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-rw-r--r--src/rtl/toggle.v92
1 files changed, 92 insertions, 0 deletions
diff --git a/src/rtl/toggle.v b/src/rtl/toggle.v
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+//======================================================================
+//
+// toggle
+// ------
+// gpio pin toggler.
+//
+//
+// Author: Joachim Strombergson
+// Copyright (c) 2018, 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 toggle
+
+ (
+ input wire sys_clk,
+ input wire reset_n,
+ output wire [7 : 0] gpio_b
+ );
+
+ localparam TOGGLE_DELAY_CYCLES = 100;
+
+ reg [7 : 0] toggle_ctr_reg;
+ reg [7 : 0] toggle_ctr_new;
+
+ reg toggle_reg;
+ reg toggle_we;
+
+ assign gpio_b = {7'b1010101, toggle_reg};
+
+ always @(posedge sys_clk)
+ begin: sys_clk_toggle_reg_update
+ if (!reset_n)
+ begin
+ toggle_ctr_reg <= 32'h0;
+ toggle_reg <= 1'b0;
+ end
+ else
+ begin
+ toggle_ctr_reg <= toggle_ctr_new;
+
+ if (toggle_we)
+ toggle_reg <= ~toggle_reg;
+ end
+ end
+
+ always @*
+ begin : sys_clk_toggle
+ if (toggle_ctr_reg == TOGGLE_DELAY_CYCLES)
+ begin
+ toggle_ctr_new = 32'h0;
+ toggle_we = 1'b1;
+ end
+ else
+ begin
+ toggle_ctr_new = toggle_ctr_reg + 1'b1;
+ toggle_we = 1'b0;
+ end
+ end
+
+endmodule // toggle
+
+//======================================================================
+// EOF toggle.v
+//======================================================================