Add public domain FPGA files for Xilinx s3/s3e

2 files changed, 2364 insertions, 0 deletions

diff --git a/fpga/xilinx/digilent/spartan_3/remote_access.v b/fpga/xilinx/digilent/spartan_3/remote_access.v
new file mode 100644
index 0000000..4a42a61
--- /dev/null
+++ b/fpga/xilinx/digilent/spartan_3/remote_access.v
@@ -0,0 +1,1180 @@
+`timescale 1ns / 1ps
+//////////////////////////////////////////////////////////////////////////////////
+// Company: 			Pearson Computing
+// Engineer: 			Timothy Pearson
+// 
+// Create Date:    	11:58:21 07/07/2007 
+// Design Name:		Remote Access Driver
+// Module Name:    	remote_access 
+// Project Name: 		Remote Access Driver
+// Target Devices: 	Digilent Spartan 3E Development Board
+// Tool versions: 	Xilinx ISE v9.1 SP3
+// Description: 		Serial remote access driver and LCD display driver
+//
+// Dependencies: 
+//
+// Revision: 
+// Revision 0.01 - File Created
+// Additional Comments: Released into the Public Domain
+//
+//////////////////////////////////////////////////////////////////////////////////
+module remote_access(
+	input main_fifty_clock,								// 50MHz clock in
+	input [3:0] remote_access_4_bit_output,		// 4 bit output from the user program to remote access client
+	output [3:0] remote_access_4_bit_input,		// 4 bit input from the remote access client to user program
+	input [7:0] remote_access_8_bit_output,		// 8 bit output from the user program to remote access client
+	output [7:0] remote_access_8_bit_input,		// 8 bit input from the remote access client to user program
+	input [15:0] remote_access_16_bit_output,	// 16 bit output from the user program to the remote access client
+	output [15:0] remote_access_16_bit_input,	// 16 bit input from the remote access client to the user program 
+	input serial_port_receiver,
+	output serial_port_transmitter,
+	input remote_access_input_enable,
+	input [7:0] local_input,
+	input seize_serial_tx,
+	input [7:0] serial_tx_data,
+	input serial_tx_strobe,
+	output [7:0] serial_rx_data,
+	output serial_rx_strobe,
+	input [5:0] lcd_data_in_address,
+	input [7:0] lcd_data_in_data,
+	input lcd_data_in_enable,
+	input sram_wren_in,
+	input sram_clock_in,
+	input [7:0] sram_data_in,
+	input [13:0] sram_address_in,
+	output [7:0] sram_data_out,
+	output sram_available,
+	input sram_processing_done,
+	input [7:0] led_segment_bus,
+	input [3:0] led_digit_select);
+	
+	reg [7:0] remote_access_4_bit_input_reg;
+	reg [7:0] remote_access_8_bit_input_reg;
+	reg [15:0] remote_access_16_bit_input_reg;
+	reg [3:0] remote_access_lcd_data_out_reg;
+	reg remote_access_lcd_rs_out_reg;
+	reg remote_access_lcd_rw_out_reg;
+	reg remote_access_lcd_enable_out_reg;
+	reg [7:0] serial_rx_data_reg;
+	reg serial_rx_strobe_reg;
+	reg sram_available_reg;
+	reg startup_needed = 1;
+	
+	assign remote_access_4_bit_input = remote_access_4_bit_input_reg;
+	assign remote_access_8_bit_input = remote_access_8_bit_input_reg;
+	assign remote_access_16_bit_input = remote_access_16_bit_input_reg;
+	assign remote_access_lcd_data_out = remote_access_lcd_data_out_reg;
+	assign remote_access_lcd_rs_out = remote_access_lcd_rs_out_reg;
+	assign remote_access_lcd_rw_out = remote_access_lcd_rw_out_reg;
+	assign remote_access_lcd_enable_out = remote_access_lcd_enable_out_reg;
+	assign serial_rx_data = serial_rx_data_reg;
+	assign serial_rx_strobe = serial_rx_strobe_reg;
+	assign sram_available = sram_available_reg;
+	
+	//-----------------------------------------------------------------------------------
+	//
+	// Create a 4.16MHz clock for the LCD display driver and a 25MHz clock 
+	// for the serial receiver.
+	//
+	//-----------------------------------------------------------------------------------
+	
+	reg four_mhz_clk;
+	reg clk_div_by_two;
+	reg clk_div_by_four;
+	reg clk_div_by_eight;
+	reg [3:0] fifty_clock_divider = 0;
+	
+	always @(posedge main_fifty_clock) begin
+		fifty_clock_divider = fifty_clock_divider + 1;
+		if (fifty_clock_divider > 12) begin
+			four_mhz_clk = !four_mhz_clk;
+			fifty_clock_divider = 0;
+		end
+	end
+	
+	always @(posedge main_fifty_clock) begin
+		clk_div_by_two = !clk_div_by_two;
+	end
+	
+	always @(posedge clk_div_by_two) begin
+		clk_div_by_four = !clk_div_by_four;
+	end
+	
+	always @(posedge clk_div_by_four) begin
+		clk_div_by_eight = !clk_div_by_eight;
+	end
+	
+	//-----------------------------------------------------------------------------------
+	//
+	// Keep track of what is on the LED display
+	//
+	//-----------------------------------------------------------------------------------
+	
+	reg [7:0] led_display_bytes [3:0];
+	reg [4:0] digit_blanker_1 = 0;
+	reg [4:0] digit_blanker_2 = 0;
+	reg [4:0] digit_blanker_3 = 0;
+	reg [4:0] digit_blanker_4 = 0;
+	
+	always @(negedge clk_div_by_eight) begin
+		if (led_digit_select[0] == 0) begin
+			led_display_bytes[0] = led_segment_bus;
+			digit_blanker_1 = 0;
+		end
+		
+		if (led_digit_select[1] == 0) begin
+			led_display_bytes[1] = led_segment_bus;
+			digit_blanker_2 = 0;
+		end
+		
+		if (led_digit_select[2] == 0) begin
+			led_display_bytes[2] = led_segment_bus;
+			digit_blanker_3 = 0;
+		end
+		
+		if (led_digit_select[3] == 0) begin
+			led_display_bytes[3] = led_segment_bus;
+			digit_blanker_4 = 0;
+		end
+		
+		if (digit_blanker_1 > 30) begin
+			led_display_bytes[0] = 255;
+		end
+		
+		if (digit_blanker_2 > 30) begin
+			led_display_bytes[1] = 255;
+		end
+		
+		if (digit_blanker_3 > 30) begin
+			led_display_bytes[2] = 255;
+		end
+		
+		if (digit_blanker_4 > 30) begin
+			led_display_bytes[3] = 255;
+		end
+	end
+	
+	//-----------------------------------------------------------------------------------
+	//
+	// Instantiate the data storage RAM for signal processing
+	//
+	//-----------------------------------------------------------------------------------
+
+	reg data_storage_remote_enable = 0;
+	wire data_storage_clka;
+	wire [7:0] data_storage_dina;
+	wire [13:0] data_storage_addra;
+	wire data_storage_write_enable;
+	wire [7:0] data_storage_data_out;
+	
+	reg [7:0] data_storage_dina_reg;
+	reg [13:0] data_storage_addra_reg;
+	reg data_storage_write_enable_reg;
+
+	data_storage data_storage(.clka(data_storage_clka), .dina(data_storage_dina), .addra(data_storage_addra), 
+		.wea(data_storage_write_enable), .douta(data_storage_data_out));
+	
+	assign data_storage_clka = (data_storage_remote_enable) ? main_fifty_clock : sram_clock_in;
