e100: squashed work on bus implementation on GPMC

22 files changed, 545 insertions, 984 deletions

diff --git a/usrp2/gpmc/Makefile.srcs b/usrp2/gpmc/Makefile.srcs
index bff6ae3e0..4c6a1b4a2 100644
--- a/usrp2/gpmc/Makefile.srcs
+++ b/usrp2/gpmc/Makefile.srcs
@@ -1,20 +1,14 @@
 #
-# Copyright 2010 Ettus Research LLC
+# Copyright 2010-2011 Ettus Research LLC
 #
 
 ##################################################
-# SERDES Sources
+# GPMC Sources
 ##################################################
 GPMC_SRCS = $(abspath $(addprefix $(BASE_DIR)/../gpmc/, \
-dbsm.v \
-edge_sync.v \
-fifo_to_gpmc_async.v \
-fifo_to_gpmc_sync.v \
-fifo_watcher.v \
-gpmc_async.v \
-gpmc_sync.v \
-gpmc_to_fifo_async.v \
-gpmc_to_fifo_sync.v \
+cross_clock_reader.v \
+fifo_to_gpmc.v \
+gpmc.v \
+gpmc_to_fifo.v \
 gpmc_wb.v \
-ram_to_fifo.v \
 ))
diff --git a/usrp2/gpmc/burst_data_write.txt b/usrp2/gpmc/burst_data_write.txt
deleted file mode 100644
index 3b5dfc785..000000000
--- a/usrp2/gpmc/burst_data_write.txt
+++ /dev/null
@@ -1,16 +0,0 @@
-# OMAP burst writes to FPGA
-
-CLK=0,nWE=1,nCS=1,nOE=1,DATA=Z.
-CLK=1.
-CLK=0,nWE=0,nCS=0,DATA=WR_DATA1.
-CLK=1.
-CLK=0,nWE=0,nCS=0,DATA=WR_DATA2.
-CLK=1.
-CLK=0,nWE=0,nCS=0,DATA=WR_DATA3.
-CLK=1.
-CLK=0,nWE=0,nCS=0,DATA=WR_DATA4.
-CLK=1.
-CLK=0,nWE=1,nCS=1,DATA=Z.
-CLK=1.
-
-
diff --git a/usrp2/gpmc/edge_sync.v b/usrp2/gpmc/cross_clock_reader.v
index 74f1a2f1c..a30e0385f 100644
--- a/usrp2/gpmc/edge_sync.v
+++ b/usrp2/gpmc/cross_clock_reader.v
@@ -15,25 +15,28 @@
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 //
 
+module cross_clock_reader
+    #(
+        parameter WIDTH = 1,
+        parameter DEFAULT = 0
+    )
+    (
+        input clk, input rst,
+        input [WIDTH-1:0] in,
+        output reg [WIDTH-1:0] out
+    );
 
+    reg [WIDTH-1:0] shadow;
 
-module edge_sync
-  #(parameter POSEDGE = 1)
-   (input clk,
-    input rst,
-    input sig,
-    output trig);
-   
-   reg [1:0] delay;
-   
-   always @(posedge clk)
-     if(rst)
-       delay <= 2'b00;
-     else
-       delay <= {delay[0],sig};
-   
-   assign trig = POSEDGE ? (delay==2'b01) : (delay==2'b10);
-   
-endmodule // edge_sync
-
+    always @(posedge clk) begin
+        if (rst) begin
+            out <= DEFAULT;
+            shadow <= DEFAULT;
+        end
+        else if (shadow == in) begin
+            out <= shadow;
+        end
+        shadow <= in;
+    end
 
