added async reset to oscillator

johnbentcope · Apr 17, 2024 · b77bc0f · b77bc0f
1 parent ab81376
commit b77bc0f
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Showing 2 changed files with 45 additions and 56 deletions.
diff --git a/src/constants.vh b/src/constants.vh
@@ -8,24 +8,19 @@ localparam [3:0] CTRL_INPUT_S       = 4'b0101;
 localparam [3:0] CTRL_INPUT_HOLD_S  = 4'b0110;
 localparam [3:0] CTRL_WIN_S         = 4'b0111;
 localparam [3:0] CTRL_LOSE_S        = 4'b1000;
-// localparam [20:0] MAX_TURN_TIME     = 21'hF_FFFF;
 localparam [20:0] MAX_TURN_TIME     = 21'h0_00FFF;
 
 // timer.v
 localparam [1:0] TIMR_IDLE_S      = 2'b00;
 localparam [1:0] TIMR_COUNT_S     = 2'b01;
-
 localparam [20:0] TIMR_MAX_C      = 21'h00_00F0;
-// localparam [20:0] TIMR_MAX_C      = 21'h0F_FFFF;
-
-// `define QUICK_PLAY
 
 `ifdef QUICK_PLAY
   localparam [24:0] FIVE_SECOND = 25'hFA;
   localparam [24:0] HALF_SECOND = 25'h19;
   localparam [24:0] QRTR_SECOND = 25'h0C;
 `else // human-time
-  localparam [24:0] FIVE_SECOND = 25'h000_C350;    //10KHz time
+  localparam [24:0] FIVE_SECOND = 25'h000_C350; //10KHz time
   localparam [24:0] HALF_SECOND = 25'h000_1388;
   localparam [24:0] QRTR_SECOND = 25'h000_09C4;
 `endif
diff --git a/src/oscillator.v b/src/oscillator.v
@@ -3,67 +3,61 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
+//============================================================================//
+// Oscillator
+//============================================================================//
+
 `define default_netname none
 
-module oscillator
-// #(
-//   parameter CLK_FREQ = 50_000_000_000
-// )
-(
+module oscillator (
   input  wire       CLK,      // Clock - 10KHz
   input  wire       RST_N,    // Reset_n - active low
   input  wire [1:0] NOTE_SEL, // Note selection
   output reg        AUDIO     // Oscillator output
 );
 
-//-------------------------------------------------------------------
-// note:        Hz : Cyc@10Mhz : Cyc@50Mhz
-// F#5 :  739.99Hz :   13_514  :    67_568
-// A 5 :  880.00Hz :   11_363  :    56_818
-// C#6 : 1108.70Hz :    9_020  :    45_098
-// E 6 : 1318.50Hz :    7_584  :    37_922
-//-------------------------------------------------------------------
-
-// Frequencies in millihertz
-// localparam Fs5_f =  739_990;
-// localparam A_5_f =  880_000;
-// localparam Cs6_f = 1108_700;
-// localparam E_6_f = 1318_500;
-
-reg [ 1: 0] current_note;             // 
-reg [13: 0] oscillator_counter;       // 
-reg [13: 0] counter_compares   [3:0]; // this seems expensive... optimize?
-
-initial begin
-  counter_compares[0] = 13_514;
-  counter_compares[1] = 11_363;
-  counter_compares[2] =  9_020;
-  counter_compares[3] =  7_584;
-end
-
-//-------------------------------------------------------------------
-// Okay so the state machine should never introduce a high frequency
-// runt pulse in the square wave generator.
-// Only at when toggling the output should a new counter value be loaded.
-//-------------------------------------------------------------------
-
-always @(posedge CLK) begin
-
-  // Handle reset.
-  if(!RST_N) begin
-    AUDIO               <=  0;
-    oscillator_counter  <= '0;
-    current_note        <= NOTE_SEL;
+  //-------------------------------------------------------------------
+  // note:        Hz : Cyc@10Mhz : Cyc@50Mhz
+  // F#5 :  739.99Hz :   13_514  :    67_568
+  // A 5 :  880.00Hz :   11_363  :    56_818
+  // C#6 : 1108.70Hz :    9_020  :    45_098
+  // E 6 : 1318.50Hz :    7_584  :    37_922
+  //-------------------------------------------------------------------
+
+  // Frequencies in millihertz
+  // localparam Fs5_f =  739_990;
+  // localparam A_5_f =  880_000;
+  // localparam Cs6_f = 1108_700;
+  // localparam E_6_f = 1318_500;
+
+  reg [ 1: 0] current_note;             // 
+  reg [13: 0] oscillator_counter;       // 
+  reg [13: 0] counter_compares   [3:0]; // this seems expensive... optimize?
+
+  initial begin
+    counter_compares[0] = 13_514;
+    counter_compares[1] = 11_363;
+    counter_compares[2] =  9_020;
+    counter_compares[3] =  7_584;
   end
 
-  else begin
-    oscillator_counter  <= oscillator_counter + 1;
-    if(oscillator_counter == counter_compares[current_note]) begin
-      current_note <= NOTE_SEL;
-      AUDIO <= !AUDIO;
+  //-------------------------------------------------------------------
+  // Okay so the state machine should never introduce a high frequency
+  // runt pulse in the square wave generator.
+  // Only at when toggling the output should a new counter value be loaded.
+  //-------------------------------------------------------------------
+  always @(posedge CLK or negedge RST_N) begin
+    if (!RST_N) begin
+      AUDIO               <= 0;
+      oscillator_counter  <= 0;
+      current_note        <= NOTE_SEL;
+    end else begin
+      oscillator_counter  <= oscillator_counter + 1;
+      if (oscillator_counter == counter_compares[current_note]) begin
+        current_note      <= NOTE_SEL;
+        AUDIO             <= !AUDIO;
+      end
     end
   end
 
-end
-
 endmodule : oscillator