+	assign data_storage_dina = (data_storage_remote_enable) ? data_storage_dina_reg : sram_data_in;
+	assign data_storage_addra = (data_storage_remote_enable) ? data_storage_addra_reg : sram_address_in;
+	assign data_storage_write_enable = (data_storage_remote_enable) ? data_storage_write_enable_reg : sram_wren_in;
+	
+	assign sram_data_out = data_storage_data_out;
+	
+	// -----------------------------------------------------------------------------------------------
+	//
+	// Here is the serial receiver and transmitter
+	//
+	// -----------------------------------------------------------------------------------------------
+
+	reg [7:0] transmit_all_data_state = 0;
+
+	wire RxD_data_ready;
+	wire [7:0] RxD_data;
+	wire RxD_endofpacket;
+	wire RxD_idle;
+
+	reg TxD_start;
+	reg [7:0] TxD_data;
+	wire TxD_busy;
+	wire [4:0] state;
+	
+	reg [7:0] transmitter_4_bit_state = 0;
+	reg [7:0] transmitter_8_bit_state = 0;
+	reg [15:0] transmitter_16_bit_state = 0;
+	reg [7:0] transmitter_main_state = 0;
+	reg [7:0] transmitter_input_state = 0;
+
+	async_transmit asyncTX(.clk(clk_div_by_two), .TxD_start(TxD_start), .TxD_data(TxD_data), .TxD(serial_port_transmitter), .TxD_busy(TxD_busy), .state(state));
+	async_receiver asyncRX(.clk(clk_div_by_two), .RxD(serial_port_receiver), .RxD_data_ready(RxD_data_ready), .RxD_data(RxD_data), .RxD_endofpacket(RxD_endofpacket), .RxD_idle(RxD_idle));
+
+	reg tx_toggle = 0;
+	
+	reg transmit_4_bit_status = 0;
+	reg transmit_4_bit_status_done = 0;
+	
+	reg transmit_8_bit_status = 0;
+	reg transmit_8_bit_status_done = 0;
+	
+	reg transmit_16_bit_status = 0;
+	reg transmit_16_bit_pass_two = 0;
+	reg transmit_16_bit_status_done = 0;
+	
+	reg transmit_main_status = 0;
+	reg transmit_main_status_done = 0;
+	
+	reg transmit_input_status = 0;
+	reg transmit_input_status_done = 0;
+	
+	reg transmit_lcd_status = 0;
+	reg transmit_lcd_status_done = 0;
+	reg [7:0] transmit_lcd_status_counter = 0;
+	
+	reg enable_remote_access_input = 1;
+	reg remote_access_input_enable_prev = 0;
+	reg prev_was_carriage_return = 0;
+	
+	reg [7:0] lcd_display_string [31:0];
+	
+	reg transmit_dsp_status = 0;
+	reg transmit_dsp_status_done = 0;
+	reg transmit_dsp_status_holdoff = 0;
+	reg [15:0] transmit_dsp_status_counter = 0;
+	
+	reg transmit_led_status = 0;
+	reg transmit_led_status_done = 0;
+	reg [7:0] transmit_led_status_counter = 0;
+	
+	// Transmit!	
+	always @(posedge clk_div_by_two) begin
+		transmitter_4_bit_state = remote_access_4_bit_output;
+		transmitter_8_bit_state = remote_access_8_bit_output;
+		transmitter_16_bit_state = remote_access_16_bit_output;
+		
+		transmitter_main_state = 0;
+		transmitter_main_state[0] = enable_remote_access_input;
+		
+		transmitter_input_state = local_input;
+	
+		if (seize_serial_tx == 1) begin
+			TxD_start = serial_tx_strobe;
+			TxD_data = serial_tx_data;
+		end else begin
+			if (tx_toggle == 0) begin
+				if ((transmit_4_bit_status == 1) && (transmit_4_bit_status_done == 0)) begin
+					TxD_data = transmitter_4_bit_state;
+												
+					TxD_start = 1;
+					tx_toggle = 1;
+					
+					transmit_4_bit_status_done = 1;
+				end
+				
+				if ((transmit_8_bit_status == 1) && (transmit_8_bit_status_done == 0)) begin
+					TxD_data = transmitter_8_bit_state;
+												
+					TxD_start = 1;
+					tx_toggle = 1;
+					
+					transmit_8_bit_status_done = 1;
+				end
+				
+				if ((transmit_16_bit_status == 1) && (transmit_16_bit_status_done == 0)) begin
+					if (transmit_16_bit_pass_two == 0) begin
+						TxD_data = transmitter_16_bit_state[15:8];
+						
+						TxD_start = 1;
+						tx_toggle = 1;	
+						
+						transmit_16_bit_pass_two = 1;
+					end else begin
+						TxD_data = transmitter_16_bit_state[7:0];
+						
+						TxD_start = 1;
+						tx_toggle = 1;	
+						
+						transmit_16_bit_status_done = 1;
+					end
+				end
+				
+				if ((transmit_main_status == 1) && (transmit_main_status_done == 0)) begin
+					TxD_data = transmitter_main_state;
+												
+					TxD_start = 1;
+					tx_toggle = 1;
+					
+					transmit_main_status_done = 1;
+				end
+				
+				if ((transmit_input_status == 1) && (transmit_input_status_done == 0)) begin
+					TxD_data = transmitter_input_state;
+												
+					TxD_start = 1;
+					tx_toggle = 1;
+					
+					transmit_input_status_done = 1;
+				end
+				
+				if ((transmit_lcd_status == 1) && (transmit_lcd_status_done == 0)) begin
+					TxD_data = lcd_display_string[transmit_lcd_status_counter];
+												
+					TxD_start = 1;
+					tx_toggle = 1;
+					
+					transmit_lcd_status_counter = transmit_lcd_status_counter + 1;
+					if (transmit_lcd_status_counter > 31) begin
+						transmit_lcd_status_done = 1;
+					end
+				end
+				
+				if ((transmit_led_status == 1) && (transmit_led_status_done == 0)) begin
+					TxD_data = led_display_bytes[transmit_led_status_counter];
+												
+					TxD_start = 1;
+					tx_toggle = 1;
+					
+					transmit_led_status_counter = transmit_led_status_counter + 1;
+					if (transmit_led_status_counter > 3) begin
+						transmit_led_status_done = 1;
+					end
+				end
+				
+				if ((transmit_dsp_status == 1) && (transmit_dsp_status_done == 0)) begin
+					if (transmit_dsp_status_holdoff == 0) begin
+						transmit_dsp_status_holdoff = 1;
+						data_storage_write_enable_reg = 0;
+						data_storage_addra_reg = 0;			// Initial data value
+					end else begin
+						data_storage_write_enable_reg = 0;
+						TxD_data = data_storage_data_out;
+													
+						TxD_start = 1;
+						tx_toggle = 1;
+						
+						transmit_dsp_status_counter = transmit_dsp_status_counter + 1;
+						data_storage_addra_reg = transmit_dsp_status_counter;
+						if (transmit_dsp_status_counter > 16384) begin
+							transmit_dsp_status_done = 1;
+							data_storage_write_enable_reg = 1'bz;
+							data_storage_addra_reg = 14'bz;
+						end
+					end
+				end
+			end else begin
+				if (state == 5'b10000) begin	// Wait for transmission of byte to complete
+					TxD_start = 0;
+					tx_toggle = 0;
+				end
+			end
+		end
+		
+		if (transmit_4_bit_status == 0) begin
+			transmit_4_bit_status_done = 0;
+		end
+		
+		if (transmit_8_bit_status == 0) begin
+			transmit_8_bit_status_done = 0;
+		end
+		
+		if (transmit_16_bit_status == 0) begin
+			transmit_16_bit_pass_two = 0;
+			transmit_16_bit_status_done = 0;
+		end
+		
+		if (transmit_main_status == 0) begin