+endmodule //cross_clock_reader
diff --git a/usrp2/gpmc/dbsm.v b/usrp2/gpmc/dbsm.v
deleted file mode 100644
index 1ee250738..000000000
--- a/usrp2/gpmc/dbsm.v
+++ /dev/null
@@ -1,97 +0,0 @@
-//
-// Copyright 2011 Ettus Research LLC
-//
-// This program is free software: you can redistribute it and/or modify
-// it under the terms of the GNU General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-//
-// This program is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU General Public License for more details.
-//
-// You should have received a copy of the GNU General Public License
-// along with this program.  If not, see <http://www.gnu.org/licenses/>.
-//
-
-
-module bsm
-  (input clk, input reset, input clear,
-   input write_done,
-   input read_done,
-   output readable,
-   output writeable);
-
-   reg 	  state;
-   localparam ST_WRITEABLE = 0;
-   localparam ST_READABLE = 1;
-   
-   always @(posedge clk)
-     if(reset | clear)
-       state <= ST_WRITEABLE;
-     else
-       case(state)
-	 ST_WRITEABLE :
-	   if(write_done)
-	     state <= ST_READABLE;
-	 ST_READABLE :
-	   if(read_done)
-	     state <= ST_WRITEABLE;
-       endcase // case (state)
-
-   assign readable = (state == ST_READABLE);
-   assign writeable = (state == ST_WRITEABLE);
-   
-endmodule // bsm
-
-module dbsm
-  (input clk, input reset, input clear,
-   output reg read_sel, output read_ready, input read_done,
-   output reg write_sel, output write_ready, input write_done);
-
-   localparam NUM_BUFS = 2;
-
-   wire       [NUM_BUFS-1:0] readable, writeable, read_done_buf, write_done_buf;
-   
-   // Two of these buffer state machines
-   genvar     i;
-   generate
-      for(i=0;i<NUM_BUFS;i=i+1)
-	begin : BSMS
-	   bsm bsm(.clk(clk), .reset(reset), .clear(clear),
-		   .write_done((write_sel == i) & write_done),
-		   .read_done((read_sel == i) & read_done),
-		   .readable(readable[i]), .writeable(writeable[i]));
-	end
-   endgenerate
-   
-   reg 	 full;
-   
-   always @(posedge clk)
-     if(reset | clear)
-       begin
-	  write_sel <= 0;
-	  full <= 0;
-       end
-     else
-       if(write_done & writeable[write_sel])
-	 if(write_sel ==(NUM_BUFS-1))
-	   write_sel <= 0;
-	 else
-	   write_sel <= write_sel + 1;
-   
-   always @(posedge clk)
-     if(reset | clear)
-       read_sel <= 0;
-     else
-       if(read_done & readable[read_sel])
-	 if(read_sel==(NUM_BUFS-1))
-	   read_sel <= 0;
-	 else
-	   read_sel <= read_sel + 1;
-          
-   assign write_ready = writeable[write_sel];
-   assign read_ready = readable[read_sel];
-
-endmodule // dbsm
diff --git a/usrp2/gpmc/fifo_to_gpmc.v b/usrp2/gpmc/fifo_to_gpmc.v
new file mode 100644
index 000000000..42c71d2d6
--- /dev/null
+++ b/usrp2/gpmc/fifo_to_gpmc.v
@@ -0,0 +1,159 @@
+//
+// Copyright 2011 Ettus Research LLC
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+//
+
+////////////////////////////////////////////////////////////////////////
+// FIFO to GPMC
+//
+// Reads frames from FIFO interface and writes them into BRAM pages.
+// The GPMC is asynchronously alerted when a BRAM page has been filled.
+//
+// EM_CLK:
+// A GPMC read transaction consists of two EM_CLK cycles (idle low).
+//
+// EM_OE:
+// Output enable is actually the combination of ~NOE & ~NCS.
+// The output enable is only active for the second rising edge,
+// to ensure one edge per transaction to transition on.
+//
+// EM_D:
+// The BRAM performs a read on the first rising edge into EM_D.
+// Then, data will then be read on the next rising edge by GPMC.
+//
+// EM_A:
+// On the first rising edge of EM_CLK, the address is held.
+// On the second rising edge, the address is set for the next transaction.
+////////////////////////////////////////////////////////////////////////
+
+module fifo_to_gpmc
+  #(parameter PTR_WIDTH = 2, parameter ADDR_WIDTH = 10)
+  (input clk, input reset, input clear, input arst,
+   input [17:0] data_i, input src_rdy_i, output dst_rdy_o,
+   output [15:0] EM_D, input [ADDR_WIDTH:1] EM_A, input EM_CLK, input EM_OE,
+   output reg data_available);
+
+    //states for the GPMC side of things
+    wire [17:0] data_o;
+    reg gpmc_state;
+    reg [ADDR_WIDTH:1] addr;
+    reg [PTR_WIDTH:0] gpmc_ptr, next_gpmc_ptr;
+    localparam GPMC_STATE_START = 0;
+    localparam GPMC_STATE_EMPTY = 1;
+
+    //states for the FIFO side of things
+    reg fifo_state;
+    reg [ADDR_WIDTH-1:0] counter;
+    reg [PTR_WIDTH:0] fifo_ptr;
+    localparam FIFO_STATE_CLAIM = 0;
+    localparam FIFO_STATE_FILL = 1;
+
+    //------------------------------------------------------------------
+    // State machine to control the data from GPMC to BRAM
+    //------------------------------------------------------------------
+    always @(posedge EM_CLK or posedge arst) begin
+        if (arst) begin
+            gpmc_state <= GPMC_STATE_START;
+            gpmc_ptr <= 0;
+            next_gpmc_ptr <= 0;
+            addr <= 0;
+        end
+        else if (EM_OE) begin
+            addr <= EM_A + 1;
+            case(gpmc_state)
+
+            GPMC_STATE_START: begin
+                if (EM_A == 0) begin
+                    gpmc_state <= GPMC_STATE_EMPTY;
+                    next_gpmc_ptr <= gpmc_ptr + 1;
+                end
+            end
+
+            GPMC_STATE_EMPTY: begin
+                if (EM_A == 10'h3ff) begin
+                    gpmc_state <= GPMC_STATE_START;
+                    gpmc_ptr <= next_gpmc_ptr;
+                end
+            end
+
+            endcase //gpmc_state
+        end //EM_WE
+    end //always
+
+    //------------------------------------------------------------------
+    // High when the gpmc pointer has not caught up to the fifo pointer.
+    //------------------------------------------------------------------
+    wire [PTR_WIDTH:0] safe_gpmc_ptr;
+    cross_clock_reader #(.WIDTH(PTR_WIDTH+1)) read_gpmc_ptr
+        (.clk(clk), .rst(reset | clear), .in(gpmc_ptr), .out(safe_gpmc_ptr));
+
+    wire bram_available_to_fill = (fifo_ptr ^ (1 << PTR_WIDTH)) != safe_gpmc_ptr;
+
+    //------------------------------------------------------------------
+    // Glich free generation of data available signal:
+    // Data is available when the pointers dont match.
+    //------------------------------------------------------------------
+    wire [PTR_WIDTH:0] safe_next_gpmc_ptr;
+    cross_clock_reader #(.WIDTH(PTR_WIDTH+1)) read_next_gpmc_ptr
+        (.clk(clk), .rst(reset | clear), .in(next_gpmc_ptr), .out(safe_next_gpmc_ptr));
+
+    always @(posedge clk)
+        if (reset | clear) data_available <= 0;
+        else               data_available <= safe_next_gpmc_ptr != fifo_ptr;
+
+    //------------------------------------------------------------------
+    // State machine to control the data from BRAM to FIFO
+    //------------------------------------------------------------------
+    always @(posedge clk) begin
+        if (reset | clear) begin
+            fifo_state <= FIFO_STATE_CLAIM;
+            fifo_ptr <= 0;
+            counter <= 0;
+        end
+        else begin
+            case(fifo_state)
+
+            FIFO_STATE_CLAIM: begin
+                if (bram_available_to_fill) fifo_state <= FIFO_STATE_FILL;
+                counter <= 0;
+            end
+
+            FIFO_STATE_FILL: begin
+                if (src_rdy_i && dst_rdy_o && data_i[17]) begin
+                    fifo_state <= FIFO_STATE_CLAIM;
+                    fifo_ptr <= fifo_ptr + 1;
+                end
+                if (src_rdy_i && dst_rdy_o) begin
+                    counter <= counter + 1;
+                end
+            end
+
+            endcase //fifo_state
+        end
+    end //always
+
+    assign dst_rdy_o = fifo_state == FIFO_STATE_FILL;
+
+    //assign data from bram output
+    assign EM_D = data_o[15:0];
+
+    //instantiate dual ported bram for async read + write
+    ram_2port #(.DWIDTH(18),.AWIDTH(PTR_WIDTH + ADDR_WIDTH)) async_fifo_bram
+     (.clka(clk),.ena(1'b1),.wea(src_rdy_i && dst_rdy_o),
+      .addra({fifo_ptr[PTR_WIDTH-1:0], counter}),.dia(data_i),.doa(),
+      .clkb(EM_CLK),.enb(1'b1),.web(1'b0),
+      .addrb({gpmc_ptr[PTR_WIDTH-1:0], addr}),.dib(18'h3ffff),.dob(data_o));
+
+endmodule // fifo_to_gpmc
diff --git a/usrp2/gpmc/fifo_to_gpmc_async.v b/usrp2/gpmc/fifo_to_gpmc_async.v
deleted file mode 100644
index bb4c58ec4..000000000
--- a/usrp2/gpmc/fifo_to_gpmc_async.v
+++ /dev/null
@@ -1,49 +0,0 @@
-//
-// Copyright 2011 Ettus Research LLC
-//
-// This program is free software: you can redistribute it and/or modify
-// it under the terms of the GNU General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-//
-// This program is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU General Public License for more details.
-//
-// You should have received a copy of the GNU General Public License
-// along with this program.  If not, see <http://www.gnu.org/licenses/>.
-//
-
-
-module fifo_to_gpmc_async
-  (input clk, input reset, input clear,
-   input [17:0] data_i, input src_rdy_i, output dst_rdy_o,
-   output [15:0] EM_D, input EM_NCS, input EM_NOE,
-   input [15:0] frame_len);
-
-   // Synchronize the async control signals
-   reg [2:0] 	cs_del, oe_del;
-   reg [15:0] 	counter;
-   
-   always @(posedge clk)
-     if(reset)
-       begin
-	  cs_del <= 3'b11;
-	  oe_del <= 3'b11;
-       end
-     else
-       begin
-	  cs_del <= { cs_del[1:0], EM_NCS };
-	  oe_del <= { oe_del[1:0], EM_NOE };
-       end
-
-   wire do_read = ( (~cs_del[1] | ~cs_del[2]) & (oe_del[1:0] == 2'b01));  // change output on trailing edge
-   wire first_read = (counter == 0);
-   wire last_read = ((counter+1) == frame_len);
-
-   assign EM_D = data_i[15:0];
-
-   assign dst_rdy_o = do_read;
-
-endmodule // fifo_to_gpmc_async
diff --git a/usrp2/gpmc/fifo_to_gpmc_sync.v b/usrp2/gpmc/fifo_to_gpmc_sync.v
deleted file mode 100644
index 9da9caf86..000000000
--- a/usrp2/gpmc/fifo_to_gpmc_sync.v
+++ /dev/null
@@ -1,43 +0,0 @@
-//
-// Copyright 2011 Ettus Research LLC
-//
-// This program is free software: you can redistribute it and/or modify
-// it under the terms of the GNU General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-//
-// This program is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU General Public License for more details.
-//
-// You should have received a copy of the GNU General Public License
-// along with this program.  If not, see <http://www.gnu.org/licenses/>.
-//
-
-
-// Assumes a GPMC cycle with GPMC clock, as in the timing diagrams
-//   If a packet bigger or smaller than we are told is sent, behavior is undefined.
-//   If dst_rdy_i is low when we get data, behavior is undefined and we signal bus error.
-//   If there is a bus error, we should be reset
-
-module fifo_to_gpmc_sync
-  (input arst,
-   input [17:0] data_i, input src_rdy_i, output dst_rdy_o,
-   input EM_CLK, output [15:0] EM_D, input EM_NCS, input EM_NOE,
-   output fifo_ready, 
-   output reg bus_error);
-
-   assign EM_D = data_i[15:0];
-   wire       read_access = ~EM_NCS & ~EM_NOE;
-
-   assign dst_rdy_o = read_access;
-
-   always @(posedge EM_CLK or posedge arst)
-     if(arst)
-       bus_error <= 0;
-     else if(dst_rdy_o & ~src_rdy_i)
-       bus_error <= 1;
-   
-
-endmodule // fifo_to_gpmc_sync
diff --git a/usrp2/gpmc/fifo_watcher.v b/usrp2/gpmc/fifo_watcher.v
deleted file mode 100644
index b139f5143..000000000
--- a/usrp2/gpmc/fifo_watcher.v
+++ /dev/null
@@ -1,73 +0,0 @@
-//
-// Copyright 2011 Ettus Research LLC
-//
-// This program is free software: you can redistribute it and/or modify
-// it under the terms of the GNU General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-//
-// This program is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU General Public License for more details.
-//
