Typo fixup

Reviewed-on: #2

design/audio/audio_buffer.sv

@@ -1,6 +1,15 @@
+/****
+ * audio_buffer.sv - holds a 2KiB audio buffer of 16-bit pcm audio
+ *                   samples (with pcm being the audio format we are using)
+ *
+ * @author: Waylon Cude, Dilanthi
+ * @date: 6/12/2025
+ *
+ * */
 `ifdef VERILATOR
     `include "sdvd_defs.sv"
 `endif
+
 import sdvd_defs::SPEED;
 
 //this interfaces with block ram
@@ -12,9 +21,6 @@ module audio_buffer(
     input logic play, stop,
     input SPEED speed,
 
-    // Whether the current address being read from is in the upper or lower
-    // half of the 2KiB buffer
-    output logic address_half,
 
     // Whether the audio buffer is currently playing
     output logic playing,
@@ -23,11 +29,13 @@ module audio_buffer(
     output logic [15:0] sample,
 
     // Inputs for the memory buffer
-    input logic [10:0] addra,
+    audio_buffer_interface.receiver driver
-    input logic [7:0] dina,
-    input logic clka, ena
 );
 
+// Whether the current address being read from is in the upper or lower
+// half of the 2KiB buffer
+let address_half = driver.address_half;
+
 logic [9:0] address;
 
 // State register
@@ -117,16 +125,16 @@ xpm_memory_sdpram #(
 )
 buffer (
   .doutb(doutb),          // READ_DATA_WIDTH_B-bit output: Data output for port B read operations.
-  .addra(addra),          // ADDR_WIDTH_A-bit input: Address for port A write operations.
+  .addra(driver.addra),          // ADDR_WIDTH_A-bit input: Address for port A write operations.
   .addrb(address),        // ADDR_WIDTH_B-bit input: Address for port B read operations.
-  .clka(clka),            // 1-bit input: Clock signal for port A. Also clocks port B when
+  .clka(driver.clka),            // 1-bit input: Clock signal for port A. Also clocks port B when
                           // parameter CLOCKING_MODE is "common_clock".
 
   .clkb(clk),             // 1-bit input: Clock signal for port B when parameter CLOCKING_MODE is
                           // "independent_clock". Unused when parameter CLOCKING_MODE is
                           // "common_clock".
-  .dina(dina),            // WRITE_DATA_WIDTH_A-bit input: Data input for port A write operations.
+  .dina(driver.dina),            // WRITE_DATA_WIDTH_A-bit input: Data input for port A write operations.
-  .ena(ena),              // 1-bit input: Memory enable signal for port A. Must be high on clock
+  .ena(driver.ena),              // 1-bit input: Memory enable signal for port A. Must be high on clock
                           // cycles when write operations are initiated. Pipelined internally.
 
   .enb(enb),              // 1-bit input: Memory enable signal for port B. Must be high on clock
@@ -135,7 +143,7 @@ buffer (
   .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.
-  .wea(ena)               // WRITE_DATA_WIDTH_A/BYTE_WRITE_WIDTH_A-bit input: Write enable vector
+  .wea(driver.ena)               // WRITE_DATA_WIDTH_A/BYTE_WRITE_WIDTH_A-bit input: Write enable vector
                           // for port A input data port dina. 1 bit wide when word-wide writes are
                           // used. In byte-wide write configurations, each bit controls the
                           // writing one byte of dina to address addra. For example, to

design/audio/pwm.sv

@@ -1,8 +1,9 @@
 /****
- * pwm.sv - [must edit in future]
+ * pwm.sv - drives the pwm audio output on the FPGA given a single 16-bit
+ *          sample. 
  *
  * @author: Dilanthi Prentice, Waylon Cude
- * @date: [not sure when due yet]
+ * @date: 6-12-2025
  *
  *
  * */

design/debouncer.sv

@@ -1,3 +1,11 @@
+/***
+ * debouncer.sv - generates a debounced button press and turns it into
+ *                a single pulse.
+ *
+ * @author: Waylon Cude, Dilanthi Prentice
+ * @date: 6-12-25
+ *
+ * */
 //NOTE: you should drive this with a slow clock to actually debounce input
 module debouncer(input logic clk, input reset, input source, output logic out);
 

design/low_freq_clock_gen.sv

@@ -1,3 +1,12 @@
+/****
+ * low_freq_clock_gen.sv - Generates different clock frequencies to drive
+ *                         different state machines and different parts of
+ *                         the design. 
+ *
+ * @author: Waylon Cude, Dilanthi Prentice
+ * @date: 6/12/2025
+ * */
+
 `ifdef VERILATOR
     `include "sdvd_defs.sv"
 `endif