+			transmit_main_status_done = 0;
+		end
+		
+		if (transmit_input_status == 0) begin
+			transmit_input_status_done = 0;
+		end
+		
+		if (transmit_lcd_status == 0) begin
+			transmit_lcd_status_done = 0;
+			transmit_lcd_status_counter = 0;
+		end
+		
+		if (transmit_led_status == 0) begin
+			transmit_led_status_done = 0;
+			transmit_led_status_counter = 0;
+		end
+		
+		if (transmit_dsp_status == 0) begin
+			transmit_dsp_status_done = 0;
+			transmit_dsp_status_holdoff = 0;
+			transmit_dsp_status_counter = 0;
+		end
+	end
+
+	reg [7:0] lcd_display_initialization_state = 0;
+	reg serial_character_received = 0;
+	reg [7:0] serial_receiver_toggler = 0;
+	reg [7:0] serial_command_buffer = 0;
+	reg [2:0] next_byte_is_command = 0;
+	reg [7:0] next_byte_is_command_prev_command = 0;
+	reg [7:0] serial_command_timer = 0;
+	reg update_lcd_display = 0;
+	reg [7:0] serial_update_counter = 0;
+	reg [15:0] dsp_update_counter = 0;
+	reg [7:0] received_lcd_display_string [31:0];
+	reg data_write_timer = 0;
+	reg waiting_on_dsp_processing = 0;
+	
+	// Receive serial commands
+	always @(posedge clk_div_by_two) begin
+		if (startup_needed == 1) begin
+			startup_needed = 0;
+			transmit_dsp_status = 1;
+		end
+	
+		if (lcd_data_in_enable == 1) begin
+			received_lcd_display_string[lcd_data_in_address] = lcd_data_in_data;
+			update_lcd_display = 1;
+			serial_command_timer = 255;
+		end
+	
+		if ((remote_access_input_enable == 1) && (remote_access_input_enable_prev == 0)) begin
+			enable_remote_access_input = !enable_remote_access_input;
+		end
+		remote_access_input_enable_prev = remote_access_input_enable;
+	
+		if (enable_remote_access_input == 0) begin
+			// Enable local input
+			remote_access_8_bit_input_reg = local_input;
+		end
+	
+		if (serial_command_timer > 0) begin
+			serial_command_timer = serial_command_timer - 1;
+		end else begin
+			update_lcd_display = 0;
+		end
+		
+		if (transmit_4_bit_status_done == 1) begin
+			transmit_4_bit_status = 0;
+			if (transmit_all_data_state == 1) begin
+				transmit_8_bit_status = 1;
+			end
+		end
+		
+		if (transmit_8_bit_status_done == 1) begin
+			transmit_8_bit_status = 0;
+			if (transmit_all_data_state == 1) begin
+				transmit_16_bit_status = 1;
+			end
+		end
+		
+		if (transmit_16_bit_status_done == 1) begin
+			transmit_16_bit_status = 0;
+			if (transmit_all_data_state == 1) begin
+				transmit_led_status = 1;
+			end
+		end
+		
+		if (transmit_led_status_done == 1) begin
+			transmit_led_status = 0;
+			if (transmit_all_data_state == 1) begin
+				transmit_all_data_state = 0;
+			end
+		end
+		
+		if (transmit_main_status_done == 1) begin
+			transmit_main_status = 0;
+			if (transmit_all_data_state == 1) begin
+				transmit_4_bit_status = 1;
+			end
+		end
+		
+		if (transmit_input_status_done == 1) begin
+			transmit_input_status = 0;
+		end
+		
+		if (transmit_lcd_status_done == 1) begin
+			transmit_lcd_status = 0;
+			if (transmit_all_data_state == 1) begin
+				transmit_main_status = 1;
+			end
+		end
+		
+		if (transmit_dsp_status_done == 1) begin
+			transmit_dsp_status = 0;
+			data_storage_remote_enable = 0;
+		end
+		
+		if (transmit_dsp_status == 1) begin
+			data_storage_remote_enable = 1;
+		end
+		
+		if (data_write_timer > 1) begin
+			data_write_timer = data_write_timer - 1;
+		end else begin
+			if (data_write_timer == 1) begin
+				data_storage_write_enable_reg = 0;
+				data_write_timer = 0;
+			end
+		end
+		
+		if ((waiting_on_dsp_processing == 1) && (sram_processing_done == 1)) begin
+			waiting_on_dsp_processing = 0;
+			transmit_dsp_status = 1;
+		end
+	
+		serial_rx_strobe_reg = 0;		// Make sure that this get reset!
+		
+		if ((sram_processing_done == 1) && (sram_available_reg == 1)) begin
+			sram_available_reg = 0;
+			transmit_dsp_status = 1;
+		end
+	
+		if (RxD_data_ready == 1) begin		
+			if (serial_character_received == 0) begin
+				serial_rx_data_reg = RxD_data;
+				serial_rx_strobe_reg = 1;		// Signal new data...
+				if (seize_serial_tx == 0) begin
+					// Parse the command and see what it is
+					serial_character_received = 1;
+					if (RxD_data == 13) begin
+						// Carriage Return!  The serial_command_buffer holds the command!  Parse it!
+						if (next_byte_is_command == 0) begin
+							if (serial_command_buffer == 65) begin
+								// Display update requested
+								next_byte_is_command = 1;
+								serial_update_counter = 0;
+								next_byte_is_command_prev_command = 65;
+							end
+							
+							if (serial_command_buffer == 66) begin
+								// 8 bit input update
+								if (enable_remote_access_input == 1) begin
+									next_byte_is_command = 1;
+									serial_update_counter = 0;
+									next_byte_is_command_prev_command = 66;
+								end
+							end
+							
+							if (serial_command_buffer == 67) begin
+								// 16 bit input update
+								next_byte_is_command = 1;
+								serial_update_counter = 0;
+								next_byte_is_command_prev_command = 67;
+							end
+							
+							if (serial_command_buffer == 68) begin
+								// 8 bit output status
+								transmit_8_bit_status = 1;
+							end
+							
+							if (serial_command_buffer == 69) begin
+								// 16 bit output status
+								transmit_16_bit_status = 1;
+							end
+							
+							if (serial_command_buffer == 70) begin
+								// System status
+								transmit_main_status = 1;
+							end
+							
+							if (serial_command_buffer == 71) begin
+								// Simulate center button press
+								enable_remote_access_input = !enable_remote_access_input;
+							end
+							
+							if (serial_command_buffer == 72) begin
+								// Local input status
+								transmit_input_status = 1;
+							end
+							
+							if (serial_command_buffer == 73) begin
+								// 4 bit input update
+								if (enable_remote_access_input == 1) begin
+									next_byte_is_command = 1;
+									serial_update_counter = 0;
+									next_byte_is_command_prev_command = 73;
+								end
+							end
+							
+							if (serial_command_buffer == 74) begin
+								// 4 bit output status
+								transmit_4_bit_status = 1;
+							end
+							
+							if (serial_command_buffer == 75) begin
+								// Transmit the contents of the LCD...
+								transmit_lcd_status = 1;
+							end
+							
+							if (serial_command_buffer == 76) begin
+								// Transmit the contents of the LCD...