-// You should have received a copy of the GNU General Public License
-// along with this program.  If not, see <http://www.gnu.org/licenses/>.
-//
-
-
-
-module fifo_watcher
-  (input clk, input reset, input clear,
-   input src_rdy1, input dst_rdy1, input sof1, input eof1,
-   input src_rdy2, input dst_rdy2, input sof2, input eof2,
-   output reg have_packet, output [15:0] length, output reg bus_error,
-   output [31:0] debug);
-
-   wire   write = src_rdy1 & dst_rdy1 & eof1;
-   wire   read = src_rdy2 & dst_rdy2 & eof2;
-   wire   have_packet_int;
-   reg [15:0] counter;
-   wire [4:0] pkt_count;
-   assign debug = pkt_count;
-   
-   fifo_short #(.WIDTH(16)) frame_lengths
-     (.clk(clk), .reset(reset), .clear(clear),
-      .datain(counter), .src_rdy_i(write), .dst_rdy_o(),
-      .dataout(length), .src_rdy_o(have_packet_int), .dst_rdy_i(read),
-      .occupied(pkt_count), .space());
-
-   always @(posedge clk)
-     if(reset | clear)
-       counter <= 1;   // Start at 1
-     else if(src_rdy1 & dst_rdy1)
-       if(eof1)
-	 counter <= 1;
-       else
-	 counter <= counter + 1;
-
-   always @(posedge clk)
-     if(reset | clear)
-       bus_error <= 0;
-     else if(dst_rdy2 & ~src_rdy2)
-       bus_error <= 1;
-     else if(read & ~have_packet_int)
-       bus_error <= 1;
-
-   reg 	      in_packet;
-   always @(posedge clk)
-     if(reset | clear)
-       have_packet <= 0;
-     else 
-       have_packet <= (have_packet_int & ~in_packet) | (pkt_count>1) ;
-   
-   always @(posedge clk)
-     if(reset | clear)
-       in_packet <= 0;
-     else if(src_rdy2 & dst_rdy2)
-       if(eof2)
-	 in_packet <= 0;
-       else
-	 in_packet <= 1;
-   
-endmodule // fifo_watcher
diff --git a/usrp2/gpmc/gpmc.v b/usrp2/gpmc/gpmc.v
new file mode 100644
index 000000000..a5d4db466
--- /dev/null
+++ b/usrp2/gpmc/gpmc.v
@@ -0,0 +1,159 @@
+//
+// Copyright 2011 Ettus Research LLC
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+//
+
+//////////////////////////////////////////////////////////////////////////////////
+
+module gpmc
+  #(parameter TXFIFOSIZE = 11, 
+    parameter RXFIFOSIZE = 11,
+    parameter ADDR_WIDTH = 10,
+    parameter BUSDEBUG = 1)
+   (// GPMC signals
+    input arst,
+    input EM_CLK, inout [15:0] EM_D, input [ADDR_WIDTH:1] EM_A, input [1:0] EM_NBE,
+    input EM_WAIT0, input EM_NCS4, input EM_NCS6, input EM_NWE, input EM_NOE,
+    
+    // GPIOs for FIFO signalling
+    output rx_have_data, output tx_have_space,
+    
+    // Wishbone signals
+    input wb_clk, input wb_rst,
+    output [ADDR_WIDTH:0] wb_adr_o, output [15:0] wb_dat_mosi, input [15:0] wb_dat_miso,
+    output [1:0] wb_sel_o, output wb_cyc_o, output wb_stb_o, output wb_we_o, input wb_ack_i,
+    
+    // FIFO interface
+    input fifo_clk, input fifo_rst, input clear_tx, input clear_rx,
+    output [35:0] tx_data_o, output tx_src_rdy_o, input tx_dst_rdy_i,
+    input [35:0] rx_data_i, input rx_src_rdy_i, output rx_dst_rdy_o,
+
+    output tx_underrun, output rx_overrun,
+    input [7:0] test_rate, input [3:0] test_ctrl,
+    output [31:0] debug
+    );
+
+   wire 	  EM_output_enable = (~EM_NOE & (~EM_NCS4 | ~EM_NCS6));
+   wire [15:0] 	  EM_D_fifo;
+   wire [15:0] 	  EM_D_wb;
+
+   assign EM_D = ~EM_output_enable ? 16'bz : ~EM_NCS4 ? EM_D_fifo : EM_D_wb;
+
+   // CS4 is RAM_2PORT for DATA PATH (high-speed data)
+   //    Writes go into one RAM, reads come from the other
+   // CS6 is for CONTROL PATH (wishbone)
+
+   // ////////////////////////////////////////////
+   // TX Data Path
+
+   wire [17:0] 	  tx18_data;
+   wire 	  tx18_src_rdy, tx18_dst_rdy;
+   wire [35:0] 	  tx_data, txb_data;
+   wire 	  tx_src_rdy, tx_dst_rdy;
+   wire 	  txb_src_rdy, txb_dst_rdy;
+
+   gpmc_to_fifo #(.ADDR_WIDTH(ADDR_WIDTH)) gpmc_to_fifo
+     (.EM_D(EM_D), .EM_A(EM_A), .EM_CLK(EM_CLK), .EM_WE(~EM_NCS4 & ~EM_NWE),
+      .clk(fifo_clk), .reset(fifo_rst), .clear(clear_tx), .arst(fifo_rst | clear_tx | arst),
+      .data_o(tx18_data), .src_rdy_o(tx18_src_rdy), .dst_rdy_i(tx18_dst_rdy),
+      .have_space(tx_have_space));
+
+   fifo19_to_fifo36 #(.LE(1)) f19_to_f36   // Little endian because ARM is LE
+     (.clk(fifo_clk), .reset(fifo_rst), .clear(clear_tx),
+      .f19_datain({1'b0,tx18_data}), .f19_src_rdy_i(tx18_src_rdy), .f19_dst_rdy_o(tx18_dst_rdy),
+      .f36_dataout(txb_data), .f36_src_rdy_o(txb_src_rdy), .f36_dst_rdy_i(txb_dst_rdy));
+
+   fifo_cascade #(.WIDTH(36), .SIZE(TXFIFOSIZE)) tx_buffering(
+        .clk(fifo_clk), .reset(fifo_rst), .clear(clear_tx),
+        .datain(txb_data), .src_rdy_i(txb_src_rdy), .dst_rdy_o(txb_dst_rdy),
+        .dataout(tx_data), .src_rdy_o(tx_src_rdy), .dst_rdy_i(tx_dst_rdy)
+   );
+
+   // ////////////////////////////////////////////
+   // RX Data Path
+   
+   wire [17:0] 	  rx18_data;
+   wire 	  rx18_src_rdy, rx18_dst_rdy;
+   wire [35:0] 	  rx_data, rxb_data;
+   wire 	  rx_src_rdy, rx_dst_rdy;
+   wire 	  rxb_src_rdy, rxb_dst_rdy;
+   wire 	  dummy;
+
+   fifo_cascade #(.WIDTH(36), .SIZE(RXFIFOSIZE)) rx_buffering(
+        .clk(fifo_clk), .reset(fifo_rst), .clear(clear_rx),
+        .datain(rx_data), .src_rdy_i(rx_src_rdy), .dst_rdy_o(rx_dst_rdy),
+        .dataout(rxb_data), .src_rdy_o(rxb_src_rdy), .dst_rdy_i(rxb_dst_rdy)
+   );
+
+   fifo36_to_fifo19 #(.LE(1)) f36_to_f19   // Little endian because ARM is LE
+     (.clk(fifo_clk), .reset(fifo_rst), .clear(clear_rx),
+      .f36_datain(rxb_data), .f36_src_rdy_i(rxb_src_rdy), .f36_dst_rdy_o(rxb_dst_rdy),
+      .f19_dataout({dummy,rx18_data}), .f19_src_rdy_o(rx18_src_rdy), .f19_dst_rdy_i(rx18_dst_rdy) );
+
+   fifo_to_gpmc #(.ADDR_WIDTH(ADDR_WIDTH)) fifo_to_gpmc
+     (.clk(fifo_clk), .reset(fifo_rst), .clear(clear_rx), .arst(fifo_rst | clear_rx | arst),
+      .data_i(rx18_data), .src_rdy_i(rx18_src_rdy), .dst_rdy_o(rx18_dst_rdy),
+      .EM_D(EM_D_fifo), .EM_A(EM_A), .EM_CLK(EM_CLK), .EM_OE(~EM_NCS4 & ~EM_NOE),
+      .data_available(rx_have_data));
+
+   // ////////////////////////////////////////////
+   // Control path on CS6
+   
+   gpmc_wb gpmc_wb
+     (.EM_CLK(EM_CLK), .EM_D_in(EM_D), .EM_D_out(EM_D_wb), .EM_A(EM_A), .EM_NBE(EM_NBE),
+      .EM_WE(~EM_NCS6 & ~EM_NWE), .EM_OE(~EM_NCS6 & ~EM_NOE),
+      .wb_clk(wb_clk), .wb_rst(wb_rst),
+      .wb_adr_o(wb_adr_o), .wb_dat_mosi(wb_dat_mosi), .wb_dat_miso(wb_dat_miso),
+      .wb_sel_o(wb_sel_o), .wb_cyc_o(wb_cyc_o), .wb_stb_o(wb_stb_o), .wb_we_o(wb_we_o),
+      .wb_ack_i(wb_ack_i) );
+
+   // ////////////////////////////////////////////
+   // Test support, traffic generator, loopback, etc.
+
+   // RX side muxes test data into the same stream
+   wire [35:0] loopbackrx_data, testrx_data;
+   wire [35:0] loopbacktx_data, testtx_data;
+   wire        loopbackrx_src_rdy, loopbackrx_dst_rdy;
+   wire        loopbacktx_src_rdy, loopbacktx_dst_rdy;
+   wire        sel_testtx = test_ctrl[0];
+
+   fifo36_mux rx_test_mux_lvl_2
+     (.clk(fifo_clk), .reset(fifo_rst), .clear(clear_rx),
+      .data0_i(loopbackrx_data), .src0_rdy_i(loopbackrx_src_rdy), .dst0_rdy_o(loopbackrx_dst_rdy),
+      .data1_i(rx_data_i), .src1_rdy_i(rx_src_rdy_i), .dst1_rdy_o(rx_dst_rdy_o),
+      .data_o(rx_data), .src_rdy_o(rx_src_rdy), .dst_rdy_i(rx_dst_rdy));
+
+   fifo_short #(.WIDTH(36)) loopback_fifo
+     (.clk(fifo_clk), .reset(fifo_rst), .clear(clear_tx | clear_rx),
+      .datain(loopbacktx_data), .src_rdy_i(loopbacktx_src_rdy), .dst_rdy_o(loopbacktx_dst_rdy),
+      .dataout(loopbackrx_data), .src_rdy_o(loopbackrx_src_rdy), .dst_rdy_i(loopbackrx_dst_rdy));
+
+   // Crossbar used as a demux for switching TX stream to main DSP or to test logic
+   crossbar36 tx_crossbar_lvl_1
+     (.clk(fifo_clk), .reset(fifo_rst), .clear(clear_tx),
+      .cross(sel_testtx),
+      .data0_i(tx_data), .src0_rdy_i(tx_src_rdy), .dst0_rdy_o(tx_dst_rdy),
+      .data1_i(tx_data), .src1_rdy_i(1'b0), .dst1_rdy_o(),  // No 2nd input
+      .data0_o(tx_data_o), .src0_rdy_o(tx_src_rdy_o), .dst0_rdy_i(tx_dst_rdy_i),
+      .data1_o(loopbacktx_data), .src1_rdy_o(loopbacktx_src_rdy), .dst1_rdy_i(loopbacktx_dst_rdy) );
+
+   assign debug = {
+        EM_D, //16
+        EM_A, //10
+        EM_CLK, EM_NCS4, EM_NWE, EM_NOE, //4
+        EM_NCS6, wb_ack_i
+   };
+
+endmodule // gpmc
diff --git a/usrp2/gpmc/gpmc_async.v b/usrp2/gpmc/gpmc_async.v
deleted file mode 100644
index c0bec683a..000000000
--- a/usrp2/gpmc/gpmc_async.v
+++ /dev/null
@@ -1,245 +0,0 @@
-//
-// Copyright 2011 Ettus Research LLC
-//
-// This program is free software: you can redistribute it and/or modify
-// it under the terms of the GNU General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-//
-// This program is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU General Public License for more details.
-//
-// You should have received a copy of the GNU General Public License
-// along with this program.  If not, see <http://www.gnu.org/licenses/>.
-//
-
-//////////////////////////////////////////////////////////////////////////////////
-
-module gpmc_async
-  #(parameter TXFIFOSIZE = 11, 
-    parameter RXFIFOSIZE = 11,
-    parameter BUSDEBUG = 1)
-   (// GPMC signals
-    input arst,
-    input EM_CLK, inout [15:0] EM_D, input [10:1] EM_A, input [1:0] EM_NBE,
-    input EM_WAIT0, input EM_NCS4, input EM_NCS6, input EM_NWE, input EM_NOE,
-    
-    // GPIOs for FIFO signalling
-    output rx_have_data, output tx_have_space, output reg bus_error, input bus_reset,
-    
-    // Wishbone signals
-    input wb_clk, input wb_rst,
-    output [10:0] wb_adr_o, output [15:0] wb_dat_mosi, input [15:0] wb_dat_miso,
-    output [1:0] wb_sel_o, output wb_cyc_o, output wb_stb_o, output wb_we_o, input wb_ack_i,
-    
-    // FIFO interface
-    input fifo_clk, input fifo_rst, input clear_tx, input clear_rx,
-    output [35:0] tx_data_o, output tx_src_rdy_o, input tx_dst_rdy_i,
-    input [35:0] rx_data_i, input rx_src_rdy_i, output rx_dst_rdy_o,
-    
-    input [15:0] tx_frame_len, output [15:0] rx_frame_len,
-
-    output tx_underrun, output rx_overrun,
-    input [7:0] test_rate, input [3:0] test_ctrl,
-    output [31:0] debug
-    );
-
-   wire 	  EM_output_enable = (~EM_NOE & (~EM_NCS4 | ~EM_NCS6));
-   wire [15:0] 	  EM_D_fifo;
-   wire [15:0] 	  EM_D_wb;
-   
-   assign EM_D = ~EM_output_enable ? 16'bz : ~EM_NCS4 ? EM_D_fifo : EM_D_wb;
-   
-   wire 	  bus_error_tx, bus_error_rx;
-   
-   always @(posedge fifo_clk)
-     if(fifo_rst | clear_tx | clear_rx)
-       bus_error <= 0;
-     else
-       bus_error <= bus_error_tx | bus_error_rx;
-   
-   // CS4 is RAM_2PORT for DATA PATH (high-speed data)
-   //    Writes go into one RAM, reads come from the other
-   // CS6 is for CONTROL PATH (wishbone)
-
-   // ////////////////////////////////////////////
-   // TX Data Path
-
-   wire [17:0] 	  tx18_data, tx18b_data;
-   wire 	  tx18_src_rdy, tx18_dst_rdy, tx18b_src_rdy, tx18b_dst_rdy;
-   wire [15:0] 	  tx_fifo_space;
-   wire [35:0] 	  tx36_data, tx_data;
-   wire 	  tx36_src_rdy, tx36_dst_rdy, tx_src_rdy, tx_dst_rdy;
-   
-   gpmc_to_fifo_async gpmc_to_fifo_async
-     (.EM_D(EM_D), .EM_NBE(EM_NBE), .EM_NCS(EM_NCS4), .EM_NWE(EM_NWE),
-      .fifo_clk(fifo_clk), .fifo_rst(fifo_rst), .clear(clear_tx),
-      .data_o(tx18_data), .src_rdy_o(tx18_src_rdy), .dst_rdy_i(tx18_dst_rdy),
-      .frame_len(tx_frame_len), .fifo_space(tx_fifo_space), .fifo_ready(tx_have_space),
-      .bus_error(bus_error_tx) );
-   
-   fifo_cascade #(.WIDTH(18), .SIZE(10)) tx_fifo
-     (.clk(fifo_clk), .reset(fifo_rst), .clear(clear_tx),
-      .datain(tx18_data), .src_rdy_i(tx18_src_rdy), .dst_rdy_o(tx18_dst_rdy), .space(tx_fifo_space),
-      .dataout(tx18b_data), .src_rdy_o(tx18b_src_rdy), .dst_rdy_i(tx18b_dst_rdy), .occupied());
-
-   fifo19_to_fifo36 #(.LE(1)) f19_to_f36   // Little endian because ARM is LE
-     (.clk(fifo_clk), .reset(fifo_rst), .clear(clear_tx),