design/nexys_a7_top.sv

@@ -1,3 +1,10 @@
+/***
+ * nexys_a7_top.sv - top level design module specific to Nexys A7100T.
+ *
+ * @author: Waylon Cude, Dilanthi Prentice
+ * @date: 6/12/2025
+ *
+ * **/
 `ifdef VERILATOR
     `include "sdvd_defs.sv"
 `endif

design/sd/rom_sd.sv

@@ -0,0 +1,103 @@
+// A dummy sdcard module for testing the audio port
+
+module sd(
+    input logic clk,
+    input logic reset,
+    output logic ready,
+
+    audio_buffer_interface.driver audio_buffer
+);
+
+// First we write 2048B into the memory buffer, then signal to play it and
+// wait for half signal to avoid overwriting memory
+logic initializing;
+logic [16:0] rom_address;
+logic [7:0] rom_data;
+logic rom_enable;
+// Keep track of pipeline delay so we don't write garbage into the buffer
+logic delay;
+
+// Keep track of if we are caught up to the buffer or not
+logic waiting;
+//TODO: This probably could be an assign, not sure
+
+assign ready = '1;
+
+always_ff @(posedge clk) begin
+    if (reset) begin
+        delay <= 1;
+        rom_address <= 0;
+        initializing <= 1;
+        audio_buffer.addra <= 0;
+        audio_buffer.ena <= 0;
+    end
+    else if (initializing) begin
+        rom_enable <= 1;
+        case (delay)
+            1:  delay <= 0;
+            0:  begin
+                rom_address <= 1;
+                delay <= 0;
+                initializing <= 0;
+                end
+        endcase
+    end
+    else begin
+        if (!waiting) begin
+            audio_buffer.ena <= 1;
+            audio_buffer.dina <= rom_data;
+            audio_buffer.addra <= audio_buffer.addra + 1;
+        end
+
+    end
+
+    
+
+end
+
+
+// xpm_memory_sprom: Single Port ROM
+// Xilinx Parameterized Macro, version 2024.2
+
+// The ROM has 17 address bits and 8 data bits to store 128KiB, more than
+// enough for one second of 48khz audio
+xpm_memory_sprom #(
+  .ADDR_WIDTH_A(17),              // DECIMAL
+  .AUTO_SLEEP_TIME(0),           // DECIMAL
+  .CASCADE_HEIGHT(0),            // DECIMAL
+  .ECC_BIT_RANGE("7:0"),         // String
+  .ECC_MODE("no_ecc"),           // String
+  .ECC_TYPE("none"),             // String
+  .IGNORE_INIT_SYNTH(0),         // DECIMAL
+  .MEMORY_INIT_FILE("roundabout.mem"),     // String
+  .MEMORY_INIT_PARAM("0"),       // String
+  .MEMORY_OPTIMIZATION("true"),  // String
+  .MEMORY_PRIMITIVE("auto"),     // String
+  .MEMORY_SIZE(131072*8),            // DECIMAL
+  .MESSAGE_CONTROL(0),           // DECIMAL
+  .RAM_DECOMP("auto"),           // String
+  .READ_DATA_WIDTH_A(8),        // DECIMAL
+  .READ_LATENCY_A(2),            // DECIMAL
+  .READ_RESET_VALUE_A("0"),      // String
+  .RST_MODE_A("SYNC"),           // String
+  .SIM_ASSERT_CHK(0),            // DECIMAL; 0=disable simulation messages, 1=enable simulation messages
+  .USE_MEM_INIT(1),              // DECIMAL
+  .USE_MEM_INIT_MMI(0),          // DECIMAL
+  .WAKEUP_TIME("disable_sleep")  // String
+)
+xpm_memory_sprom_inst (
+  .douta(rom_data),                   // READ_DATA_WIDTH_A-bit output: Data output for port A read operations.
+  .addra(rom_address),                   // ADDR_WIDTH_A-bit input: Address for port A read operations.
+  .clka(clk),                     // 1-bit input: Clock signal for port A.
+  .ena(rom_enable),                       // 1-bit input: Memory enable signal for port A. Must be high on clock
+                                   // cycles when read operations are initiated. Pipelined internally.
+
+  .rsta(reset)                     // 1-bit input: Reset signal for the final port A output register stage.
+                                   // Synchronously resets output port douta to the value specified by
+                                   // parameter READ_RESET_VALUE_A.
+);
+
+// End of xpm_memory_sprom_inst instantiation
+				
+
+endmodule