+								transmit_all_data_state = 1;
+								transmit_lcd_status = 1;
+							end
+							
+							if (serial_command_buffer == 77) begin
+								// Receive offline DSP data
+								next_byte_is_command = 1;
+								dsp_update_counter = 0;
+								next_byte_is_command_prev_command = 77;
+							end
+							
+							if (serial_command_buffer == 78) begin
+								// Transmit the contents of RAM...
+								transmit_dsp_status = 1;
+							end
+						end else begin														
+							if (next_byte_is_command == 1) begin
+								// The previous byte was the command--now load in the data!
+								if (next_byte_is_command_prev_command == 65) begin
+									if (serial_update_counter < 32) begin
+										received_lcd_display_string[serial_update_counter] = serial_command_buffer;
+										serial_update_counter = serial_update_counter + 1;
+									end else begin
+										update_lcd_display = 1;
+										serial_command_timer = 255;
+										next_byte_is_command = 0;
+									end
+								end
+								
+								// 4 bit input update
+								if (next_byte_is_command_prev_command == 73) begin
+									remote_access_4_bit_input_reg = serial_command_buffer;
+									next_byte_is_command = 0;
+								end
+								
+								// 8 bit input update
+								if (next_byte_is_command_prev_command == 66) begin
+									remote_access_8_bit_input_reg = serial_command_buffer;
+									next_byte_is_command = 0;
+								end
+								
+								// 16 bit input update
+								if (next_byte_is_command_prev_command == 67) begin
+									if (serial_update_counter == 0) begin
+										remote_access_16_bit_input_reg[15:8] = serial_command_buffer;
+										serial_update_counter = 1;
+									end else begin
+										remote_access_16_bit_input_reg[7:0] = serial_command_buffer;
+										next_byte_is_command = 0;
+									end
+								end
+								
+								// DSP input data
+								if (next_byte_is_command_prev_command == 77) begin
+									if (dsp_update_counter < 16384) begin
+										data_storage_remote_enable = 1;
+										data_storage_addra_reg = dsp_update_counter;
+										data_storage_dina_reg = serial_command_buffer;
+										data_storage_write_enable_reg = 1;
+										data_write_timer = 3;
+										dsp_update_counter = dsp_update_counter + 1;
+										
+										// TESTING ONLY!!!
+										//if (dsp_update_counter < 17) begin
+										//	received_lcd_display_string[dsp_update_counter - 1] = serial_command_buffer;
+										//end
+									end else begin
+										next_byte_is_command = 0;
+										data_storage_write_enable_reg = 0;
+										data_storage_remote_enable = 0;
+										sram_available_reg = 1;
+										data_storage_write_enable_reg = 1'bz;
+										data_storage_addra_reg = 14'bz;
+										waiting_on_dsp_processing = 1;
+										
+										// TESTING ONLY!!!
+										//transmit_dsp_status = 1;
+									end
+								end
+							end
+						end
+					end
+				end
+				
+				//if (RxD_data != 10) begin		// Ignore linefeeds
+					serial_command_buffer = RxD_data;
+				//end
+				
+				if (RxD_data == 13) begin
+					prev_was_carriage_return = 1;
+				end else begin
+					prev_was_carriage_return = 0;
+				end
+			
+				serial_receiver_toggler = serial_receiver_toggler + 1;
+			end
+		end
+		
+		if (RxD_data_ready == 0) begin
+			serial_character_received = 0;
+		end
+	end
+	
+	//-----------------------------------------------------------------------------------
+	//
+	// This routine will display the contents of lcd_display_string on the LCD display
+	//
+	//-----------------------------------------------------------------------------------
+	
+	reg [15:0] lcd_display_wait_counter = 0;
+	reg [7:0] lcd_display_current_character = 0;
+	reg lcd_display_line_two = 0;		// Are we trying to write to line two?
+	
+	always @(posedge four_mhz_clk) begin	
+		case (lcd_display_initialization_state)
+			// Initialize the display according to the reference manual
+			0:begin
+				// Set up the default display...
+				lcd_display_string[0] = 73;		// I
+				lcd_display_string[1] = 110;		// n
+				lcd_display_string[2] = 105;		// i
+				lcd_display_string[3] = 116;		// t
+				lcd_display_string[4] = 105;		// i
+				lcd_display_string[5] = 97;		// a
+				lcd_display_string[6] = 108;		// l
+				lcd_display_string[7] = 105;		// i
+				lcd_display_string[8] = 122;		// z
+				lcd_display_string[9] = 97;		// a
+				lcd_display_string[10] = 116;	// t
+				lcd_display_string[11] = 105;	// i
+				lcd_display_string[12] = 111;	// o
+				lcd_display_string[13] = 110;	// n
+				lcd_display_string[14] = 32;		// <blank>
+				lcd_display_string[15] = 32;		// <blank>
+				lcd_display_string[16] = 79;		// O
+				lcd_display_string[17] = 75;		// k
+				lcd_display_string[18] = 32;		// <blank>
+				lcd_display_string[19] = 32;		// <blank>
+				lcd_display_string[20] = 32;		// <blank>
+				lcd_display_string[21] = 32;		// <blank>
+				lcd_display_string[22] = 32;		// <blank>
+				lcd_display_string[23] = 32;		// <blank>
+				lcd_display_string[24] = 32;		// <blank>
+				lcd_display_string[25] = 32;		// <blank>
+				lcd_display_string[26] = 32;		// <blank>
+				lcd_display_string[27] = 32;		// <blank>
+				lcd_display_string[28] = 32;		// <blank>
+				lcd_display_string[29] = 32;		// <blank>
+				lcd_display_string[30] = 32;		// <blank>
+				lcd_display_string[31] = 32;		// <blank>
+			
+				lcd_display_current_character = 0;
+				
+				lcd_display_line_two = 0;
+				remote_access_lcd_data_out_reg = 3;
+				remote_access_lcd_enable_out_reg = 1;
+				remote_access_lcd_rs_out_reg = 0;
+				remote_access_lcd_rw_out_reg = 0;
+				lcd_display_wait_counter = 17083;	// Wait 15mS
+				lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			1:begin
+				remote_access_lcd_enable_out_reg = 0;
+				lcd_display_wait_counter = lcd_display_wait_counter - 1;
+				if (lcd_display_wait_counter == 0) lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			2:begin
+				remote_access_lcd_data_out_reg = 3;
+				remote_access_lcd_enable_out_reg = 1;
+				lcd_display_wait_counter = 417;		// Wait 100uS
+				lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			3:begin
+				remote_access_lcd_enable_out_reg = 0;
+				lcd_display_wait_counter = lcd_display_wait_counter - 1;
+				if (lcd_display_wait_counter == 0) lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			4:begin
+				remote_access_lcd_data_out_reg = 3;
+				remote_access_lcd_enable_out_reg = 1;
+				lcd_display_wait_counter = 167;		// Wait 40uS
+				lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			5:begin
+				remote_access_lcd_enable_out_reg = 0;
+				lcd_display_wait_counter = lcd_display_wait_counter - 1;