-      .f19_datain({1'b0,tx18b_data}), .f19_src_rdy_i(tx18b_src_rdy), .f19_dst_rdy_o(tx18b_dst_rdy),
-      .f36_dataout(tx36_data), .f36_src_rdy_o(tx36_src_rdy), .f36_dst_rdy_i(tx36_dst_rdy));
-   
-   fifo_cascade #(.WIDTH(36), .SIZE(TXFIFOSIZE)) tx_fifo36
-     (.clk(fifo_clk), .reset(fifo_rst), .clear(clear_tx),
-      .datain(tx36_data), .src_rdy_i(tx36_src_rdy), .dst_rdy_o(tx36_dst_rdy),
-      .dataout(tx_data), .src_rdy_o(tx_src_rdy), .dst_rdy_i(tx_dst_rdy));
-
-   // ////////////////////////////////////////////
-   // RX Data Path
-   
-   wire [17:0] 	  rx18_data, rx18b_data;
-   wire 	  rx18_src_rdy, rx18_dst_rdy, rx18b_src_rdy, rx18b_dst_rdy;
-   wire [15:0] 	  rx_fifo_space;
-   wire [35:0] 	  rx36_data, rx_data;
-   wire 	  rx36_src_rdy, rx36_dst_rdy, rx_src_rdy, rx_dst_rdy;
-   wire 	  dummy;
-   
-   fifo_cascade #(.WIDTH(36), .SIZE(RXFIFOSIZE)) rx_fifo36
-     (.clk(fifo_clk), .reset(fifo_rst), .clear(clear_rx),
-      .datain(rx_data), .src_rdy_i(rx_src_rdy), .dst_rdy_o(rx_dst_rdy),
-      .dataout(rx36_data), .src_rdy_o(rx36_src_rdy), .dst_rdy_i(rx36_dst_rdy));
-
-   fifo36_to_fifo19 #(.LE(1)) f36_to_f19   // Little endian because ARM is LE
-     (.clk(fifo_clk), .reset(fifo_rst), .clear(clear_rx),
-      .f36_datain(rx36_data), .f36_src_rdy_i(rx36_src_rdy), .f36_dst_rdy_o(rx36_dst_rdy),
-      .f19_dataout({dummy,rx18_data}), .f19_src_rdy_o(rx18_src_rdy), .f19_dst_rdy_i(rx18_dst_rdy) );
-
-   fifo_cascade #(.WIDTH(18), .SIZE(12)) rx_fifo
-     (.clk(fifo_clk), .reset(fifo_rst), .clear(clear_rx),
-      .datain(rx18_data), .src_rdy_i(rx18_src_rdy), .dst_rdy_o(rx18_dst_rdy), .space(rx_fifo_space),
-      .dataout(rx18b_data), .src_rdy_o(rx18b_src_rdy), .dst_rdy_i(rx18b_dst_rdy), .occupied());
-
-   fifo_to_gpmc_async fifo_to_gpmc_async
-     (.clk(fifo_clk), .reset(fifo_rst), .clear(clear_rx),
-      .data_i(rx18b_data), .src_rdy_i(rx18b_src_rdy), .dst_rdy_o(rx18b_dst_rdy),
-      .EM_D(EM_D_fifo), .EM_NCS(EM_NCS4), .EM_NOE(EM_NOE),
-      .frame_len(rx_frame_len) );
-
-   wire [31:0] 	pkt_count;
-   
-   fifo_watcher fifo_watcher
-     (.clk(fifo_clk), .reset(fifo_rst), .clear(clear_rx),
-      .src_rdy1(rx18_src_rdy), .dst_rdy1(rx18_dst_rdy), .sof1(rx18_data[16]), .eof1(rx18_data[17]),
-      .src_rdy2(rx18b_src_rdy), .dst_rdy2(rx18b_dst_rdy), .sof2(rx18b_data[16]), .eof2(rx18b_data[17]),
-      .have_packet(rx_have_data), .length(rx_frame_len), .bus_error(bus_error_rx),
-      .debug(pkt_count));
-
-   // ////////////////////////////////////////////
-   // Control path on CS6
-   
-   gpmc_wb gpmc_wb
-     (.EM_CLK(EM_CLK), .EM_D_in(EM_D), .EM_D_out(EM_D_wb), .EM_A(EM_A), .EM_NBE(EM_NBE),
-      .EM_NCS(EM_NCS6), .EM_NWE(EM_NWE), .EM_NOE(EM_NOE),
-      .wb_clk(wb_clk), .wb_rst(wb_rst),
-      .wb_adr_o(wb_adr_o), .wb_dat_mosi(wb_dat_mosi), .wb_dat_miso(wb_dat_miso),
-      .wb_sel_o(wb_sel_o), .wb_cyc_o(wb_cyc_o), .wb_stb_o(wb_stb_o), .wb_we_o(wb_we_o),
-      .wb_ack_i(wb_ack_i) );
-   
-//      assign debug = pkt_count;
-
-   // ////////////////////////////////////////////
-   // Test support, traffic generator, loopback, etc.
-
-   // RX side muxes test data into the same stream
-   wire [35:0] 	timedrx_data, loopbackrx_data, testrx_data;
-   wire [35:0] 	timedtx_data, loopbacktx_data, testtx_data;
-   wire 	timedrx_src_rdy, timedrx_dst_rdy, loopbackrx_src_rdy, loopbackrx_dst_rdy,
-		testrx_src_rdy, testrx_dst_rdy;
-   wire 	timedtx_src_rdy, timedtx_dst_rdy, loopbacktx_src_rdy, loopbacktx_dst_rdy,
-		testtx_src_rdy, testtx_dst_rdy;
-   wire 	timedrx_src_rdy_int, timedrx_dst_rdy_int, timedtx_src_rdy_int, timedtx_dst_rdy_int;
-
-   wire [31:0] 	total, crc_err, seq_err, len_err;
-   wire 	sel_testtx = test_ctrl[0];
-   wire 	sel_loopbacktx = test_ctrl[1];
-   wire 	pkt_src_enable = test_ctrl[2];
-   wire 	pkt_sink_enable = test_ctrl[3];
-   
-   fifo36_mux rx_test_mux_lvl_1
-     (.clk(fifo_clk), .reset(fifo_rst), .clear(clear_rx),
-      .data0_i(timedrx_data), .src0_rdy_i(timedrx_src_rdy), .dst0_rdy_o(timedrx_dst_rdy),
-      .data1_i(loopbackrx_data), .src1_rdy_i(loopbackrx_src_rdy), .dst1_rdy_o(loopbackrx_dst_rdy),
-      .data_o(testrx_data), .src_rdy_o(testrx_src_rdy), .dst_rdy_i(testrx_dst_rdy));
-   
-   fifo36_mux rx_test_mux_lvl_2
-     (.clk(fifo_clk), .reset(fifo_rst), .clear(clear_rx),
-      .data0_i(testrx_data), .src0_rdy_i(testrx_src_rdy), .dst0_rdy_o(testrx_dst_rdy),
-      .data1_i(rx_data_i), .src1_rdy_i(rx_src_rdy_i), .dst1_rdy_o(rx_dst_rdy_o),
-      .data_o(rx_data), .src_rdy_o(rx_src_rdy), .dst_rdy_i(rx_dst_rdy));
-   
-   fifo_short #(.WIDTH(36)) loopback_fifo
-     (.clk(fifo_clk), .reset(fifo_rst), .clear(clear_tx | clear_rx),
-      .datain(loopbacktx_data), .src_rdy_i(loopbacktx_src_rdy), .dst_rdy_o(loopbacktx_dst_rdy),
-      .dataout(loopbackrx_data), .src_rdy_o(loopbackrx_src_rdy), .dst_rdy_i(loopbackrx_dst_rdy));
-   
-   // Crossbar used as a demux for switching TX stream to main DSP or to test logic
-   crossbar36 tx_crossbar_lvl_1
-     (.clk(fifo_clk), .reset(fifo_rst), .clear(clear_tx),
-      .cross(sel_testtx),
-      .data0_i(tx_data), .src0_rdy_i(tx_src_rdy), .dst0_rdy_o(tx_dst_rdy),
-      .data1_i(tx_data), .src1_rdy_i(1'b0), .dst1_rdy_o(),  // No 2nd input
-      .data0_o(tx_data_o), .src0_rdy_o(tx_src_rdy_o), .dst0_rdy_i(tx_dst_rdy_i),
-      .data1_o(testtx_data), .src1_rdy_o(testtx_src_rdy), .dst1_rdy_i(testtx_dst_rdy) );
-   
-   crossbar36 tx_crossbar_lvl_2
-     (.clk(fifo_clk), .reset(fifo_rst), .clear(clear_tx),
-      .cross(sel_loopbacktx),
-      .data0_i(testtx_data), .src0_rdy_i(testtx_src_rdy), .dst0_rdy_o(testtx_dst_rdy),
-      .data1_i(testtx_data), .src1_rdy_i(1'b0), .dst1_rdy_o(),  // No 2nd input
-      .data0_o(timedtx_data), .src0_rdy_o(timedtx_src_rdy), .dst0_rdy_i(timedtx_dst_rdy),
-      .data1_o(loopbacktx_data), .src1_rdy_o(loopbacktx_src_rdy), .dst1_rdy_i(loopbacktx_dst_rdy) );
-   
-   // Fixed rate TX traffic consumer
-   fifo_pacer tx_pacer
-     (.clk(fifo_clk), .reset(fifo_rst), .rate(test_rate), .enable(pkt_sink_enable),
-      .src1_rdy_i(timedtx_src_rdy), .dst1_rdy_o(timedtx_dst_rdy),
-      .src2_rdy_o(timedtx_src_rdy_int), .dst2_rdy_i(timedtx_dst_rdy_int),
-      .underrun(tx_underrun), .overrun());
-
-   packet_verifier32 pktver32
-     (.clk(fifo_clk), .reset(fifo_rst), .clear(clear_tx),
-      .data_i(timedtx_data), .src_rdy_i(timedtx_src_rdy_int), .dst_rdy_o(timedtx_dst_rdy_int),
-      .total(total), .crc_err(crc_err), .seq_err(seq_err), .len_err(len_err));
-
-   // Fixed rate RX traffic generator
-   packet_generator32 pktgen32
-     (.clk(fifo_clk), .reset(fifo_rst), .clear(clear_rx),
-      .header({len_err,seq_err,crc_err,total}),
-      .data_o(timedrx_data), .src_rdy_o(timedrx_src_rdy_int), .dst_rdy_i(timedrx_dst_rdy_int));
-
-   fifo_pacer rx_pacer
-     (.clk(fifo_clk), .reset(fifo_rst), .rate(test_rate), .enable(pkt_src_enable),
-      .src1_rdy_i(timedrx_src_rdy_int), .dst1_rdy_o(timedrx_dst_rdy_int),
-      .src2_rdy_o(timedrx_src_rdy), .dst2_rdy_i(timedrx_dst_rdy),
-      .underrun(), .overrun(rx_overrun));
-
-   // FIXME -- hook up crossbar controls
-   // // FIXME -- collect error stats
-   // FIXME -- set rates and enables on pacers
-   // FIXME -- make sure packet completes before we shutoff
-   // FIXME -- handle overrun and underrun
-
-wire [0:17] dummy18;
-
-assign debug = {8'd0,
-		test_rate,
-		pkt_src_enable, pkt_sink_enable, timedrx_src_rdy_int, timedrx_dst_rdy_int,
-		timedrx_src_rdy, timedrx_dst_rdy,
-		testrx_src_rdy, testrx_dst_rdy,
-		rx_src_rdy, rx_dst_rdy,
-		rx36_src_rdy, rx36_dst_rdy,
-		rx18_src_rdy, rx18_dst_rdy,
-		rx18b_src_rdy, rx18b_dst_rdy};
-
-endmodule // gpmc_async
diff --git a/usrp2/gpmc/gpmc_sync.v b/usrp2/gpmc/gpmc_sync.v
deleted file mode 100644
index ba7251c8d..000000000
--- a/usrp2/gpmc/gpmc_sync.v
+++ /dev/null
@@ -1,125 +0,0 @@
-//
-// Copyright 2011 Ettus Research LLC
-//
-// This program is free software: you can redistribute it and/or modify
-// it under the terms of the GNU General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-//
-// This program is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU General Public License for more details.
-//
-// You should have received a copy of the GNU General Public License
-// along with this program.  If not, see <http://www.gnu.org/licenses/>.
-//
-
-//////////////////////////////////////////////////////////////////////////////////
-
-module gpmc_sync
-  (// GPMC signals
-   input arst,
-   input EM_CLK, inout [15:0] EM_D, input [10:1] EM_A, input [1:0] EM_NBE,
-   input EM_WAIT0, input EM_NCS4, input EM_NCS6, input EM_NWE, input EM_NOE,
-   
-   // GPIOs for FIFO signalling
-   output rx_have_data, output tx_have_space, output bus_error, input bus_reset,
-   
-   // Wishbone signals
-   input wb_clk, input wb_rst,
-   output [10:0] wb_adr_o, output [15:0] wb_dat_mosi, input [15:0] wb_dat_miso,
-   output [1:0] wb_sel_o, output wb_cyc_o, output wb_stb_o, output wb_we_o, input wb_ack_i,
-
-   // FIFO interface
-   input fifo_clk, input fifo_rst,
-   output [35:0] tx_data_o, output tx_src_rdy_o, input tx_dst_rdy_i,
-   input [35:0] rx_data_i, input rx_src_rdy_i, output rx_dst_rdy_o,
-
-   output [31:0] debug
-   );
-
-   wire 	EM_output_enable = (~EM_NOE & (~EM_NCS4 | ~EM_NCS6));
-   wire [15:0] 	EM_D_fifo;
-   wire [15:0] 	EM_D_wb;
-
-   assign EM_D = ~EM_output_enable ? 16'bz : ~EM_NCS4 ? EM_D_fifo : EM_D_wb;
-
-   wire 	bus_error_tx, bus_error_rx;
-   assign bus_error = bus_error_tx | bus_error_rx;
-   
-   // CS4 is RAM_2PORT for DATA PATH (high-speed data)
-   //    Writes go into one RAM, reads come from the other
-   // CS6 is for CONTROL PATH (wishbone)
-
-   // ////////////////////////////////////////////
-   // TX Data Path
-
-   wire [17:0] 	tx18_data, tx18b_data;
-   wire 	tx18_src_rdy, tx18_dst_rdy, tx18b_src_rdy, tx18b_dst_rdy;
-   wire [15:0] 	tx_fifo_space, tx_frame_len;
-   
-   assign tx_frame_len = 10;
-   
-   gpmc_to_fifo_sync gpmc_to_fifo_sync
-     (.arst(arst),
-      .EM_CLK(EM_CLK), .EM_D(EM_D), .EM_NBE(EM_NBE), .EM_NCS(EM_NCS4), .EM_NWE(EM_NWE),
-      .data_o(tx18_data), .src_rdy_o(tx18_src_rdy), .dst_rdy_i(tx18_dst_rdy),
-      .frame_len(tx_frame_len), .fifo_space(tx_fifo_space), .fifo_ready(tx_have_space),
-      .bus_error(bus_error_tx) );
-   
-   fifo_2clock_cascade #(.WIDTH(18), .SIZE(4)) tx_fifo
-     (.wclk(EM_CLK), .datain(tx18_data), 
-      .src_rdy_i(tx18_src_rdy), .dst_rdy_o(tx18_dst_rdy), .space(tx_fifo_space),
-      .rclk(fifo_clk), .dataout(tx18b_data), 
-      .src_rdy_o(tx18b_src_rdy), .dst_rdy_i(tx18b_dst_rdy), .occupied(), .arst(arst));
-
-   fifo19_to_fifo36 #(.LE(1)) f19_to_f36   // Little endian because ARM is LE
-     (.clk(fifo_clk), .reset(fifo_rst), .clear(0),
-      .f19_datain({1'b0,tx18b_data}), .f19_src_rdy_i(tx18b_src_rdy), .f19_dst_rdy_o(tx18b_dst_rdy),
-      .f36_dataout(tx_data_o), .f36_src_rdy_o(tx_src_rdy_o), .f36_dst_rdy_i(tx_dst_rdy_i));
-   
-   // ////////////////////////////////////////////
-   // RX Data Path
-
-   wire [17:0] 	rx18_data, rx18b_data;
-   wire 	rx18_src_rdy, rx18_dst_rdy, rx18b_src_rdy, rx18b_dst_rdy;
-   wire [15:0] 	rx_fifo_space, rx_frame_len;
-   wire 	dummy;
-   
-   fifo36_to_fifo19 #(.LE(1)) f36_to_f19   // Little endian because ARM is LE
-     (.clk(fifo_clk), .reset(fifo_rst), .clear(0),
-      .f36_datain(rx_data_i), .f36_src_rdy_i(rx_src_rdy_i), .f36_dst_rdy_o(rx_dst_rdy_o),
-      .f19_dataout({dummy,rx18_data}), .f19_src_rdy_o(rx18_src_rdy), .f19_dst_rdy_i(rx18_dst_rdy) );
-
-   fifo_2clock_cascade #(.WIDTH(18), .SIZE(10)) rx_fifo
-     (.wclk(fifo_clk), .datain(rx18_data), 
-      .src_rdy_i(rx18_src_rdy), .dst_rdy_o(rx18_dst_rdy), .space(rx_fifo_space),
-      .rclk(EM_CLK), .dataout(rx18b_data), 
-      .src_rdy_o(rx18b_src_rdy), .dst_rdy_i(rx18b_dst_rdy), .occupied(), .arst(arst));
