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Diffstat (limited to 'src/verilog/fmc_indicator.v')
| -rw-r--r-- | src/verilog/fmc_indicator.v | 69 |
1 files changed, 69 insertions, 0 deletions
diff --git a/src/verilog/fmc_indicator.v b/src/verilog/fmc_indicator.v new file mode 100644 index 0000000..a802a59 --- /dev/null +++ b/src/verilog/fmc_indicator.v @@ -0,0 +1,69 @@ +//====================================================================== +// +// fmc_indicator.v +// --------------- +// A simple LED indicator to show that the FMC is alive. +// +// +// Author: Pavel Shatov +// Copyright (c) 2015, 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 fmc_indicator + ( + input wire sys_clk, + input wire sys_rst, + input wire fmc_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 (fmc_active) cnt <= {CNT_BITS{1'b1}}; + + assign led_out = ~cnt[CNT_BITS-1]; + +endmodule + +//====================================================================== +// EOF fmc_indicator.v +//====================================================================== |