+				if (lcd_display_wait_counter == 0) lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			6:begin
+				remote_access_lcd_data_out_reg = 2;
+				remote_access_lcd_enable_out_reg = 1;
+				lcd_display_wait_counter = 167;		// Wait 40uS
+				lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			7:begin
+				remote_access_lcd_enable_out_reg = 0;
+				lcd_display_wait_counter = lcd_display_wait_counter - 1;
+				if (lcd_display_wait_counter == 0) lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			// Display is now initialized
+			
+			// Send Function Set command
+			8:begin
+				remote_access_lcd_data_out_reg = 2;
+				remote_access_lcd_enable_out_reg = 1;
+				lcd_display_wait_counter = 5;		// Wait 1uS
+				lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			9:begin
+				remote_access_lcd_enable_out_reg = 0;
+				lcd_display_wait_counter = lcd_display_wait_counter - 1;
+				if (lcd_display_wait_counter == 0) lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			10:begin
+				remote_access_lcd_data_out_reg = 8;
+				remote_access_lcd_enable_out_reg = 1;
+				lcd_display_wait_counter = 167;		// Wait 40uS
+				lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			11:begin
+				remote_access_lcd_enable_out_reg = 0;
+				lcd_display_wait_counter = lcd_display_wait_counter - 1;
+				if (lcd_display_wait_counter == 0) lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			
+			// Send Entry Mode Set command
+			12:begin
+				remote_access_lcd_data_out_reg = 0;
+				remote_access_lcd_enable_out_reg = 1;
+				lcd_display_wait_counter = 5;		// Wait 1uS
+				lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			13:begin
+				remote_access_lcd_enable_out_reg = 0;
+				lcd_display_wait_counter = lcd_display_wait_counter - 1;
+				if (lcd_display_wait_counter == 0) lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			14:begin
+				remote_access_lcd_data_out_reg = 6;
+				remote_access_lcd_enable_out_reg = 1;
+				lcd_display_wait_counter = 167;		// Wait 40uS
+				lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			15:begin
+				remote_access_lcd_enable_out_reg = 0;
+				lcd_display_wait_counter = lcd_display_wait_counter - 1;
+				if (lcd_display_wait_counter == 0) lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			
+			// Send Display On command and disable cursors and blinking
+			16:begin
+				remote_access_lcd_data_out_reg = 0;
+				remote_access_lcd_enable_out_reg = 1;
+				lcd_display_wait_counter = 5;		// Wait 1uS
+				lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			17:begin
+				remote_access_lcd_enable_out_reg = 0;
+				lcd_display_wait_counter = lcd_display_wait_counter - 1;
+				if (lcd_display_wait_counter == 0) lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			18:begin
+				remote_access_lcd_data_out_reg = 12;
+				remote_access_lcd_enable_out_reg = 1;
+				lcd_display_wait_counter = 167;		// Wait 40uS
+				lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			19:begin
+				remote_access_lcd_enable_out_reg = 0;
+				lcd_display_wait_counter = lcd_display_wait_counter - 1;
+				if (lcd_display_wait_counter == 0) lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			
+			// Send Clear Display command
+			20:begin
+				remote_access_lcd_data_out_reg = 0;
+				remote_access_lcd_enable_out_reg = 1;
+				lcd_display_wait_counter = 5;		// Wait 1uS
+				lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			21:begin
+				remote_access_lcd_enable_out_reg = 0;
+				lcd_display_wait_counter = lcd_display_wait_counter - 1;
+				if (lcd_display_wait_counter == 0) lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			22:begin
+				remote_access_lcd_data_out_reg = 1;
+				remote_access_lcd_enable_out_reg = 1;
+				lcd_display_wait_counter = 6833;		// Wait 1.64uS
+				lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			23:begin
+				remote_access_lcd_enable_out_reg = 0;
+				lcd_display_wait_counter = lcd_display_wait_counter - 1;
+				if (lcd_display_wait_counter == 0) lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			
+			// Set DD RAM Address to 0 if lcd_display_line_two is 0, or 0x40 if it is 1
+			24:begin
+				remote_access_lcd_rs_out_reg = 0;
+				if (lcd_display_line_two == 0) begin
+					remote_access_lcd_data_out_reg = 8;
+				end
+				if (lcd_display_line_two == 1) begin
+					remote_access_lcd_data_out_reg = 12;
+				end
+				remote_access_lcd_enable_out_reg = 1;
+				lcd_display_wait_counter = 5;		// Wait 1uS
+				lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			25:begin
+				remote_access_lcd_enable_out_reg = 0;
+				lcd_display_wait_counter = lcd_display_wait_counter - 1;
+				if (lcd_display_wait_counter == 0) lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			26:begin
+				remote_access_lcd_data_out_reg = 0;
+				remote_access_lcd_enable_out_reg = 1;
+				lcd_display_wait_counter = 167;		// Wait 40uS
+				lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			27:begin
+				remote_access_lcd_enable_out_reg = 0;
+				lcd_display_wait_counter = lcd_display_wait_counter - 1;
+				if (lcd_display_wait_counter == 0) lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			
+			// Display the characters
+			28:begin
+				remote_access_lcd_data_out_reg = lcd_display_string[lcd_display_current_character][7:4];
+				remote_access_lcd_rs_out_reg = 1;
+				remote_access_lcd_enable_out_reg = 1;
+				lcd_display_wait_counter = 5;		// Wait 1uS
+				lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			29:begin
+				remote_access_lcd_enable_out_reg = 0;
+				lcd_display_wait_counter = lcd_display_wait_counter - 1;
+				if (lcd_display_wait_counter == 0) lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			30:begin
+				remote_access_lcd_data_out_reg = lcd_display_string[lcd_display_current_character][3:0];
+				remote_access_lcd_enable_out_reg = 1;
+				lcd_display_wait_counter = 167;		// Wait 40uS
+				lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			31:begin
+				remote_access_lcd_enable_out_reg = 0;
+				lcd_display_wait_counter = lcd_display_wait_counter - 1;
+				if (lcd_display_wait_counter == 0) lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			32:begin
+				lcd_display_current_character = lcd_display_current_character + 1;
+				lcd_display_initialization_state = lcd_display_initialization_state + 1;
+				if (lcd_display_current_character < 32) begin
+					lcd_display_initialization_state = 28;
+				end
+				if (lcd_display_current_character == 16) begin
+					if (lcd_display_line_two == 0) begin
+						lcd_display_line_two = 1;
+						lcd_display_initialization_state = 24;
+					end
+				end
+			end
+			33:begin
+				// End!