-
-   fifo_to_gpmc_sync fifo_to_gpmc_sync
-     (.arst(arst),
-      .data_i(rx18b_data), .src_rdy_i(rx18b_src_rdy), .dst_rdy_o(rx18b_dst_rdy),
-      .EM_CLK(EM_CLK), .EM_D(EM_D_fifo), .EM_NCS(EM_NCS4), .EM_NOE(EM_NOE),
-      .fifo_ready(rx_have_data) );
-
-   fifo_watcher fifo_watcher
-     (.clk(fifo_clk), .reset(fifo_rst), .clear(0),
-      .src_rdy(rx18_src_rdy), .dst_rdy(rx18_dst_rdy), .sof(rx18_data[16]), .eof(rx18_data[17]),
-      .have_packet(), .length(), .next() );
-   
-   // ////////////////////////////////////////////
-   // Control path on CS6
-   
-   gpmc_wb gpmc_wb
-     (.EM_CLK(EM_CLK), .EM_D_in(EM_D), .EM_D_out(EM_D_wb), .EM_A(EM_A), .EM_NBE(EM_NBE),
-      .EM_NCS(EM_NCS6), .EM_NWE(EM_NWE), .EM_NOE(EM_NOE),
-      .wb_clk(wb_clk), .wb_rst(wb_rst),
-      .wb_adr_o(wb_adr_o), .wb_dat_mosi(wb_dat_mosi), .wb_dat_miso(wb_dat_miso),
-      .wb_sel_o(wb_sel_o), .wb_cyc_o(wb_cyc_o), .wb_stb_o(wb_stb_o), .wb_we_o(wb_we_o),
-      .wb_ack_i(wb_ack_i) );
-   
-      assign debug = 0;
-   
-endmodule // gpmc_sync
diff --git a/usrp2/gpmc/gpmc_to_fifo.v b/usrp2/gpmc/gpmc_to_fifo.v
new file mode 100644
index 000000000..4aa55953a
--- /dev/null
+++ b/usrp2/gpmc/gpmc_to_fifo.v
@@ -0,0 +1,157 @@
+//
+// Copyright 2011 Ettus Research LLC
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+//
+
+////////////////////////////////////////////////////////////////////////
+// GPMC to FIFO
+//
+// Reads frames from BRAM pages and writes them into FIFO interface.
+// The GPMC is asynchronously alerted when a BRAM page is available.
+//
+// EM_CLK:
+// A GPMC read transaction consists of one EM_CLK cycle (idle low).
+//
+// EM_WE:
+// Write enable is actually the combination of ~NWE & ~NCS.
+// The write enable is active for the entire transaction.
+//
+// EM_D:
+// Data is set on the rising edge and written into BRAM on the falling edge.
+//
+// EM_A:
+// Address is set on the rising edge and read by BRAM on the falling edge.
+////////////////////////////////////////////////////////////////////////
+
+module gpmc_to_fifo
+  #(parameter PTR_WIDTH = 2, parameter ADDR_WIDTH = 10)
+  (input [15:0] EM_D, input [ADDR_WIDTH:1] EM_A, input EM_CLK, input EM_WE,
+   input clk, input reset, input clear, input arst,
+   output [17:0] data_o, output src_rdy_o, input dst_rdy_i,
+   output reg have_space);
+
+    //states for the GPMC side of things
+    wire [17:0] data_i;
+    reg gpmc_state;
+    reg [ADDR_WIDTH:1] last_addr;
+    reg [PTR_WIDTH:0] gpmc_ptr, next_gpmc_ptr;
+    localparam GPMC_STATE_START = 0;
+    localparam GPMC_STATE_FILL = 1;
+
+    //states for the FIFO side of things
+    reg fifo_state;
+    reg [ADDR_WIDTH-1:0] counter;
+    reg [PTR_WIDTH:0] fifo_ptr;
+    localparam FIFO_STATE_CLAIM = 0;
+    localparam FIFO_STATE_EMPTY = 1;
+
+    //------------------------------------------------------------------
+    // State machine to control the data from GPMC to BRAM
+    //------------------------------------------------------------------
+    always @(negedge EM_CLK or posedge arst) begin
+        if (arst) begin
+            gpmc_state <= GPMC_STATE_START;
+            gpmc_ptr <= 0;
+            next_gpmc_ptr <= 0;
+        end
+        else if (EM_WE) begin
+            case(gpmc_state)
+
+            GPMC_STATE_START: begin
+                if (EM_A == 0) begin
+                    gpmc_state <= GPMC_STATE_FILL;
+                    last_addr <= {EM_D[ADDR_WIDTH-2:0], 1'b0} - 1'b1;
+                    next_gpmc_ptr <= gpmc_ptr + 1;
+                end
+            end
+
+            GPMC_STATE_FILL: begin
+                if (data_i[17]) begin
+                    gpmc_state <= GPMC_STATE_START;
+                    gpmc_ptr <= next_gpmc_ptr;
+                end
+            end
+
+            endcase //gpmc_state
+        end //EM_WE
+    end //always
+
+    //------------------------------------------------------------------
+    // A block ram is available to empty when the pointers dont match.
+    //------------------------------------------------------------------
+    wire [PTR_WIDTH:0] safe_gpmc_ptr;
+    cross_clock_reader #(.WIDTH(PTR_WIDTH+1)) read_gpmc_ptr
+        (.clk(clk), .rst(reset | clear), .in(gpmc_ptr), .out(safe_gpmc_ptr));
+
+    wire bram_available_to_empty = safe_gpmc_ptr != fifo_ptr;
+
+    //------------------------------------------------------------------
+    // Glich free generation of have space signal:
+    // High when the fifo pointer has not caught up to the gpmc pointer.
+    //------------------------------------------------------------------
+    wire [PTR_WIDTH:0] safe_next_gpmc_ptr;
+    cross_clock_reader #(.WIDTH(PTR_WIDTH+1)) read_next_gpmc_ptr
+        (.clk(clk), .rst(reset | clear), .in(next_gpmc_ptr), .out(safe_next_gpmc_ptr));
+
+    always @(posedge clk)
+        if (reset | clear) have_space <= 0;
+        else               have_space <= (fifo_ptr ^ (1 << PTR_WIDTH)) != safe_next_gpmc_ptr;
+
+    //------------------------------------------------------------------
+    // State machine to control the data from BRAM to FIFO
+    //------------------------------------------------------------------
+    always @(posedge clk) begin
+        if (reset | clear) begin
+            fifo_state <= FIFO_STATE_CLAIM;
+            fifo_ptr <= 0;
+            counter <= 0;
+        end
+        else begin
+            case(fifo_state)
+
+            FIFO_STATE_CLAIM: begin
+                if (bram_available_to_empty) fifo_state <= FIFO_STATE_EMPTY;
+                counter <= 0;
+            end
+
+            FIFO_STATE_EMPTY: begin
+                if (src_rdy_o && dst_rdy_i && data_o[17]) begin
+                    fifo_state <= FIFO_STATE_CLAIM;
+                    fifo_ptr <= fifo_ptr + 1;
+                end
+                if (src_rdy_o && dst_rdy_i) begin
+                    counter <= counter + 1;
+                end
+            end
+
+            endcase //fifo_state
+        end
+    end //always
+
+    assign src_rdy_o = fifo_state == FIFO_STATE_EMPTY;
+
+    //assign data and frame bits to bram input
+    assign data_i[15:0] = EM_D;
+    assign data_i[16] = (gpmc_state == GPMC_STATE_START);
+    assign data_i[17] = (EM_A == last_addr);
+
+    //instantiate dual ported bram for async read + write
+    ram_2port #(.DWIDTH(18),.AWIDTH(PTR_WIDTH + ADDR_WIDTH)) async_fifo_bram
+     (.clka(~EM_CLK),.ena(1'b1),.wea(EM_WE),
+      .addra({gpmc_ptr[PTR_WIDTH-1:0], EM_A}),.dia(data_i),.doa(),
+      .clkb(~clk),.enb(1'b1),.web(1'b0),
+      .addrb({fifo_ptr[PTR_WIDTH-1:0], counter}),.dib(18'h3ffff),.dob(data_o));
+
+endmodule // gpmc_to_fifo
diff --git a/usrp2/gpmc/gpmc_to_fifo_async.v b/usrp2/gpmc/gpmc_to_fifo_async.v
deleted file mode 100644
index aa93e52af..000000000
--- a/usrp2/gpmc/gpmc_to_fifo_async.v
+++ /dev/null
@@ -1,85 +0,0 @@
-//
-// Copyright 2011 Ettus Research LLC
-//
-// This program is free software: you can redistribute it and/or modify
-// it under the terms of the GNU General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-//
-// This program is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU General Public License for more details.
-//
-// You should have received a copy of the GNU General Public License
-// along with this program.  If not, see <http://www.gnu.org/licenses/>.
-//
-
-
-module gpmc_to_fifo_async
-  (input [15:0] EM_D, input [1:0] EM_NBE, input EM_NCS, input EM_NWE,
-
-   input fifo_clk, input fifo_rst, input clear,
-   output reg [17:0] data_o, output reg src_rdy_o, input dst_rdy_i,
-
-   input [15:0] frame_len, input [15:0] fifo_space, output reg fifo_ready,
-   output reg bus_error );
-
-   reg [15:0] counter;
-   // Synchronize the async control signals
-   reg [1:0] 	cs_del, we_del;
-   always @(posedge fifo_clk)
-     if(fifo_rst)
-       begin
-	  cs_del <= 2'b11;
-	  we_del <= 2'b11;
-       end
-     else
-       begin
-	  cs_del <= { cs_del[0], EM_NCS };
-	  we_del <= { we_del[0], EM_NWE };
-       end
-
-   wire do_write = (~cs_del[0] & (we_del == 2'b10));
-   wire first_write = (counter == 0);
-   wire last_write = ((counter+1) == frame_len);
-
-   always @(posedge fifo_clk)
-     if(do_write)
-       begin
-	  data_o[15:0] <= EM_D;
-	  data_o[16] <= first_write;
-	  data_o[17] <= last_write;
-	  //  no byte writes data_o[18] <= |EM_NBE;  // mark half full if either is not enabled  FIXME
-       end
-
-   always @(posedge fifo_clk)
-     if(fifo_rst | clear)
-       src_rdy_o <= 0;
-     else if(do_write)
-       src_rdy_o <= 1;
-     else
-       src_rdy_o <= 0;    // Assume it was taken
-
-   always @(posedge fifo_clk)
-     if(fifo_rst | clear)
-       counter <= 0;
-     else if(do_write)
-       if(last_write)
-	 counter <= 0;
-       else
-	 counter <= counter + 1;
-
-   always @(posedge fifo_clk)
-     if(fifo_rst | clear)
-       fifo_ready <= 0;
-     else
-       fifo_ready <= /* first_write & */ (fifo_space > 16'd1023);
-
-   always @(posedge fifo_clk)
-     if(fifo_rst | clear)
-       bus_error <= 0;
-     else if(src_rdy_o & ~dst_rdy_i)
-       bus_error <= 1;
-   
-endmodule // gpmc_to_fifo_async
diff --git a/usrp2/gpmc/gpmc_to_fifo_sync.v b/usrp2/gpmc/gpmc_to_fifo_sync.v
deleted file mode 100644
index 7ff7afdc2..000000000
--- a/usrp2/gpmc/gpmc_to_fifo_sync.v
+++ /dev/null
@@ -1,74 +0,0 @@
-//
-// Copyright 2011 Ettus Research LLC
-//
-// This program is free software: you can redistribute it and/or modify
-// it under the terms of the GNU General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-//
-// This program is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU General Public License for more details.
-//
-// You should have received a copy of the GNU General Public License
-// along with this program.  If not, see <http://www.gnu.org/licenses/>.
-//
-
-
-// Assumes a GPMC cycle with GPMC clock, as in the timing diagrams
-//   If a packet bigger or smaller than we are told is sent, behavior is undefined.
-//   If dst_rdy_i is low when we get data, behavior is undefined and we signal bus error.
-//   If there is a bus error, we should be reset
-
-module gpmc_to_fifo_sync
-  (input arst,
-   input EM_CLK, input [15:0] EM_D, input [1:0] EM_NBE,
-   input EM_NCS, input EM_NWE,
-   output reg [17:0] data_o, output reg src_rdy_o, input dst_rdy_i,
-   input [15:0] frame_len, input [15:0] fifo_space, output fifo_ready, 
-   output reg bus_error);
-   
-   reg [10:0] 	counter;
-   wire 	first_write = (counter == 0);
-   wire 	last_write = ((counter+1) == frame_len);
-   wire 	do_write = ~EM_NCS & ~EM_NWE;
-   
-   always @(posedge EM_CLK or posedge arst)
-     if(arst)
-       data_o <= 0;
-     else if(do_write)
-       begin
-	  data_o[15:0] <= EM_D;
-	  data_o[16] <= first_write;
-	  data_o[17] <= last_write;
-	  //  no byte writes data_o[18] <= |EM_NBE;  // mark half full if either is not enabled  FIXME
-       end
-
-   always @(posedge EM_CLK or posedge arst)
-     if(arst)
-       src_rdy_o <= 0;
-     else if(do_write & ~bus_error)  // Don't put junk in if there is a bus error
-       src_rdy_o <= 1;
-     else
-       src_rdy_o <= 0;    // Assume it was taken, ignore dst_rdy_i
-
-   always @(posedge EM_CLK or posedge arst)
-     if(arst)
-       counter <= 0;
-     else if(do_write)
-       if(last_write)
-	 counter <= 0;
-       else
-	 counter <= counter + 1;
-
-   assign fifo_ready = first_write & (fifo_space > frame_len);
-   
-   always @(posedge EM_CLK or posedge arst)
-     if(arst)
-       bus_error <= 0;
-     else if(src_rdy_o & ~dst_rdy_i)
-       bus_error <= 1;
-   // must be reset to make the error go away
-
-endmodule // gpmc_to_fifo_sync
diff --git a/usrp2/gpmc/gpmc_wb.v b/usrp2/gpmc/gpmc_wb.v
index 645201ef7..4d368ca94 100644
--- a/usrp2/gpmc/gpmc_wb.v
+++ b/usrp2/gpmc/gpmc_wb.v
@@ -19,7 +19,7 @@
 
