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diff --git a/fpga/usrp2/control_lib/atr_controller.v b/fpga/usrp2/control_lib/atr_controller.v
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+//
+// 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/>.
+//
+
+
+// Automatic transmit/receive switching of control pins to daughterboards
+// Store everything in registers for now, but could use a RAM for more
+// complex state machines in the future
+
+module atr_controller
+  (input clk_i, input rst_i,
+   input [5:0] adr_i, input [3:0] sel_i, input [31:0] dat_i, output reg [31:0] dat_o,
+   input we_i, input stb_i, input cyc_i, output reg ack_o,
+   input run_rx, input run_tx,
+   output [31:0] ctrl_lines);
+   
+   reg [3:0] state;
+   reg [31:0] atr_ram [0:15];  // DP distributed RAM
+
+   // WB Interface
+   always @(posedge clk_i)
+     if(we_i & stb_i & cyc_i)
+       begin
+	  if(sel_i[3])
+	    atr_ram[adr_i[5:2]][31:24] <= dat_i[31:24];
+	  if(sel_i[2])
+	    atr_ram[adr_i[5:2]][23:16] <= dat_i[23:16];
+	  if(sel_i[1])
+	    atr_ram[adr_i[5:2]][15:8] <= dat_i[15:8];
+	  if(sel_i[0])
+	    atr_ram[adr_i[5:2]][7:0] <= dat_i[7:0];
+       end // if (we_i & stb_i & cyc_i)
+
+   always @(posedge clk_i)
+     dat_o <= atr_ram[adr_i[5:2]];
+   
+   always @(posedge clk_i)
+     ack_o <= stb_i & cyc_i & ~ack_o;
+
+   // Control side of DP RAM
+   assign     ctrl_lines = atr_ram[state];
+
+   // Put a more complex state machine with time delays and multiple states here
+   //  if daughterboard requires more complex sequencing
+   localparam ATR_IDLE = 4'd0;
+   localparam ATR_TX = 4'd1;
+   localparam ATR_RX = 4'd2;
+   localparam ATR_FULL_DUPLEX = 4'd3;
+   
+   always @(posedge clk_i)
+     if(rst_i)
+       state <= ATR_IDLE;
+     else
+       case ({run_rx,run_tx})
+	 2'b00 : state <= ATR_IDLE;
+	 2'b01 : state <= ATR_TX;
+	 2'b10 : state <= ATR_RX;
+	 2'b11 : state <= ATR_FULL_DUPLEX;
+       endcase // case({run_rx,run_tx})
+   
+endmodule // atr_controller