Squashed B200 FPGA Source. Code from Josh Blum, Ian Buckley, and Matt Ettus.

Original-commit: 0df4b801a34697f2058b4a7b95e08d2a0576c9db

lib/timing/timekeeper.v

@@ -0,0 +1,68 @@
+//
+// Copyright 2013 Ettus Research LLC
+//
+
+
+module timekeeper
+  #(parameter BASE = 0)
+   (input clk, input reset, input pps,
+    input set_stb, input [7:0] set_addr, input [31:0] set_data,
+    output reg [63:0] vita_time, output reg [63:0] vita_time_lastpps);
+
+   //////////////////////////////////////////////////////////////////////////
+   // timer settings for this module
+   //////////////////////////////////////////////////////////////////////////
+   wire [63:0] time_at_next_event;
+   wire set_time_pps, set_time_now;
+   wire cmd_trigger;
+
+   setting_reg #(.my_addr(BASE), .width()) sr_time_hi
+     (.clk(clk), .rst(reset), .strobe(set_stb), .addr(set_addr), .in(set_data),
+      .out(time_at_next_event[63:32]), .changed());
+   
+   setting_reg #(.my_addr(BASE+1), .width()) sr_time_lo
+     (.clk(clk), .rst(reset), .strobe(set_stb), .addr(set_addr), .in(set_data),
+      .out(time_at_next_event[31:0]), .changed());
+   
+   setting_reg #(.my_addr(BASE+2), .width(2)) sr_ctrl
+     (.clk(clk), .rst(reset), .strobe(set_stb), .addr(set_addr), .in(set_data),
+      .out({set_time_pps, set_time_now}), .changed(cmd_trigger));
+
+   //////////////////////////////////////////////////////////////////////////
+   // PPS edge detection logic
+   //////////////////////////////////////////////////////////////////////////
+   reg pps_del, pps_del2;
+   always @(posedge clk)
+     {pps_del2,pps_del} <= {pps_del, pps};
+
+   wire pps_edge = !pps_del2 & pps_del;
+
+   //////////////////////////////////////////////////////////////////////////
+   // track the time at last pps so host can detect the pps
+   //////////////////////////////////////////////////////////////////////////
+   always @(posedge clk)
+     if(pps_edge) vita_time_lastpps <= vita_time;
+
+   //////////////////////////////////////////////////////////////////////////
+   // arm the trigger to latch a new time when the ctrl register is written
+   //////////////////////////////////////////////////////////////////////////
+   reg armed;
+   wire time_event = armed && ((set_time_now) || (set_time_pps && pps_edge));
+   always @(posedge clk) begin
+     if (reset) armed <= 1'b0;
+     else if (cmd_trigger) armed <= 1'b1;
+     else if (time_event) armed <= 1'b0;
+   end
+
+   //////////////////////////////////////////////////////////////////////////
+   // vita time tracker - update every tick or when we get an "event"
+   //////////////////////////////////////////////////////////////////////////
+   always @(posedge clk)
+     if(reset)
+       vita_time <= 64'h0;
+     else if (time_event)
+       vita_time <= time_at_next_event;
+     else
+       vita_time <= vita_time + 64'h1;
+
+endmodule // timekeeper