 module gpmc_wb
   (input EM_CLK, input [15:0] EM_D_in, output [15:0] EM_D_out, input [10:1] EM_A, input [1:0] EM_NBE,
-   input EM_NCS, input EM_NWE, input EM_NOE,
+   input EM_WE, input EM_OE,
 
    input wb_clk, input wb_rst,
    output reg [10:0] wb_adr_o, output reg [15:0] wb_dat_mosi, input [15:0] wb_dat_miso,
@@ -27,25 +27,31 @@ module gpmc_wb
    
    // ////////////////////////////////////////////
    // Control Path, Wishbone bus bridge (wb master)
-   reg [1:0] 	cs_del, we_del, oe_del;
+   reg [1:0] we_del, oe_del;
 
    // Synchronize the async control signals
    always @(posedge wb_clk)
-     begin
-	cs_del <= { cs_del[0], EM_NCS };
-	we_del <= { we_del[0], EM_NWE };
-	oe_del <= { oe_del[0], EM_NOE };
+     if (wb_rst) begin
+        we_del <= 2'b0;
+        oe_del <= 2'b0;
      end
+     else begin
+        we_del <= { we_del[0], EM_WE };
+        oe_del <= { oe_del[0], EM_OE };
+     end
+
+    wire writing = we_del == 2'b01;
+    wire reading = oe_del == 2'b01;
 
