From af018ded46343f7dba752b54a8600b5afcb656cb Mon Sep 17 00:00:00 2001
From: Josh Blum <josh@joshknows.com>
Date: Tue, 8 May 2012 13:45:26 -0700
Subject: fpga: xclock fix for edge case condition
---
usrp2/gpmc/cross_clock_reader.v | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/usrp2/gpmc/cross_clock_reader.v b/usrp2/gpmc/cross_clock_reader.v
index a30e0385f..a8366badc 100644
--- a/usrp2/gpmc/cross_clock_reader.v
+++ b/usrp2/gpmc/cross_clock_reader.v
@@ -1,5 +1,5 @@
//
-// Copyright 2011 Ettus Research LLC
+// Copyright 2011-2012 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
@@ -26,17 +26,19 @@ module cross_clock_reader
output reg [WIDTH-1:0] out
);
- reg [WIDTH-1:0] shadow;
+ reg [WIDTH-1:0] shadow0, shadow1;
always @(posedge clk) begin
if (rst) begin
out <= DEFAULT;
- shadow <= DEFAULT;
+ shadow0 <= DEFAULT;
+ shadow1 <= DEFAULT;
end
- else if (shadow == in) begin
- out <= shadow;
+ else if (shadow0 == shadow1) begin
+ out <= shadow1;
end
- shadow <= in;
+ shadow0 <= in;
+ shadow1 <= shadow0;
end
endmodule //cross_clock_reader
--
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