Added counter

.gitignore

@@ -5,5 +5,10 @@ devenv.local.nix
 # direnv
 .direnv
 
+*.bak
+obj_dir
+output.vcd
+
+
 # pre-commit
 .pre-commit-config.yaml

README.md

@@ -0,0 +1,12 @@
+# DSB course
+
+## Chapter 4
+
+Minimum number for counter:
+$$
+N(t_{PWM}) = t_{PWM} * f
+$$
+Number of required bits:
+$$
+N = ^2log(N + 1)
+$$

ch4/timebase.sv

@@ -1,8 +1,11 @@
-module timebase 
+`timescale 1ns/1ps
+
+module timebase #(parameter N = 18) 
    (input logic clk,
     input logic reset,
-    output logic [?:0] count);
-
-
+    output logic [N-1:0] count);
 
+  always_ff @(posedge clk, posedge reset)
+    if(reset) count <= 0;
+    else count <= count + 1;
 endmodule

ch4/timebase.sv.bak

@@ -1,5 +0,0 @@
-`timescale 1ns/1ps
-
-Aanpassing van lasse
-
-Aanpassing van Timo

ch4/timebase_tb.sv

@@ -4,7 +4,7 @@ module timebase_tb();
 
    logic clk;
    logic reset;
-   logic [20:0] count;
+   logic [17:0] count;
    
    timebase test (clk, reset, count);
 
@@ -14,8 +14,12 @@ module timebase_tb();
       clk = 0;
 
    initial begin
-          reset = 1; 
-     #10; reset = 0; 
+      $dumpfile("output.vcd");
+      $dumpvars;
+   
+          reset = 0; 
+     #200; reset = 1; 
+      $finish;
    end
 
 endmodule

devenv.nix

@@ -1,22 +1,11 @@
 { pkgs, lib, config, inputs, ... }:
 
 {
-  # https://devenv.sh/basics/
   env.GREET = "devenv";
 
   # https://devenv.sh/packages/
   packages = [ pkgs.verilator pkgs.gtkwave ];
 
-  # https://devenv.sh/languages/
-  # languages.rust.enable = true;
-
-  # https://devenv.sh/processes/
-  # processes.cargo-watch.exec = "cargo-watch";
-
-  # https://devenv.sh/services/
-  # services.postgres.enable = true;
-
-  # https://devenv.sh/scripts/
   scripts.hello.exec = ''
     echo hello from $GREET
   '';