    always @(posedge wb_clk)
-     if(cs_del == 2'b10)  // Falling Edge
+     if(writing || reading)
        wb_adr_o <= { EM_A, 1'b0 };
 
    always @(posedge wb_clk)
-     if(we_del == 2'b10)  // Falling Edge
+     if(writing)
        begin
-	  wb_dat_mosi <= EM_D_in;
-	  wb_sel_o <= ~EM_NBE;
+          wb_dat_mosi <= EM_D_in;
+          wb_sel_o <= ~EM_NBE;
        end
 
    reg [15:0] EM_D_hold;
@@ -59,14 +65,13 @@ module gpmc_wb
    assign wb_cyc_o = wb_stb_o;
 
    always @(posedge wb_clk)
-     if(~cs_del[0] & (we_del == 2'b10) )
+     if(writing)
        wb_we_o <= 1;
      else if(wb_ack_i)  // Turn off we when done.  Could also use we_del[0], others...
        wb_we_o <= 0;
 
-   // FIXME should this look at cs_del[1]?
    always @(posedge wb_clk)
-     if(~cs_del[0] & ((we_del == 2'b10) | (oe_del == 2'b10)))
+     if(writing || reading)
        wb_stb_o <= 1;
      else if(wb_ack_i)
        wb_stb_o <= 0;
diff --git a/usrp2/gpmc/make_timing_diag b/usrp2/gpmc/make_timing_diag
deleted file mode 100755
index 03166ad35..000000000
--- a/usrp2/gpmc/make_timing_diag
+++ /dev/null
@@ -1,6 +0,0 @@
-#!/bin/sh
-drawtiming -o single_data_write.gif single_data_write.txt
-drawtiming -o single_data_read.gif single_data_read.txt
-drawtiming -o burst_data_write.gif burst_data_write.txt
-#drawtiming -o burst_data_read.gif burst_data_read.txt
-
diff --git a/usrp2/gpmc/ram_to_fifo.v b/usrp2/gpmc/ram_to_fifo.v
deleted file mode 100644
index 958c88b0f..000000000
--- a/usrp2/gpmc/ram_to_fifo.v
+++ /dev/null
@@ -1,63 +0,0 @@
-//
-// Copyright 2011 Ettus Research LLC
-//
-// This program is free software: you can redistribute it and/or modify
-// it under the terms of the GNU General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-//
-// This program is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU General Public License for more details.
-//
-// You should have received a copy of the GNU General Public License
-// along with this program.  If not, see <http://www.gnu.org/licenses/>.
-//
-
-
-
-module ram_to_fifo
-  (input clk, input reset,
-   input [10:0] read_length,  // From the dbsm (?)
-   output read_en, output reg [8:0] read_addr, input [31:0] read_data, input read_ready, output read_done,
-   output [35:0] data_o, output src_rdy_o, input dst_rdy_i);
-
-   // read_length/2 = number of 32 bit lines, numbered 0 through read_length/2-1
-   wire [8:0] 	 last_line = (read_length[10:1]-1); 
-
-   reg 		 read_phase, sop;
-
-   assign read_en = (read_phase == 0) | dst_rdy_i;
-   assign src_rdy_o = (read_phase == 1);
-   
-   always @(posedge clk)
-     if(reset)
-       begin
-	  read_addr <= 0;
-	  read_phase <= 0;
-	  sop <= 1;
-       end
-     else
-       if(read_phase == 0)
-	 begin
-	    read_addr <= read_ready;
-	    read_phase <= read_ready;
-	 end
-       else if(dst_rdy_i)
-	 begin
-	    sop <= 0;
-	    if(read_addr == last_line)
-	      begin
-		 read_addr <= 0;
-		 read_phase <= 0;
-	      end
-	    else
-	      read_addr <= read_addr + 1;
-	 end
-   
-   assign read_done = (read_phase == 1) & (read_addr == last_line) & dst_rdy_i;
-   wire eop = (read_addr == last_line);
-   assign data_o = { 2'b00, eop, sop, read_data };
-   
-endmodule // ram_to_fifo
diff --git a/usrp2/gpmc/single_data_read.txt b/usrp2/gpmc/single_data_read.txt
deleted file mode 100644
index 1dc0e3a78..000000000
--- a/usrp2/gpmc/single_data_read.txt
+++ /dev/null
@@ -1,12 +0,0 @@
-# OMAP writes to FPGA
-# initialize the signals
-CLK=0,nWE=1,nCS=1,nOE=1,DATA=Z.
-CLK=1.
-CLK=0,nOE=0,nCS=0,DATA=RD_DATA.
-CLK=1.
-CLK=0.
-CLK=1.
-CLK=0,nOE=1,nCS=1,DATA=Z.
-CLK=1.
-
-
diff --git a/usrp2/gpmc/single_data_write.txt b/usrp2/gpmc/single_data_write.txt
deleted file mode 100644
index 287e3e2c1..000000000
--- a/usrp2/gpmc/single_data_write.txt
+++ /dev/null
@@ -1,10 +0,0 @@
-# OMAP writes to FPGA
-# initialize the signals
-CLK=0,nWE=1,nCS=1,nOE=1,DATA=Z.
-CLK=1.
-CLK=0,nWE=0,nCS=0,DATA=WR_DATA.
-CLK=1.
-CLK=0,nWE=1,nCS=1,DATA=Z.
-CLK=1.
-
-
diff --git a/usrp2/top/E1x0/timing.ucf b/usrp2/top/E1x0/timing.ucf
index 8df28c9d3..f94685438 100644
--- a/usrp2/top/E1x0/timing.ucf
+++ b/usrp2/top/E1x0/timing.ucf
@@ -2,8 +2,22 @@
 NET "CLK_FPGA_P" TNM_NET = "CLK_FPGA_P";
 TIMESPEC "TS_clk_fpga_p" = PERIOD "CLK_FPGA_P" 15625 ps HIGH 50 %;
 
