update JT12

rtl/sound/jt49/jt49_cen.v

@@ -0,0 +1,55 @@
+/*  This file is part of JT49.
+
+    JT49 is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    JT49 is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with JT49.  If not, see <http://www.gnu.org/licenses/>.
+    
+    Author: Jose Tejada Gomez. Twitter: @topapate
+    Version: 1.0
+    Date: 10-Nov-2018
+    
+    Based on sqmusic, by the same author
+    
+    */
+
+module jt49_cen(
+    input       clk,
+    input       rst_n,
+    input       cen,    // base clock enable signal
+    input       sel,    // when low, divide by 2 once more
+    output  reg cen16,
+    output  reg cen256
+);
+
+reg [9:0] cencnt;
+parameter CLKDIV = 3; // use 3 for standalone JT49 or 2
+localparam eg = CLKDIV; //8;
+
+wire toggle16 = sel ? ~|cencnt[CLKDIV-1:0] : ~|cencnt[CLKDIV:0];
+wire toggle256= sel ? ~|cencnt[eg-2:0]     : ~|cencnt[eg-1:0];
+
+
+always @(posedge clk, negedge rst_n) begin
+    if(!rst_n)
+        cencnt <= 10'd0;
+    else begin 
+        if(cen) cencnt <= cencnt+10'd1;
+    end
+end
+
+always @(posedge clk) begin
+    cen16  <= cen & toggle16;
+    cen256 <= cen & toggle256;
+end
+
+
+endmodule // jt49_cen