+				remote_access_lcd_rs_out_reg = 0;
+				remote_access_lcd_enable_out_reg = 0;
+				lcd_display_line_two = 0;
+				lcd_display_current_character = 0;
+				if (update_lcd_display == 1) begin
+					lcd_display_line_two = 0;
+					lcd_display_current_character = 0;
+					lcd_display_initialization_state = 24;
+					lcd_display_string[0] = received_lcd_display_string[0];
+					lcd_display_string[1] = received_lcd_display_string[1];
+					lcd_display_string[2] = received_lcd_display_string[2];
+					lcd_display_string[3] = received_lcd_display_string[3];
+					lcd_display_string[4] = received_lcd_display_string[4];
+					lcd_display_string[5] = received_lcd_display_string[5];
+					lcd_display_string[6] = received_lcd_display_string[6];
+					lcd_display_string[7] = received_lcd_display_string[7];
+					lcd_display_string[8] = received_lcd_display_string[8];
+					lcd_display_string[9] = received_lcd_display_string[9];
+					lcd_display_string[10] = received_lcd_display_string[10];
+					lcd_display_string[11] = received_lcd_display_string[11];
+					lcd_display_string[12] = received_lcd_display_string[12];
+					lcd_display_string[13] = received_lcd_display_string[13];
+					lcd_display_string[14] = received_lcd_display_string[14];
+					lcd_display_string[15] = received_lcd_display_string[15];
+					lcd_display_string[16] = received_lcd_display_string[16];
+					lcd_display_string[17] = received_lcd_display_string[17];
+					lcd_display_string[18] = received_lcd_display_string[18];
+					lcd_display_string[19] = received_lcd_display_string[19];
+					lcd_display_string[20] = received_lcd_display_string[20];
+					lcd_display_string[21] = received_lcd_display_string[21];
+					lcd_display_string[22] = received_lcd_display_string[22];
+					lcd_display_string[23] = received_lcd_display_string[23];
+					lcd_display_string[24] = received_lcd_display_string[24];
+					lcd_display_string[25] = received_lcd_display_string[25];
+					lcd_display_string[26] = received_lcd_display_string[26];
+					lcd_display_string[27] = received_lcd_display_string[27];
+					lcd_display_string[28] = received_lcd_display_string[28];
+					lcd_display_string[29] = received_lcd_display_string[29];
+					lcd_display_string[30] = received_lcd_display_string[30];
+					lcd_display_string[31] = received_lcd_display_string[31];
+				end
+			end
+		endcase
+	end
+endmodule
+
+module async_receiver(clk, RxD, RxD_data_ready, RxD_data, RxD_endofpacket, RxD_idle);
+	input clk, RxD;
+	output RxD_data_ready;  // onc clock pulse when RxD_data is valid
+	output [7:0] RxD_data;
+	
+	parameter ClkFrequency = 25000000;	// 25MHz
+	parameter Baud = 115200;
+	
+	// We also detect if a gap occurs in the received stream of characters
+	// That can be useful if multiple characters are sent in burst
+	//  so that multiple characters can be treated as a "packet"
+	output RxD_endofpacket;  // one clock pulse, when no more data is received (RxD_idle is going high)
+	output RxD_idle;  // no data is being received
+	
+	// Baud generator (we use 8 times oversampling)
+	parameter Baud8 = Baud*8;
+	parameter Baud8GeneratorAccWidth = 16;
+	wire [Baud8GeneratorAccWidth:0] Baud8GeneratorInc = ((Baud8<<(Baud8GeneratorAccWidth-7))+(ClkFrequency>>8))/(ClkFrequency>>7);
+	reg [Baud8GeneratorAccWidth:0] Baud8GeneratorAcc;
+	always @(posedge clk) Baud8GeneratorAcc <= Baud8GeneratorAcc[Baud8GeneratorAccWidth-1:0] + Baud8GeneratorInc;
+	wire Baud8Tick = Baud8GeneratorAcc[Baud8GeneratorAccWidth];
+	
+	////////////////////////////
+	reg [1:0] RxD_sync_inv;
+	always @(posedge clk) if(Baud8Tick) RxD_sync_inv <= {RxD_sync_inv[0], ~RxD};
+	// we invert RxD, so that the idle becomes "0", to prevent a phantom character to be received at startup
+	
+	reg [1:0] RxD_cnt_inv;
+	reg RxD_bit_inv;
+	
+	always @(posedge clk)
+	if(Baud8Tick)
+	begin
+		if( RxD_sync_inv[1] && RxD_cnt_inv!=2'b11) RxD_cnt_inv <= RxD_cnt_inv + 2'h1;
+		else 
+		if(~RxD_sync_inv[1] && RxD_cnt_inv!=2'b00) RxD_cnt_inv <= RxD_cnt_inv - 2'h1;
+	
+		if(RxD_cnt_inv==2'b00) RxD_bit_inv <= 1'b0;
+		else
+		if(RxD_cnt_inv==2'b11) RxD_bit_inv <= 1'b1;
+	end
+	
+	reg [3:0] state;
+	reg [3:0] bit_spacing;
+	
+	// "next_bit" controls when the data sampling occurs
+	// depending on how noisy the RxD is, different values might work better
+	// with a clean connection, values from 8 to 11 work
+	wire next_bit = (bit_spacing==4'd10);
+	
+	always @(posedge clk)
+	if(state==0)
+		bit_spacing <= 4'b0000;
+	else
+	if(Baud8Tick)
+		bit_spacing <= {bit_spacing[2:0] + 4'b0001} | {bit_spacing[3], 3'b000};
+	
+	always @(posedge clk)
+	if(Baud8Tick)
+	case(state)
+		4'b0000: if(RxD_bit_inv) state <= 4'b1000;  // start bit found?
+		4'b1000: if(next_bit) state <= 4'b1001;  // bit 0
+		4'b1001: if(next_bit) state <= 4'b1010;  // bit 1
+		4'b1010: if(next_bit) state <= 4'b1011;  // bit 2
+		4'b1011: if(next_bit) state <= 4'b1100;  // bit 3
+		4'b1100: if(next_bit) state <= 4'b1101;  // bit 4
+		4'b1101: if(next_bit) state <= 4'b1110;  // bit 5
+		4'b1110: if(next_bit) state <= 4'b1111;  // bit 6
+		4'b1111: if(next_bit) state <= 4'b0001;  // bit 7
+		4'b0001: if(next_bit) state <= 4'b0000;  // stop bit
+		default: state <= 4'b0000;
+	endcase
+	
+	reg [7:0] RxD_data;
+	always @(posedge clk)
+	if(Baud8Tick && next_bit && state[3]) RxD_data <= {~RxD_bit_inv, RxD_data[7:1]};
+	
+	reg RxD_data_ready;
+	always @(posedge clk)
+	begin
+		RxD_data_ready <= (Baud8Tick && next_bit && state==4'b0001 && ~RxD_bit_inv);  // ready only if the stop bit is received
+	end
+	
+	reg [4:0] gap_count;
+	always @(posedge clk) if (state!=0) gap_count<=5'h00; else if(Baud8Tick & ~gap_count[4]) gap_count <= gap_count + 5'h01;
+	assign RxD_idle = gap_count[4];
+	reg RxD_endofpacket; always @(posedge clk) RxD_endofpacket <= Baud8Tick & (gap_count==5'h0F);
+endmodule
+
+module async_transmit(clk, TxD_start, TxD_data, TxD, TxD_busy, state);
+	input clk, TxD_start;
+	input [7:0] TxD_data;
+	output TxD, TxD_busy;
+	output [4:0] state;
+	parameter ClkFrequency = 25000000;	// 25MHz
+	//parameter ClkFrequency = 50000000;	// 50MHz
+	parameter Baud = 115200;
