aboutsummaryrefslogtreecommitdiffstats
path: root/usrp2/timing/time_receiver.v
blob: fd8651d29ed404c07d00a5bc8d34a9f530c3d1cf (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
module time_receiver
  (input clk, input rst,
   output reg [63:0] vita_time,
   output reg sync_rcvd,
   input exp_time_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_time_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 STATE_T4 = 5;
   localparam STATE_T5 = 6;
   localparam STATE_T6 = 7;
   localparam STATE_T7 = 8;
   localparam STATE_TAIL = 9;
   
   localparam HEAD = 9'h13c;   
   localparam TAIL = 9'h1F7;
   
   reg [3:0]  state;
   
   always @(posedge clk)
     if(rst)
       state <= STATE_IDLE;
     else if(complete_word)
       if(code_err | disp_err)
	 state <= STATE_IDLE;
       else
	 case(state)
	   STATE_IDLE :
	     if(dataout_reg == HEAD)
	       state <= STATE_T0;
	   STATE_T0 :
	     begin
		vita_time[63:56] <= dataout_reg[7:0];
		state <= STATE_T1;
	     end
	   STATE_T1 :
	     begin
		vita_time[55:48] <= dataout_reg[7:0];
		state <= STATE_T2;
	     end
	   STATE_T2 :
	     begin
		vita_time[47:40] <= dataout_reg[7:0];
		state <= STATE_T3;
	     end
	   STATE_T3 :
	     begin
		vita_time[39:32] <= dataout_reg[7:0];
		state <= STATE_T4;
	     end
	   STATE_T4 :
	     begin
		vita_time[31:24] <= dataout_reg[7:0];
		state <= STATE_T5;
	     end
	   STATE_T5 :
	     begin
		vita_time[23:16] <= dataout_reg[7:0];
		state <= STATE_T6;
	     end
	   STATE_T6 :
	     begin
		vita_time[15:8] <= dataout_reg[7:0];
		state <= STATE_T7;
	     end
	   STATE_T7 :
	     begin
		vita_time[7:0] <= dataout_reg[7:0];
		state <= STATE_TAIL;
	     end
	   STATE_TAIL :
	     state <= STATE_IDLE;
	 endcase // case(state)
   
   always @(posedge clk)
     if(rst)
       sync_rcvd <= 0;
     else
       sync_rcvd <= (complete_word & (state == STATE_TAIL) & (dataout_reg[8:0] == TAIL));
   
endmodule // time_sender