initial commit

step2.v

@@ -0,0 +1,40 @@
+/**
+ * Step 2: Blinker (slower version)
+ * DONE*
+ */
+
+`default_nettype none
+`include "clockworks.v"
+
+module SOC (
+    input  clk,        // system clock 
+    input  rst_i,      // reset button
+    output [4:0] led, // system LEDs
+    input  RXD,        // UART receive
+    output TXD         // UART transmit
+);
+
+   wire clkI;    // internal clock
+   wire resetn; // internal reset signal, goes low on reset
+   
+   // A blinker that counts on 5 bits, wired to the 5 LEDs
+   reg [4:0] count = 0;
+   always @(posedge clkI) begin
+      count <= !resetn ? 0 : count + 1;
+   end
+
+   // Clock gearbox (to let you see what happens)
+   // and reset circuitry (to workaround an
+   // initialization problem with Ice40)
+   Clockworks #(
+     .SLOW(21) // Divide clock frequency by 2^21
+   )CW(
+     .CLK(clk),
+     .RESET(rst_i),
+     .clk(clkI),
+     .resetn(resetn)
+   );
+   
+   assign led = count;
+   assign TXD  = 1'b0; // not used for now   
+endmodule