Fix Serial Link

There was a typo in link.v preventing internal clock from working
properly

Gameboy.sv

@@ -599,7 +599,6 @@ gb gb (
 	.serial_data_in(ser_data_in),
 	.serial_clk_out(ser_clk_out),
 	.serial_data_out(ser_data_out),
-	.serial_ena(status[6]),
 	
 	// Palette download will disable cheats option (HPS doesn't distinguish downloads),
 	// so clear the cheats and disable second option (chheats enable/disable)
@@ -808,12 +807,13 @@ wire ser_data_in;
 wire ser_data_out;
 wire ser_clk_in;
 wire ser_clk_out;
+wire serial_ena = status[6];
 
-assign ser_data_in = USER_IN[2];	
-assign USER_OUT[1] = ser_data_out;
+assign ser_data_in = serial_ena ? USER_IN[2] : 1'b1;
+assign USER_OUT[1] = serial_ena ? ser_data_out : 1'b1;
 
-assign ser_clk_in = USER_IN[0];
-assign USER_OUT[0] = sc_int_clock_out?ser_clk_out:1'b1;
+assign ser_clk_in = serial_ena ? USER_IN[0] : 1'b1;
+assign USER_OUT[0] = (serial_ena & sc_int_clock_out) ? ser_clk_out : 1'b1;
 
 
 

rtl/gb.v

@@ -65,7 +65,6 @@ module gb (
 	output         gg_available,
 
 	//serial port
-	input   serial_ena,
 	output sc_int_clock2,
 	input serial_clk_in,
 	output serial_clk_out,
@@ -130,7 +129,7 @@ wire [7:0] cpu_di =
 	   isGBC&&sel_hdma?{hdma_do}:  //hdma GBC
 	   isGBC&&sel_key1?{cpu_speed,6'h3f,prepare_switch}: //key1 cpu speed register(GBC)
 		sel_joy?joy_do:         // joystick register
-		sel_sb?sb:				// serial transfer data register
+		sel_sb?sb_o:				// serial transfer data register
 		sel_sc?sc_r:				// serial transfer control register
 		sel_timer?timer_do:     // timer registers
 		sel_video_reg?video_do: // video registers
@@ -260,16 +259,11 @@ gbc_snd audio (
 // -----------------------serial port()--------------------------------
 // --------------------------------------------------------------------
 
-wire serial_irq    = serial_ena ? serial_irq_s    : serial_irq_f;
-wire [7:0] sb      = serial_ena ? sb_s            : 8'hFF;
-wire sc_start      = serial_ena ? sc_start_s      : sc_start_f;
-wire sc_shiftclock = serial_ena ? sc_shiftclock_s : sc_shiftclock_f;
-
 // SNAC
-wire serial_irq_s;
-wire [7:0] sb_s;
-wire sc_start_s;
-wire sc_shiftclock_s;
+wire serial_irq;
+wire [7:0] sb_o;
+wire sc_start;
+wire sc_shiftclock;
 
 assign sc_int_clock2 = sc_shiftclock;
 
@@ -290,50 +284,13 @@ link link (
 
   .serial_clk_out(serial_clk_out),
   .serial_data_out(serial_data_out),
-  .sb(sb_s),
-  .serial_irq(serial_irq_s),
-  .sc_start(sc_start_s),
-  .sc_int_clock(sc_shiftclock_s)
+  .sb(sb_o),
+  .serial_irq(serial_irq),
+  .sc_start(sc_start),
+  .sc_int_clock(sc_shiftclock)
 
 );
 
-// Fake
-reg sc_start_f,sc_shiftclock_f;
-reg serial_irq_f;
-
-always @(posedge clk_cpu) begin
-	reg [3:0] serial_counter;
-	reg [8:0] serial_clk_div; //8192Hz
-
-	serial_irq_f <= 1'b0;
-   if(reset_r) begin
-		  sc_start_f <= 1'b0;
-		  sc_shiftclock_f <= 1'b0;
-	end else if (sel_sc && !cpu_wr_n) begin	 //cpu write
-		sc_start_f <= cpu_do[7];
-		sc_shiftclock_f <= cpu_do[0];
-		if (cpu_do[7]) begin 						//enable transfer
-			serial_clk_div <= 9'h1FF;
-			serial_counter <= 4'd8;
-		end 
-	end else if (sc_start_f && sc_shiftclock_f) begin // serial transfer and serial clock enabled
-		
-		serial_clk_div <= serial_clk_div - 9'd1;
-		
-		if (serial_clk_div == 9'd0  && serial_counter)
-				serial_counter <= serial_counter - 4'd1;
-		
-		if (!serial_counter) begin
-			serial_irq_f <= 1'b1; 	//trigger interrupt
-			sc_start_f <= 1'b0; 	//reset transfer state
-			serial_clk_div <= 9'h1FF;
-		   serial_counter <= 4'd8;
-		end	
-	
-	end
-	
-end
-
 // --------------------------------------------------------------------
 // ------------------------------ inputs ------------------------------
 // --------------------------------------------------------------------

rtl/link.v

@@ -69,7 +69,7 @@ always @(posedge clk) begin
          serial_clk_div <= serial_clk_div - 9'd1;
 
          if (serial_counter != 0) begin
-            if (serial_clk_div == {1'b0,CLK_DIV[8:1]+1'd1}) begin
+            if (serial_clk_div == CLK_DIV/2+1) begin
                serial_clk_out_r <= ~serial_clk_out_r;
                serial_out_r <= sb[7];
             end else if (!serial_clk_div) begin