From 0ce0835a4568822ab7f29d6dae1d028a7c8523f3 Mon Sep 17 00:00:00 2001
From: Aadi Desai <21363892+supleed2@users.noreply.github.com>
Date: Tue, 16 May 2023 22:11:17 +0100
Subject: [PATCH] Working version of sample generator

---
 rtl/genSaw.sv | 40 ++++++++++++++++++++--------------------
 1 file changed, 20 insertions(+), 20 deletions(-)

diff --git a/rtl/genSaw.sv b/rtl/genSaw.sv
index 5e267e4..493f22b 100644
--- a/rtl/genSaw.sv
+++ b/rtl/genSaw.sv
@@ -4,36 +4,36 @@ module genSaw
 ( input  var        i_clk48
 , input  var        i_rst48_n
 , input  var        i_pause
-, input  var [23:0] i_tf
-, output var [47:0] o_lr
-, output var        o_new_pulse
+, input  var [23:0] i_targetf
+, output var [15:0] o_sample
+, output var        o_pulse
 );
 
 logic [8:0] clk_div;
-always_ff @(posedge i_clk48)
-  if (!i_rst48_n)             clk_div <= 0; // Reset if reset is low
-  else if (clk_div == 9'd500) clk_div <= 0; // Reset count every 500 cycles
-  else                        clk_div <= clk_div + 1; // Increment otherwise
+always_ff @(posedge i_clk48) // Count half 48kHz cycle
+  if (!i_rst48_n)             clk_div <= 0;
+  else if (clk_div == 9'd499) clk_div <= 0;
+  else                        clk_div <= clk_div + 1;
 
 logic clk_48k;
-always_ff @(posedge i_clk48)
-  if (!i_rst48_n)             clk_48k <= 0; // Reset if reset is low
-  else if (clk_div == 9'd500) clk_48k <= ~clk_48k; // Invert every 500 cycles
+always_ff @(posedge i_clk48) // Generate 48kHz clock
+  if (!i_rst48_n)           clk_48k <= 0;
+  else if (clk_div == 9'd0) clk_48k <= ~clk_48k;
 
 logic clk_48k_past;
-always_ff @(posedge i_clk48)
-  clk_48k_past <= clk_48k; // 1 cycle delayed version of 48kHz clock
+always_ff @(posedge i_clk48) // Track rising / falling edge of 48kHz clock
+  clk_48k_past <= clk_48k;
 
-assign o_new_pulse = clk_48k && !clk_48k_past; // Detect rising edge of 48kHz clock
+assign o_pulse = clk_48k && !clk_48k_past; // Detect rising edge of 48kHz clock
 
-logic [23:0] saw_step;
-assign saw_step = (24'd699 * i_tf) >> 1; // Sawtooth step calc from input target freq
+logic [23:0] int_saw_step;
+assign int_saw_step = (24'd699 * i_targetf); // Sawtooth step calc from input target freq
 
-logic [23:0] waveform;
-always_ff @(posedge clk_48k)
-  if (!i_rst48_n)    waveform <= '0; // Reset if reset is low
-  else if (!i_pause) waveform <= waveform + saw_step; // Add saw step if not paused (48kHz)
+logic [15:0] saw_step;
+assign saw_step = {1'b0, int_saw_step[23:9]}; // Shift step right correctly (2^9)
 
-assign o_lr = {waveform, waveform}; // Output same sample to left & right
+always_ff @(posedge clk_48k) // Generate new sample on rising edge of 48kHz clock
+  if (!i_rst48_n)    o_sample <= '0;
+  else if (!i_pause) o_sample <= o_sample + saw_step; // Add saw_step if not paused (48kHz)
 
 endmodule