+	parameter RegisterInputData = 1;	// in RegisterInputData mode, the input doesn't have to stay valid while the character is been transmitted
+	
+	// Baud generator
+	parameter BaudGeneratorAccWidth = 16;
+	reg [BaudGeneratorAccWidth:0] BaudGeneratorAcc;
+	`ifdef DEBUG
+	wire [BaudGeneratorAccWidth:0] BaudGeneratorInc = 17'h10000;
+	`else
+	wire [BaudGeneratorAccWidth:0] BaudGeneratorInc = ((Baud<<(BaudGeneratorAccWidth-4))+(ClkFrequency>>5))/(ClkFrequency>>4);
+	`endif
+	
+	wire BaudTick = BaudGeneratorAcc[BaudGeneratorAccWidth];
+	wire TxD_busy;
+	always @(posedge clk) if(TxD_busy) BaudGeneratorAcc <= BaudGeneratorAcc[BaudGeneratorAccWidth-1:0] + BaudGeneratorInc;
+	
+	// Transmitter state machine
+	reg [4:0] state;
+	wire TxD_ready = (state==0);
+	assign TxD_busy = ~TxD_ready;
+	
+	reg [7:0] TxD_dataReg;
+	always @(posedge clk) if(TxD_ready & TxD_start) TxD_dataReg <= TxD_data;
+	wire [7:0] TxD_dataD = RegisterInputData ? TxD_dataReg : TxD_data;
+	
+	always @(posedge clk) begin
+		if (TxD_start == 0) state <= 5'b00000;
+	
+		case(state)
+			5'b00000: if(TxD_start) state <= 5'b00001;
+			5'b00001: if(BaudTick) state <= 5'b00100;
+			5'b00100: if(BaudTick) state <= 5'b01000;  // start
+			5'b01000: if(BaudTick) state <= 5'b01001;  // bit 0
+			5'b01001: if(BaudTick) state <= 5'b01010;  // bit 1
+			5'b01010: if(BaudTick) state <= 5'b01011;  // bit 2
+			5'b01011: if(BaudTick) state <= 5'b01100;  // bit 3
+			5'b01100: if(BaudTick) state <= 5'b01101;  // bit 4
+			5'b01101: if(BaudTick) state <= 5'b01110;  // bit 5
+			5'b01110: if(BaudTick) state <= 5'b01111;  // bit 6
+			5'b01111: if(BaudTick) state <= 5'b00010;  // bit 7
+			5'b00010: if(BaudTick) state <= 5'b00011;  // stop1
+			//4'b0011: if(BaudTick) state <= 4'b0000;  // stop2
+			5'b00011: if(BaudTick) state <= 5'b10000;  // stop2
+			//default: if(BaudTick) state <= 4'b0000;
+		endcase
+	end
+	
+	// Output mux
+	reg muxbit;
+	always @( * )
+	case(state[2:0])
+		3'd0: muxbit <= TxD_dataD[0];
+		3'd1: muxbit <= TxD_dataD[1];
+		3'd2: muxbit <= TxD_dataD[2];
+		3'd3: muxbit <= TxD_dataD[3];
+		3'd4: muxbit <= TxD_dataD[4];
+		3'd5: muxbit <= TxD_dataD[5];
+		3'd6: muxbit <= TxD_dataD[6];
+		3'd7: muxbit <= TxD_dataD[7];
+	endcase
+	
+	// Put together the start, data and stop bits
+	reg TxD;
+	always @(posedge clk) TxD <= (state<4) | (state[3] & muxbit) | state[4];  // register the output to make it glitch free
+
+endmodule
diff --git a/fpga/xilinx/digilent/spartan_3e/remote_access.v b/fpga/xilinx/digilent/spartan_3e/remote_access.v
new file mode 100644
index 0000000..154478e
--- /dev/null
+++ b/fpga/xilinx/digilent/spartan_3e/remote_access.v
@@ -0,0 +1,1184 @@
+`timescale 1ns / 1ps
+//////////////////////////////////////////////////////////////////////////////////
+// Company: 			Pearson Computing
+// Engineer: 			Timothy Pearson
+// 
+// Create Date:    	11:58:21 07/07/2007 
+// Design Name:		Remote Access Driver
+// Module Name:    	remote_access 
+// Project Name: 		Remote Access Driver
+// Target Devices: 	Digilent Spartan 3E Development Board
+// Tool versions: 	Xilinx ISE v9.1 SP3
+// Description: 		Serial remote access driver and LCD display driver
+//
+// Dependencies: 
+//
+// Revision: 
+// Revision 0.01 - File Created
+// Additional Comments: Released into the Public Domain
+//
+//////////////////////////////////////////////////////////////////////////////////
+module remote_access(
+	input main_fifty_clock,								// 50MHz clock in
+	input [3:0] remote_access_4_bit_output,		// 4 bit output from the user program to remote access client
+	output [3:0] remote_access_4_bit_input,		// 4 bit input from the remote access client to user program
+	input [7:0] remote_access_8_bit_output,		// 8 bit output from the user program to remote access client
+	output [7:0] remote_access_8_bit_input,		// 8 bit input from the remote access client to user program
+	input [15:0] remote_access_16_bit_output,	// 16 bit output from the user program to the remote access client
+	output [15:0] remote_access_16_bit_input,	// 16 bit input from the remote access client to the user program 
+	output [3:0] remote_access_lcd_data_out,
+	output remote_access_lcd_rs_out,
+	output remote_access_lcd_rw_out,
+	output remote_access_lcd_enable_out,
+	input serial_port_receiver,
+	output serial_port_transmitter,
+	input remote_access_input_enable,
+	input [7:0] local_input,
+	input seize_serial_tx,
+	input [7:0] serial_tx_data,
+	input serial_tx_strobe,
+	output [7:0] serial_rx_data,
+	output serial_rx_strobe,
+	input [5:0] lcd_data_in_address,
+	input [7:0] lcd_data_in_data,
+	input lcd_data_in_enable,
+	input sram_wren_in,
+	input sram_clock_in,
+	input [7:0] sram_data_in,
+	input [13:0] sram_address_in,
+	output [7:0] sram_data_out,
+	output sram_available,
+	input sram_processing_done,
+	input [7:0] led_segment_bus,
+	input [3:0] led_digit_select);
+	
+	reg [7:0] remote_access_4_bit_input_reg;
+	reg [7:0] remote_access_8_bit_input_reg;
+	reg [15:0] remote_access_16_bit_input_reg;
+	reg [3:0] remote_access_lcd_data_out_reg;
+	reg remote_access_lcd_rs_out_reg;
+	reg remote_access_lcd_rw_out_reg;
+	reg remote_access_lcd_enable_out_reg;
+	reg [7:0] serial_rx_data_reg;
+	reg serial_rx_strobe_reg;
+	reg sram_available_reg;
+	reg startup_needed = 1;
+	
+	assign remote_access_4_bit_input = remote_access_4_bit_input_reg;
+	assign remote_access_8_bit_input = remote_access_8_bit_input_reg;
+	assign remote_access_16_bit_input = remote_access_16_bit_input_reg;
+	assign remote_access_lcd_data_out = remote_access_lcd_data_out_reg;
+	assign remote_access_lcd_rs_out = remote_access_lcd_rs_out_reg;
+	assign remote_access_lcd_rw_out = remote_access_lcd_rw_out_reg;
+	assign remote_access_lcd_enable_out = remote_access_lcd_enable_out_reg;
+	assign serial_rx_data = serial_rx_data_reg;
+	assign serial_rx_strobe = serial_rx_strobe_reg;
+	assign sram_available = sram_available_reg;
+	
+	//-----------------------------------------------------------------------------------
+	//
+	// Create a 4.16MHz clock for the LCD display driver and a 25MHz clock 
+	// for the serial receiver.
