design/audio/audio_buffer.sv

@@ -6,9 +6,6 @@
  * @date: 6/12/2025
  *
  * */
-
-//define used here because verilator needs it but vivado is smart enough
-//not to. 
 `ifdef VERILATOR
     `include "sdvd_defs.sv"
 `endif
@@ -75,6 +72,8 @@ always_ff @(posedge clk) begin
             // This will overflow to the correct value always
             address <= address + speed;
             enb <= 1;
+            // NOTE: I really don't know a good way to generate the load
+            // signal. It maybe could be an inverted 48khz clock?
             if (delay == 0) begin
                 sample <= doutb;
             end
@@ -87,7 +86,9 @@ always_ff @(posedge clk) begin
     end
 end
 
-//vivado block ram xpm macro
+//xpm_memory_sdpram #(
+//    .WRITE_DATA_WIDTH_A(16)
+//) buffer ();
 xpm_memory_sdpram #(
   .ADDR_WIDTH_A(11),               // DECIMAL
   .ADDR_WIDTH_B(10),               // DECIMAL
@@ -136,6 +137,7 @@ buffer (
 
   .enb(enb),              // 1-bit input: Memory enable signal for port B. Must be high on clock
                           // cycles when read operations are initiated. Pipelined internally.
+//active high reset
   .rstb(reset),            // 1-bit input: Reset signal for the final port B output register stage.
                           // Synchronously resets output port doutb to the value specified by
                           // parameter READ_RESET_VALUE_B.
@@ -145,10 +147,11 @@ buffer (
                           // writing one byte of dina to address addra. For example, to
                           // synchronously write only bits [15-8] of dina when WRITE_DATA_WIDTH_A
                           // is 32, wea would be 4'b0010.
-  
+  // Extra inputs that I guess I need
-  .sleep(0),              // The XPM macros say these can be removed, but when I did this the
+  .sleep(0),
-  .injectsbiterra(0),     // entire block memory got optimized out. These were readded in later
+  .injectsbiterra(0),
   .injectdbiterra(0),
+  // With a latency of 1 this surely does not matter
   .regceb(enb)
 );
 

design/low_freq_clock_gen.sv

@@ -6,7 +6,7 @@
  * @author: Waylon Cude, Dilanthi Prentice
  * @date: 6/12/2025
  * */
-//Define used because verilator needs it but vivado is samrt enough not to
+
 `ifdef VERILATOR
     `include "sdvd_defs.sv"
 `endif
@@ -19,7 +19,7 @@ module low_freq_clock_gen(
     output logic clk1k, clk10h, seconds_pulse
 );
 
-// Hardcoded to be 1,000,000/4,000 (25,000)
+// Hardcoded to be 1,000,000/4,000
 // Relying on constant maths makes it the wrong size
 localparam num_cycles = 25_000;
 

design/modular_clock_gen.sv

@@ -1,21 +1,18 @@
-/****
- * modular_clock_gen.sv - parameterizable clock divider.
- *
- * @author: Waylon Cude, Dilanthi Prentice
- * @date: 6/12/2025
- *
- * */
 module modular_clock_gen(
     input clk, reset,
     output logic oclk
 );
-//parameter has no default because the user should always set it
 parameter DIVISOR;
 
 logic [$clog2(DIVISOR)-1:0] counter;
 
 logic set;
 
+// clock will be high for about half of the cycle, depending on integer
+// rounding
+// OOPS this makes it combinational
+//assign oclk = counter < (DIVISOR/2);
+
 always_ff @(posedge clk) begin
     // modular clock has to keep ticking through reset
     // so everything with a synchronous reset actually works