design/segment_display/display_anode_driver.sv

@@ -1,4 +1,16 @@
-// NOTE: This expects to be driven with a 100khz clock
+/***
+ * display_anode_driver.sv - Turns on a single anode of a single digit at a time,
+ *                           rapidly rotating through all of them, generating
+ *                           a solid-looking display even though only one digit
+ *                           is on at a time.
+ *
+ * @author: Waylon Cude, Dilanthi Prentice
+ * @date: 6-12-2025
+ *
+ * */
+
+// NOTE: This expects to be driven with a 100khz clock but can be altered in
+// the nexys_a7_top.sv file.
 module display_anode_driver(
     input logic clk, 
     input logic reset, 

design/segment_display/display_converter.sv

@@ -1,12 +1,12 @@
 /**
 * display_converter.sv - decodes a 5 bit digit input into its seven segment
 *                        display equivalent using a lookup table. Display can
-*                        do 0 - 9, A - F, individual segmentsm and special
+*                        do 0 - 9, A - F, individual segments and special
 *                        characters.  
+*
 * @author: Dilanthi Prentice, Waylon Cude
 * @date: 6/12/25
 *
-*
 ****/
 module display_converter(
     input logic [4:0] digit, 
@@ -16,6 +16,7 @@ module display_converter(
 localparam ROM_SIZE=32;
 
 //ROM lookup table for seven segment display
+//blanks are unused space we could add characters to. 
 localparam logic [6:0] segment_rom [0:ROM_SIZE-1] = '{
     7'b1111110, //0
     7'b0000110, //1
@@ -54,6 +55,7 @@ localparam logic [6:0] segment_rom [0:ROM_SIZE-1] = '{
     7'b0000000, //blank
     7'b0000000  //blank
 };
+
 //use digit input to index segment_rom lookup table.
 assign segment = segment_rom[digit];
 

design/segment_display/seconds_display.sv

@@ -1,10 +1,11 @@
 /***
-* seconds_display.sv - convert a seconds counter to a seven segement display.
+* seconds_display.sv - converts a five bit seconds counter to its seven segement display equivalent.
 *
 * @author: Dilanthi Prentice, Waylon Cude
 * @date: 6/12/25
 *
 */
+
 module seconds_display
 (
     input [$clog2(60)-1:0] seconds,

doc/bugs.md

@@ -5,6 +5,7 @@
 
 ### Debouncer
 - Logic was fundamentally wrong
+- Found multiple logic bugs with testbench and then assertions
 
 ### Display Converter
 - Found a typo in a single digit

doc/rom_sd.gv

@@ -0,0 +1,23 @@
+digraph rom_sd {
+    Reset [shape = doublecircle, label = "RESET\nbuffer_half = 0\nrom_address = 0\nrom_enable = 1\nbuf.addr=0\nready=0"];
+    node [shape = circle];
+    Delay [label="DELAY\nrom_address++"];
+    WriteBuf [label="WRITEBUF\nbuf.ena=1\nbuf.data=rom_data\nbuf.addr++\nrom_addr++"];
+    EndWrite [label="ENDWRITE\nbuf.ena=1\nbuf.data=rom_data\nbuf.addr++\nready=1"];
+    Wait [label = "WAIT\nbuf.ena=0"];
+
+    Reset -> Reset [label="reset"];
+    Reset -> Delay [label="!reset"];
+
+    Delay -> WriteBuf;
+
+    WriteBuf -> WriteBuf [label="buf.addr < 1023"]
+    WriteBuf -> EndWrite [label="buf.addr == 1023"]
+
+    EndWrite -> Wait;
+
+    Wait -> Wait [label = "buffer_half == buf.address_half"]
+    Wait -> Delay [label = "buffer_half != buf.address_half"]
+
+
+}

lib/audio_buffer_interface.sv

@@ -0,0 +1,18 @@
+interface audio_buffer_interface;
+    logic [10:0] addra;
+    logic [7:0] dina;
+    logic clka;
+    logic ena;
+    logic address_half;
+
+    modport driver (
+        output addra, dina, clka, ena,
+        input address_half
+    );
+
+    modport receiver (
+        input addra, dina, clka, ena,
+        output address_half
+    );
+
+endinterface

verification/segment_display/seconds_display_tb.sv

@@ -1,3 +1,11 @@
+/****
+ * seconds_display_tb.sv - testbench for the seconds_display module.
+ *
+ * @author: Waylon Cude, Dilanthi Prentice
+ * @date: 6/12/2025
+ *
+ * */
+
 `timescale 1ns / 1ps
 module seconds_display_tb;
 int errors = 0;