diff options
Diffstat (limited to 'rtl/src/verilog/eim_indicator.v')
| -rw-r--r-- | rtl/src/verilog/eim_indicator.v | 112 |
1 files changed, 76 insertions, 36 deletions
diff --git a/rtl/src/verilog/eim_indicator.v b/rtl/src/verilog/eim_indicator.v index 1324afb..56c7190 100644 --- a/rtl/src/verilog/eim_indicator.v +++ b/rtl/src/verilog/eim_indicator.v @@ -1,36 +1,76 @@ -`timescale 1ns / 1ps
-
-module eim_indicator
- (
- sys_clk, sys_rst,
- eim_active,
- led_out
- );
-
- //
- // Ports
- //
- input wire sys_clk;
- input wire sys_rst;
- input wire eim_active;
- output wire led_out;
-
- //
- // Parameters
- //
- localparam CNT_BITS = 24; // led will be dim for 2**(24-1) = 8388608 ticks, which is ~100 ms @ 80 MHz.
-
- //
- // Counter
- //
- reg [CNT_BITS-1:0] cnt;
-
- always @(posedge sys_clk)
- //
- if (sys_rst) cnt <= {CNT_BITS{1'b0}};
- else if (cnt > {CNT_BITS{1'b0}}) cnt <= cnt - 1'b1;
- else if (eim_active) cnt <= {CNT_BITS{1'b1}};
-
- assign led_out = ~cnt[CNT_BITS-1];
-
-endmodule
+//====================================================================== +// +// eim_indicator.v +// --------------- +// A simple LED indicator to show that the EIM is alive. +// +// +// Author: Pavel Shatov +// Copyright (c) 2014, NORDUnet A/S All rights reserved. +// +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions +// are met: +// - Redistributions of source code must retain the above copyright +// notice, this list of conditions and the following disclaimer. +// +// - Redistributions in binary form must reproduce the above copyright +// notice, this list of conditions and the following disclaimer in the +// documentation and/or other materials provided with the distribution. +// +// - Neither the name of the NORDUnet nor the names of its contributors may +// be used to endorse or promote products derived from this software +// without specific prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS +// IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED +// TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A +// PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +// HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED +// TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR +// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF +// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING +// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS +// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. +// +//====================================================================== + +module eim_indicator + ( + sys_clk, sys_rst, + eim_active, + led_out + ); + + // + // Ports + // + input wire sys_clk; + input wire sys_rst; + input wire eim_active; + output wire led_out; + + // + // Parameters + // + localparam CNT_BITS = 24; // led will be dim for 2**(24-1) = 8388608 ticks, which is ~100 ms @ 80 MHz. + + // + // Counter + // + reg [CNT_BITS-1:0] cnt; + + always @(posedge sys_clk) + // + if (sys_rst) cnt <= {CNT_BITS{1'b0}}; + else if (cnt > {CNT_BITS{1'b0}}) cnt <= cnt - 1'b1; + else if (eim_active) cnt <= {CNT_BITS{1'b1}}; + + assign led_out = ~cnt[CNT_BITS-1]; + +endmodule + +//====================================================================== +// EOF eim_indicator.v +//====================================================================== |