+NET "EM_CLK" TNM_NET = "EM_CLK";
+TIMESPEC "TS_em_clk" = PERIOD "EM_CLK" 12048 ps HIGH 50 %;
 
+#constrain GPMC IO
+NET "EM_D<*>" MAXDELAY = 5 ns;
+NET "EM_A<*>" MAXDELAY = 5 ns;
+NET "EM_NBE<*>" MAXDELAY = 5 ns;
+NET "EM_NCS4" MAXDELAY = 5 ns;
+NET "EM_NCS6" MAXDELAY = 5 ns;
+NET "EM_NWE" MAXDELAY = 5 ns;
+NET "EM_NOE" MAXDELAY = 5 ns;
 
+#constrain interrupt lines
+NET "overo_gpio144" MAXDELAY = 5 ns; #have space
+NET "overo_gpio146" MAXDELAY = 5 ns; #have data
+NET "overo_gpio147" MAXDELAY = 5 ns; #have msg/aux spi miso
 
 #NET "adc_a<*>" TNM_NET = ADC_DATA_GRP;
 #NET "adc_b<*>" TNM_NET = ADC_DATA_GRP;
diff --git a/usrp2/top/E1x0/u1e.v b/usrp2/top/E1x0/u1e.v
index dbd6173f3..ff2e08394 100644
--- a/usrp2/top/E1x0/u1e.v
+++ b/usrp2/top/E1x0/u1e.v
@@ -53,32 +53,10 @@ module u1e
 
    // /////////////////////////////////////////////////////////////////////////
    // Clocking
-   wire  clk_fpga, clk_fpga_in;
-   
+   wire  clk_fpga;
+
    IBUFGDS #(.IOSTANDARD("LVDS_33"), .DIFF_TERM("TRUE")) 
-   clk_fpga_pin (.O(clk_fpga_in),.I(CLK_FPGA_P),.IB(CLK_FPGA_N));
-
-   wire  clk_2x, dcm_rst, dcm_locked, clk_fb;
-   DCM #(.CLK_FEEDBACK ( "1X" ),
-	 .CLKDV_DIVIDE ( 2 ),
-	 .CLKFX_DIVIDE ( 2 ),
-	 .CLKFX_MULTIPLY ( 2 ),
-	 .CLKIN_DIVIDE_BY_2 ( "FALSE" ),
-	 .CLKIN_PERIOD ( 15.625 ),
-	 .CLKOUT_PHASE_SHIFT ( "NONE" ),
-	 .DESKEW_ADJUST ( "SYSTEM_SYNCHRONOUS" ),
-	 .DFS_FREQUENCY_MODE ( "LOW" ),
-	 .DLL_FREQUENCY_MODE ( "LOW" ),
-	 .DUTY_CYCLE_CORRECTION ( "TRUE" ),
-	 .FACTORY_JF ( 16'h8080 ),
-	 .PHASE_SHIFT ( 0 ),
-	 .STARTUP_WAIT ( "FALSE" ))
-   clk_doubler (.CLKFB(clk_fb), .CLKIN(clk_fpga_in), .RST(dcm_rst), 
-                .DSSEN(0), .PSCLK(0), .PSEN(0), .PSINCDEC(0), .PSDONE(), 
-		.CLKDV(), .CLKFX(), .CLKFX180(), 
-                .CLK2X(), .CLK2X180(), 
-                .CLK0(clk_fb), .CLK90(clk_fpga), .CLK180(), .CLK270(), 
-                .LOCKED(dcm_locked), .STATUS());
+   clk_fpga_pin (.O(clk_fpga),.I(CLK_FPGA_P),.IB(CLK_FPGA_N));
 
    // /////////////////////////////////////////////////////////////////////////
    // SPI
diff --git a/usrp2/top/E1x0/u1e_core.v b/usrp2/top/E1x0/u1e_core.v
index 8cd51fc10..20dd98a36 100644
--- a/usrp2/top/E1x0/u1e_core.v
+++ b/usrp2/top/E1x0/u1e_core.v
@@ -36,7 +36,7 @@ module u1e_core
    output [13:0] tx_i, output [13:0] tx_q, 
    input [11:0] rx_i, input [11:0] rx_q, 
    
-   input pps_in, output proc_int
+   input pps_in, output reg proc_int
    );
 
    localparam TXFIFOSIZE = 13;
@@ -60,7 +60,7 @@ module u1e_core
    localparam SR_CLEAR_TX_FIFO = 62; // 1 reg
    localparam SR_GLOBAL_RESET = 63;  // 1 reg
 
-   wire [7:0]	COMPAT_NUM = 8'd5;
+   wire [7:0]	COMPAT_NUM = 8'd6;
    
    wire 	wb_clk = clk_fpga;
    wire 	wb_rst, global_reset;
@@ -102,10 +102,7 @@ module u1e_core
    wire [35:0] 	 tx_data, rx_data, tx_err_data;
    wire 	 tx_src_rdy, tx_dst_rdy, rx_src_rdy, rx_dst_rdy, 
 		 tx_err_src_rdy, tx_err_dst_rdy;
-   reg [15:0] 	 tx_frame_len;
-   wire [15:0] 	 rx_frame_len;
 
-   wire 	 bus_error;
    wire 	 clear_tx, clear_rx;
    
    setting_reg #(.my_addr(SR_CLEAR_RX_FIFO), .width(1)) sr_clear_rx
@@ -116,14 +113,13 @@ module u1e_core
      (.clk(wb_clk),.rst(wb_rst),.strobe(set_stb),.addr(set_addr),
       .in(set_data),.out(),.changed(clear_tx));
 
-   gpmc_async #(.TXFIFOSIZE(TXFIFOSIZE), .RXFIFOSIZE(RXFIFOSIZE))
+   gpmc #(.TXFIFOSIZE(TXFIFOSIZE), .RXFIFOSIZE(RXFIFOSIZE))
    gpmc (.arst(wb_rst),
 	 .EM_CLK(EM_CLK), .EM_D(EM_D), .EM_A(EM_A), .EM_NBE(EM_NBE),
 	 .EM_WAIT0(EM_WAIT0), .EM_NCS4(EM_NCS4), .EM_NCS6(EM_NCS6), .EM_NWE(EM_NWE), 
 	 .EM_NOE(EM_NOE),
 	 
 	 .rx_have_data(rx_have_data), .tx_have_space(tx_have_space),
-	 .bus_error(bus_error), .bus_reset(0),
 	 
 	 .wb_clk(wb_clk), .wb_rst(wb_rst),
 	 .wb_adr_o(m0_adr), .wb_dat_mosi(m0_dat_mosi), .wb_dat_miso(m0_dat_miso),
@@ -133,8 +129,7 @@ module u1e_core
 	 .fifo_clk(wb_clk), .fifo_rst(wb_rst), .clear_tx(clear_tx), .clear_rx(clear_rx),
 	 .tx_data_o(tx_data), .tx_src_rdy_o(tx_src_rdy), .tx_dst_rdy_i(tx_dst_rdy),
 	 .rx_data_i(rx_data), .rx_src_rdy_i(rx_src_rdy), .rx_dst_rdy_o(rx_dst_rdy),
-	 
-	 .tx_frame_len(tx_frame_len), .rx_frame_len(rx_frame_len),
+
 	 .tx_underrun(tx_underrun_gpmc), .rx_overrun(rx_overrun_gpmc),
 
 	 .test_rate(test_rate), .test_ctrl(test_ctrl),
@@ -313,8 +308,6 @@ module u1e_core
    localparam REG_CGEN_CTRL = 7'd4;    // out
    localparam REG_CGEN_ST = 7'd6;      // in
    localparam REG_TEST = 7'd8;         // out
-   localparam REG_RX_FRAMELEN = 7'd10; // in
-   localparam REG_TX_FRAMELEN = 7'd12; // out
    localparam REG_XFER_RATE = 7'd14;   // out
    localparam REG_COMPAT = 7'd16;      // in
    
@@ -324,7 +317,6 @@ module u1e_core
 	  reg_leds <= 0;
 	  reg_cgen_ctrl <= 2'b11;
 	  reg_test <= 0;
-	  tx_frame_len <= 0;
 	  xfer_rate <= 0;
        end
      else
@@ -336,8 +328,6 @@ module u1e_core
 	     reg_cgen_ctrl <= s0_dat_mosi;
 	   REG_TEST :
 	     reg_test <= s0_dat_mosi;
-	   REG_TX_FRAMELEN :
-	     tx_frame_len <= s0_dat_mosi;
 	   REG_XFER_RATE :
 	     xfer_rate <= s0_dat_mosi;
 	 endcase // case (s0_adr[6:0])
@@ -352,7 +342,6 @@ module u1e_core
 			(s0_adr[6:0] == REG_CGEN_CTRL) ? reg_cgen_ctrl :
 			(s0_adr[6:0] == REG_CGEN_ST) ? {13'b0,cgen_st_status,cgen_st_ld,cgen_st_refmon} :
 			(s0_adr[6:0] == REG_TEST) ? reg_test :
-			(s0_adr[6:0] == REG_RX_FRAMELEN) ? rx_frame_len :
 			(s0_adr[6:0] == REG_COMPAT) ? { 8'd0, COMPAT_NUM } :
 			16'hBEEF;
    
@@ -433,7 +422,7 @@ module u1e_core
         // Wishbone interface to RAM
         .wb_clk_i(wb_clk), .wb_rst_i(wb_rst),
         .wb_we_i(s5_we),   .wb_stb_i(s5_stb),
-        .wb_adr_i(s5_adr), .wb_dat_i({16'b0, s5_dat_mosi}),
+        .wb_adr_i({5'b0,s5_adr}), .wb_dat_i({16'b0, s5_dat_mosi}),
         .wb_dat_o(err_data32), .wb_ack_o(s5_ack),
         // Write FIFO Interface
         .wr_data_i(_tx_err_data), .wr_ready_i(_tx_err_src_rdy), .wr_ready_o(_tx_err_dst_rdy),
@@ -444,7 +433,8 @@ module u1e_core
    ////////////////////////////////////////////////////////////////////////////
    // Interrupts
 
-   assign proc_int = (|err_status[1:0]);
+   always @(posedge wb_clk)
+     proc_int <= (|err_status[1:0]);
 
    // /////////////////////////////////////////////////////////////////////////
    // Settings Bus -- Slave #8 + 9