timestamp_snapshot.v 3.89 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11
/*!
 * <b>Module:</b>timestamp_snapshot
 * @file timestamp_snapshot.v
 * @date 2015-07-03  
 * @author Andrey Filippov     
 *
 * @brief Take timestamp snapshot and send the ts message over the 8-bit bus
 *
 * @copyright Copyright (c) 2015 Elphel, Inc.
 *
 * <b>License:</b>
12 13 14 15 16 17 18 19 20 21 22 23 24
 *
 * timestamp_snapshot.v 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.
 *
 *  timestamp_snapshot.v 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/> .
25 26 27 28 29 30
 *
 * Additional permission under GNU GPL version 3 section 7:
 * If you modify this Program, or any covered work, by linking or combining it
 * with independent modules provided by the FPGA vendor only (this permission
 * does not extend to any 3-rd party modules, "soft cores" or macros) under
 * different license terms solely for the purpose of generating binary "bitstream"
31
 * files and/or simulating the code, the copyright holders of this Program give
32 33
 * you the right to distribute the covered work without those independent modules
 * as long as the source code for them is available from the FPGA vendor free of
Andrey Filippov's avatar
Andrey Filippov committed
34
 * charge, and there is no dependence on any encrypted modules for simulating of
35 36 37
 * the combined code. This permission applies to you if the distributed code
 * contains all the components and scripts required to completely simulate it
 * with at least one of the Free Software programs.
38
 */
39 40 41
`timescale 1ns/1ps

module  timestamp_snapshot(
Andrey Filippov's avatar
Andrey Filippov committed
42
//    input                rst,
43 44 45 46 47
    input                tclk, // clock that drives time counters
    input         [31:0] sec,  // @tclk: current time seconds
    input         [19:0] usec, // @tclk: current time microseconds
    // snapshot destination clock domain
    input                sclk,
Andrey Filippov's avatar
Andrey Filippov committed
48
    input                srst, // @ posedge sclk - sync reset
49
    input                snap,
Andrey Filippov's avatar
Andrey Filippov committed
50
    output reg           pre_stb, // one clock pulse before sending TS data
51 52 53 54 55 56 57 58
    output reg     [7:0] ts_data  // timestamp data (s0,s1,s2,s3,u0,u1,u2,u3==0)
);
    wire         snap_tclk;
    reg   [51:0] sec_usec_snap;
    wire         pulse_busy;
    reg          pulse_busy_r;
    reg    [2:0] cntr;
    reg          snd;
Andrey Filippov's avatar
Andrey Filippov committed
59
    wire         pre_stb_w;
60

Andrey Filippov's avatar
Andrey Filippov committed
61
    assign pre_stb_w = !pulse_busy && pulse_busy_r;
62 63 64 65 66
    
    always @ (posedge tclk) begin
        if (snap_tclk) sec_usec_snap <= {usec,sec};
    end
    
Andrey Filippov's avatar
Andrey Filippov committed
67 68
    always @(posedge sclk) begin
        if      (srst)                         snd <= 0;
69 70
        else if (!pulse_busy && pulse_busy_r)  snd <= 1;
        else if ((&cntr) || snap)              snd <= 0;
Andrey Filippov's avatar
Andrey Filippov committed
71
        pre_stb <= pre_stb_w;
72 73 74 75 76
    end

    always @(posedge sclk) begin

        pulse_busy_r <= pulse_busy;
77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95
        
        if (!snd) cntr <= 0;
        else      cntr <=  cntr + 1;
        
        if (snd) case (cntr)
            3'h0: ts_data <= sec_usec_snap[ 7: 0];
            3'h1: ts_data <= sec_usec_snap[15: 8];
            3'h2: ts_data <= sec_usec_snap[23:16];
            3'h3: ts_data <= sec_usec_snap[31:24];
            3'h4: ts_data <= sec_usec_snap[39:32];
            3'h5: ts_data <= sec_usec_snap[47:40];
            3'h6: ts_data <= {4'b0,sec_usec_snap[51:48]};
            3'h7: ts_data <= 8'b0;
        endcase
    end
    
    pulse_cross_clock #(
        .EXTRA_DLY (1)
    ) snap_tclk_i (
Andrey Filippov's avatar
Andrey Filippov committed
96
        .rst       (srst), // input
97 98 99 100 101 102 103 104 105 106
        .src_clk   (sclk), // input
        .dst_clk   (tclk), // input
        .in_pulse  (snap), // input
        .out_pulse (snap_tclk), // output
        .busy      (pulse_busy) // output
    );
    

endmodule