From 9a687bdb82eeb5f5133146bb3af6800d8435c75d Mon Sep 17 00:00:00 2001
From: Matt Ettus <matt@ettus.com>
Date: Thu, 21 Oct 2010 15:14:37 -0700
Subject: address gray coding
---
usrp2/extramfifo/nobl_if.v | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/usrp2/extramfifo/nobl_if.v b/usrp2/extramfifo/nobl_if.v
index 391a841e8..a8303deca 100644
--- a/usrp2/extramfifo/nobl_if.v
+++ b/usrp2/extramfifo/nobl_if.v
@@ -39,6 +39,12 @@ module nobl_if
assign RAM_LDn = 0;
// ZBT/NoBL RAM actually manages its own output enables very well.
assign RAM_OEn = 0;
+
+ // gray code the address to reduce EMI
+ wire [WIDTH-1:0] address_gray;
+
+ bin2gray #(.WIDTH(WIDTH)) bin2gray (.bin(address),.gray(address_gray));
+
//
// Pipeline stage 1
@@ -59,7 +65,7 @@ module nobl_if
if (enable)
begin
- address_pipe1 <= address;
+ address_pipe1 <= address_gray;
write_pipe1 <= write;
RAM_WEn <= ~write; // Creates IOB flob
--
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