1 files changed, 94 insertions, 0 deletions
diff --git a/fpga/usrp2/timing/time_receiver.v b/fpga/usrp2/timing/time_receiver.v
new file mode 100644
index 000000000..8e7d3f1ea
--- /dev/null
+++ b/fpga/usrp2/timing/time_receiver.v
@@ -0,0 +1,94 @@
+
+module time_receiver
+  (input clk, input rst,
+   output [31:0] master_time,
+   output sync_rcvd,
+   input exp_pps_in);
+
+   wire       code_err, disp_err, dispout, complete_word;
+   reg 	      disp_reg;
+   reg [9:0]  shiftreg;
+   reg [3:0]  bit_count;
+   wire [8:0] dataout;
+   reg [8:0]  dataout_reg;
+ 	      
+   always @(posedge clk)
+     shiftreg <= {exp_pps_in, shiftreg[9:1]};
+
+   localparam COMMA_0 = 10'h283;
+   localparam COMMA_1 = 10'h17c;
+   
+   wire       found_comma = (shiftreg == COMMA_0) | (shiftreg == COMMA_1);
+   wire       set_disp = (shiftreg == COMMA_1);
+
+   always @(posedge clk)
+     if(rst)
+       bit_count <= 0;
+     else if(found_comma | complete_word)
+       bit_count <= 0;
+     else 
+       bit_count <= bit_count + 1;
+   assign     complete_word = (bit_count == 9);
+
+   always @(posedge clk)
+     if(set_disp)
+       disp_reg <= 1;
+     else if(complete_word)
+       disp_reg <= dispout;
+
+   always @(posedge clk)
+     if(complete_word)
+       dataout_reg <= dataout;
+     
+   decode_8b10b decode_8b10b 
+     (.datain(shiftreg),.dispin(disp_reg),
+      .dataout(dataout),.dispout(dispout),
+      .code_err(code_err),.disp_err(disp_err) );
+
+   reg 	      error;
+   always @(posedge clk)
+     if(complete_word)
+       error <= code_err | disp_err;
+   
+   localparam STATE_IDLE = 0;
+   localparam STATE_T0 = 1;
+   localparam STATE_T1 = 2;
+   localparam STATE_T2 = 3;
+   localparam STATE_T3 = 4;
+   
+   localparam HEAD = 9'h13c;   
+
+   reg [7:0]  clock_a, clock_b, clock_c;
+   reg [2:0]  state;
+   
+   always @(posedge clk)
+     if(rst)
+       state <= STATE_IDLE;
+     else if(complete_word)
+       case(state)
+	 STATE_IDLE :
+	   if(dataout_reg == HEAD)
+	     state <= STATE_T0;
+	 STATE_T0 :
+	   begin
+	      clock_a <= dataout_reg[7:0];
+	      state <= STATE_T1;
+	   end
+	 STATE_T1 :
+	   begin
+	      clock_b <= dataout_reg[7:0];
+	      state <= STATE_T2;
+	   end
+	 STATE_T2 :
+	   begin
+	      clock_c <= dataout_reg[7:0];
+	      state <= STATE_T3;
+	   end
+	 STATE_T3 :
+	   state <= STATE_IDLE;
+       endcase // case(state)
+
+   assign master_time =  {clock_a, clock_b, clock_c, dataout_reg[7:0]};
+   assign sync_rcvd = (complete_word & (state == STATE_T3));
+
+endmodule // time_sender