  = rd_flags_i[1];
+   wire [1:0]  rd_occ_i = rd_flags_i[3:2];  // Unused
+
+   wire        have_data, empty, read;
+   fifo_cascade #(.WIDTH(34),.SIZE(FIFOSIZE)) serdes_tx_fifo
+     (.clk(clk),.reset(rst),.clear(0),
+      .datain({rd_sop_i,rd_eop_i,rd_dat_i}), .src_rdy_i(rd_ready_i), .dst_rdy_o(rd_ready_o),
+      .dataout({sop_o,eop_o,data_o}), .dst_rdy_i(read), .src_rdy_o(have_data),
+      .space(), .occupied(fifo_occupied) );
+   
+   assign fifo_full   = ~rd_ready_o;
+   assign empty       = ~have_data;
+   assign fifo_empty  = empty;
+   
+   // FIXME Implement flow control   
+   reg [15:0]  second_word;
+   reg [33:0]  pipeline;
+   
+   assign      read = (~send_xon & ~send_xoff & (state==RUN2)) | ((state==IDLE) & ~empty & ~sop_o);
+   assign      sent = send_xon | send_xoff;
+   // 2nd half of above probably not necessary.  Just in case we get junk between packets
+   
+   always @(posedge clk)
+     if(rst)
+       begin
+	  state <= IDLE;
+	  wait_count <= 0;
+	  {ser_tkmsb,ser_tklsb,ser_t} <= 18'd0;
+			//{2'b10,K_COMMA,K_COMMA};  
+	  // make tkmsb and tklsb different so they can go in IOFFs
+       end
+     else
+       if(send_xon)
+	 {ser_tkmsb,ser_tklsb,ser_t} <= {2'b11,K_XON,K_XON};
+       else if(send_xoff)
+	 {ser_tkmsb,ser_tklsb,ser_t} <= {2'b11,K_XOFF,K_XOFF};
+       else
+	 case(state)
+	   IDLE :
+	     begin
+		if(sop_o & ~empty & ~inhibit_tx)
+		  begin
+		     {ser_tkmsb,ser_tklsb,ser_t} <= {2'b11,K_PKT_START,K_PKT_START};
+		     state <= RUN1;
+		  end
+		else
+		  {ser_tkmsb,ser_tklsb,ser_t} <= {2'b10,K_COMMA,D_56};
+	     end
+	   RUN1 :
+	     begin
+		if(empty | inhibit_tx)
+		  {ser_tkmsb,ser_tklsb,ser_t} <= {2'b10,K_COMMA,D_56};
+		else
+		  begin
+		     {ser_tkmsb,ser_tklsb,ser_t} <= {2'b00,data_o[15:0]};
+		     state <= RUN2;
+		  end
+	     end
+	   RUN2 :
+	     begin
+		{ser_tkmsb,ser_tklsb,ser_t} <= {2'b00,data_o[31:16]};
+		if(eop_o)
+		  state <= DONE;
+		else
+		  state <= RUN1;
+	     end
+	   DONE :
+	     begin
+		{ser_tkmsb,ser_tklsb,ser_t} <= {2'b11,K_PKT_END,K_PKT_END};
+		state <= SENDCRC;
+	     end
+	   SENDCRC :
+	     begin
+		{ser_tkmsb,ser_tklsb,ser_t} <= {2'b00,CRC};
+		state <= WAIT;
+		wait_count <= 4'd15;
+	     end
+	   WAIT :
+	     begin
+		{ser_tkmsb,ser_tklsb,ser_t} <= {2'b10,K_COMMA,D_56};
+		if(wait_count == 0)
+		  state <= IDLE;
+		else
+		  wait_count <= wait_count - 1;
+	     end
+	   default
+	     state <= IDLE;
+	 endcase // case(state)
+   
+   always @(posedge clk)
+     if(rst)
+       CRC <= 16'hFFFF;
+     else if(state == IDLE)
+       CRC <= 16'hFFFF;
+     else if( (~empty & ~inhibit_tx & (state==RUN1)) || (state==RUN2) )
+       CRC <= nextCRC;
+   
+   CRC16_D16 crc_blk( (state==RUN1) ? data_o[15:0] : data_o[31:16], CRC, nextCRC);
+
+   assign debug = { 28'd0, state[2:0] };
+   
+endmodule // serdes_tx
+