link_timer: Generate link timer pulse (1.6 and 10 ms) per SGMII and IEEE 802.3

1 files changed, 68 insertions, 0 deletions

diff --git a/source/link_timer.v b/source/link_timer.v
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+++ b/source/link_timer.v
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+/*
+ *       link_timer.v
+ *
+ *   Copyright 2020 Mind Chasers Inc.
+ *
+ *   Licensed under the Apache License, Version 2.0 (the "License");
+ *   you may not use this file except in compliance with the License.
+ *   You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *   Unless required by applicable law or agreed to in writing, software
+ *   distributed under the License is distributed on an "AS IS" BASIS,
+ *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *   See the License for the specific language governing permissions and
+ *   limitations under the License.
+ *
+ *	function: Generate link timer pulse (1.6 and 10 ms) per SGMII and IEEE 802.3
+ *	
+ */
+
+module link_timer(
+	input rstn,
+	input	clk,			// 125 MHz data clock
+	output 	pulse_1_6ms,
+	output	pulse_10ms
+);
+
+	wire clk;
+	reg [13:0] cnt;		// 0.1 ms counter
+	reg [3:0]  cnt_1_6ms;
+	reg [6:0]  cnt_10ms;
+	
+	// 0.1 ms counter
+	always @ (posedge clk or negedge rstn) 
+	   if  ( !rstn )
+		   cnt <= 'd0;
+	   else if (cnt == 'd12500)
+	   		cnt <= 'd0;
+	   else
+		   cnt <= cnt + 1;
+	   
+   // 1.6 ms counter
+   always @ (posedge clk or negedge rstn) 
+   	if  ( !rstn )
+   		cnt_1_6ms <= 'd0;
+	else if (cnt == 'd12500)
+		if (cnt_1_6ms == 'd16)
+			cnt_1_6ms <= 'd0;
+		else
+			cnt_1_6ms <= cnt_1_6ms + 1;
+   	
+   	assign pulse_1_6ms = (cnt == 'd12500 && cnt_1_6ms == 'd15);
+   	
+   	// 10 ms counter
+   	always @ (posedge clk or negedge rstn) 
+   		if  ( !rstn )
+   			cnt_10ms <= 'd0;
+	else if (cnt == 'd12500)
+   		if (cnt_10ms == 'd99)
+   			cnt_10ms <= 'd0;
+   		else
+   			cnt_10ms <= cnt_10ms + 1;
+   		
+   	assign pulse_10ms = (cnt == 'd12500 && cnt_10ms == 'd99);
+	   
+	   
+endmodule
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