design/nexys_a7_top.sv

@@ -118,13 +118,11 @@ audio_buffer audioBuffer(
     assign SD_DAT[3:1] = 'z;
     logic clk_100khz;
     logic clk_25mhz;
-    // We can clock this at around 200khz before things start breaking
+    // Actually 200khz now
-    // Even at 200khz sometimes things break
+    // 200khz is slightly unstable??????
     modular_clock_gen #(1000) slowSdClock(CLK100MHZ, reset, clk_100khz);
     // Try clocking this slower than max speed
-    // To see if that makes it actually work 
+    // To see if that makes it actually work ...
-    //
-    // NOTE: It did not make it work
     modular_clock_gen #(1000) fastSdClock(CLK100MHZ, reset, clk_25mhz);
     sd_controller realSdPlayer(
         clk_100khz,

design/sd/crc_gen.sv

@@ -1,11 +1,5 @@
-/***
+// parameterizable sequential crc generator
- * crc_gen.sv - paramerizable sequential crc generator. This could probably be
+// This probably could be combinational logic too, though it would be way slow
- *              combinational logic too (but it would be way slower)
- *
- * @author: Waylon Cude, Dilanthi Prentice
- * @date: 6/12/2025
- *
- * */
 module crc_gen #(
     parameter CRCBITS=7,
     parameter COMMANDLEN=40,

design/sd/read_command.sv

@@ -1,11 +1,3 @@
-/****
- * read_command.sv - reads the sd command line and listens for sd command
- *                   responses.
- * 
- * @author: Waylon Cude, Dilanthi Prentice
- * @date: 6/12/2025
- *
- * **/
 module read_command(
     input logic clk,
     input logic reset,
@@ -27,8 +19,8 @@ logic received_reg;
 
 logic [2:0] response_type_reg;
 
-// recevied was set a cycle before the data was actually ready
+// oops this was set a cycle before the data was actually ready
-// and if it's just a register it holds for too long
+// and if it's just a reg it holds for too long
 // use both for maximum reactivity
 assign received = received_reg && !listen;
 

design/sd/read_data.sv

@@ -1,12 +1,6 @@
-/***
+// Whenever we receive a data block, start spitting bytes out into the audio
- * read_data.sv - whenever we receive a data block, start spitting bytes out
+// buffer bram. This could always be clocked at the 25MHz default speed clock,
- *                into the audio buffer block ram. This could be clocked at
+// or it could switch over like the writer has to
- *                25MHz default speed clock, or it could swtich over like the
- *                writer has to.
- * @author: Waylon Cude, Dilanthi Prentice
- * @date: 6/12/2025
- *
- ***/
 module read_data(
     input clk,
     input reset,

design/sd/send_command.sv

@@ -1,11 +1,3 @@
-/***
- * send_command.sv - sends sd card commands. It takes in a command and an
- *                   argument and will figure out the necessary crc. 
- *
- * @author: Waylon Cude, Dilanthi Prentice
- * @date: 6/12/2025
- *
- * */
 module send_command(
     input clk, 
     // The crc should be clocked way faster than the sender

design/segment_display/seconds_display.sv

@@ -1,7 +1,5 @@
 /***
-* sixty_display.sv - converts a binary digit from zero to fifty-nine to its
+* seconds_display.sv - converts a five bit seconds counter to its seven segement display equivalent.
-*                    ones and tens digits and then gets the seven segment
-*                    display equivalents of them.
 *
 * @author: Dilanthi Prentice, Waylon Cude
 * @date: 6/12/25
@@ -18,14 +16,14 @@ module seconds_display
 logic [4:0] ones_digit; 
 logic [4:0] tens_digit;
 
-//convert digit to ones and tens places
 always_comb
 begin
     ones_digit = seconds % 10;
     tens_digit = seconds / 10;
 end
 
-//convert both ones and tens place digits to their seven segement equivalent
+//instantiate the display_converter to convert the counter
+//to a seven segment display number
 display_converter ones (ones_digit, display_ones);
 display_converter tens (tens_digit, display_tens);
 

doc/bugs.md

@@ -38,7 +38,7 @@
   entirely. Detected in testbench
 - off-by-one error detected in the counter
 
-### read_data
+## read_data
 - audio buffer address to write to was never changing, caught in simulation
 - some off-by-one errors in the byte shifting were found and corrected