+	//
+	//-----------------------------------------------------------------------------------
+	
+	reg four_mhz_clk;
+	reg clk_div_by_two;
+	reg clk_div_by_four;
+	reg clk_div_by_eight;
+	reg [3:0] fifty_clock_divider = 0;
+	
+	always @(posedge main_fifty_clock) begin
+		fifty_clock_divider = fifty_clock_divider + 1;
+		if (fifty_clock_divider > 12) begin
+			four_mhz_clk = !four_mhz_clk;
+			fifty_clock_divider = 0;
+		end
+	end
+	
+	always @(posedge main_fifty_clock) begin
+		clk_div_by_two = !clk_div_by_two;
+	end
+	
+	always @(posedge clk_div_by_two) begin
+		clk_div_by_four = !clk_div_by_four;
+	end
+	
+	always @(posedge clk_div_by_four) begin
+		clk_div_by_eight = !clk_div_by_eight;
+	end
+	
+	//-----------------------------------------------------------------------------------
+	//
+	// Keep track of what is on the LED display
+	//
+	//-----------------------------------------------------------------------------------
+	
+	reg [7:0] led_display_bytes [3:0];
+	reg [4:0] digit_blanker_1 = 0;
+	reg [4:0] digit_blanker_2 = 0;
+	reg [4:0] digit_blanker_3 = 0;
+	reg [4:0] digit_blanker_4 = 0;
+	
+	always @(negedge clk_div_by_eight) begin
+		if (led_digit_select[0] == 0) begin
+			led_display_bytes[0] = led_segment_bus;
+			digit_blanker_1 = 0;
+		end
+		
+		if (led_digit_select[1] == 0) begin
+			led_display_bytes[1] = led_segment_bus;
+			digit_blanker_2 = 0;
+		end
+		
+		if (led_digit_select[2] == 0) begin
+			led_display_bytes[2] = led_segment_bus;
+			digit_blanker_3 = 0;
+		end
+		
+		if (led_digit_select[3] == 0) begin
+			led_display_bytes[3] = led_segment_bus;
+			digit_blanker_4 = 0;
+		end
+		
+		if (digit_blanker_1 > 30) begin
+			led_display_bytes[0] = 255;
+		end
+		
+		if (digit_blanker_2 > 30) begin
+			led_display_bytes[1] = 255;
+		end
+		
+		if (digit_blanker_3 > 30) begin
+			led_display_bytes[2] = 255;
+		end
+		
+		if (digit_blanker_4 > 30) begin
+			led_display_bytes[3] = 255;
+		end
+	end
+	
+	//-----------------------------------------------------------------------------------
+	//
+	// Instantiate the data storage RAM for signal processing
+	//
+	//-----------------------------------------------------------------------------------
+
+	reg data_storage_remote_enable = 0;
+	wire data_storage_clka;
+	wire [7:0] data_storage_dina;
+	wire [13:0] data_storage_addra;
+	wire data_storage_write_enable;
+	wire [7:0] data_storage_data_out;
+	
+	reg [7:0] data_storage_dina_reg;
+	reg [13:0] data_storage_addra_reg;
+	reg data_storage_write_enable_reg;
+
+	data_storage data_storage(.clka(data_storage_clka), .dina(data_storage_dina), .addra(data_storage_addra), 
+		.wea(data_storage_write_enable), .douta(data_storage_data_out));
+	
+	assign data_storage_clka = (data_storage_remote_enable) ? main_fifty_clock : sram_clock_in;
+	assign data_storage_dina = (data_storage_remote_enable) ? data_storage_dina_reg : sram_data_in;
+	assign data_storage_addra = (data_storage_remote_enable) ? data_storage_addra_reg : sram_address_in;
+	assign data_storage_write_enable = (data_storage_remote_enable) ? data_storage_write_enable_reg : sram_wren_in;
+	
+	assign sram_data_out = data_storage_data_out;
+	
+	// -----------------------------------------------------------------------------------------------
+	//
+	// Here is the serial receiver and transmitter
+	//
+	// -----------------------------------------------------------------------------------------------
+
+	reg [7:0] transmit_all_data_state = 0;
+
+	wire RxD_data_ready;
+	wire [7:0] RxD_data;
+	wire RxD_endofpacket;
+	wire RxD_idle;
+
+	reg TxD_start;
+	reg [7:0] TxD_data;
+	wire TxD_busy;
+	wire [4:0] state;
+	
+	reg [7:0] transmitter_4_bit_state = 0;
+	reg [7:0] transmitter_8_bit_state = 0;
+	reg [15:0] transmitter_16_bit_state = 0;
+	reg [7:0] transmitter_main_state = 0;
+	reg [7:0] transmitter_input_state = 0;
+
+	async_transmit asyncTX(.clk(clk_div_by_two), .TxD_start(TxD_start), .TxD_data(TxD_data), .TxD(serial_port_transmitter), .TxD_busy(TxD_busy), .state(state));
+	async_receiver asyncRX(.clk(clk_div_by_two), .RxD(serial_port_receiver), .RxD_data_ready(RxD_data_ready), .RxD_data(RxD_data), .RxD_endofpacket(RxD_endofpacket), .RxD_idle(RxD_idle));
+
+	reg tx_toggle = 0;
+	
+	reg transmit_4_bit_status = 0;
+	reg transmit_4_bit_status_done = 0;
+	
+	reg transmit_8_bit_status = 0;
+	reg transmit_8_bit_status_done = 0;
+	
+	reg transmit_16_bit_status = 0;
+	reg transmit_16_bit_pass_two = 0;
+	reg transmit_16_bit_status_done = 0;
+	
+	reg transmit_main_status = 0;
+	reg transmit_main_status_done = 0;
+	
+	reg transmit_input_status = 0;
+	reg transmit_input_status_done = 0;
+	
+	reg transmit_lcd_status = 0;
+	reg transmit_lcd_status_done = 0;
+	reg [7:0] transmit_lcd_status_counter = 0;
+	
+	reg enable_remote_access_input = 1;
+	reg remote_access_input_enable_prev = 0;
+	reg prev_was_carriage_return = 0;
+	
+	reg [7:0] lcd_display_string [31:0];
+	
+	reg transmit_dsp_status = 0;
+	reg transmit_dsp_status_done = 0;
+	reg transmit_dsp_status_holdoff = 0;
+	reg [15:0] transmit_dsp_status_counter = 0;
+	
+	reg transmit_led_status = 0;
+	reg transmit_led_status_done = 0;
+	reg [7:0] transmit_led_status_counter = 0;
+	
+	// Transmit!	
+	always @(posedge clk_div_by_two) begin
+		transmitter_4_bit_state = remote_access_4_bit_output;
+		transmitter_8_bit_state = remote_access_8_bit_output;
+		transmitter_16_bit_state = remote_access_16_bit_output;
+		
+		transmitter_main_state = 0;
+		transmitter_main_state[0] = enable_remote_access_input;
+		
+		transmitter_input_state = local_input;
+	
+		if (seize_serial_tx == 1) begin
+			TxD_start = serial_tx_strobe;
+			TxD_data = serial_tx_data;
+		end else begin
+			if (tx_toggle == 0) begin
+				if ((transmit_4_bit_status == 1) && (transmit_4_bit_status_done == 0)) begin
+					TxD_data = transmitter_4_bit_state;
+												
+					TxD_start = 1;
+					tx_toggle = 1;
+					
+					transmit_4_bit_status_done = 1;
+				end
+				
+				if ((transmit_8_bit_status == 1) && (transmit_8_bit_status_done == 0)) begin
+					TxD_data = transmitter_8_bit_state;
+												
+					TxD_start = 1;
+					tx_toggle = 1;
+					
+					transmit_8_bit_status_done = 1;
+				end
+				
+				if ((transmit_16_bit_status == 1) && (transmit_16_bit_status_done == 0)) begin
+					if (transmit_16_bit_pass_two == 0) begin
+						TxD_data = transmitter_16_bit_state[15:8];
+						
+						TxD_start = 1;
+						tx_toggle = 1;	
+						
+						transmit_16_bit_pass_two = 1;
+					end else begin
+						TxD_data = transmitter_16_bit_state[7:0];
+						
+						TxD_start = 1;
+						tx_toggle = 1;	
+						
+						transmit_16_bit_status_done = 1;
+					end
+				end
+				
+				if ((transmit_main_status == 1) && (transmit_main_status_done == 0)) begin
+					TxD_data = transmitter_main_state;
+												
+					TxD_start = 1;
+					tx_toggle = 1;
+					
+					transmit_main_status_done = 1;
+				end
+				
+				if ((transmit_input_status == 1) && (transmit_input_status_done == 0)) begin
+					TxD_data = transmitter_input_state;
+												
+					TxD_start = 1;
+					tx_toggle = 1;
+					
+					transmit_input_status_done = 1;
+				end
+				
+				if ((transmit_lcd_status == 1) && (transmit_lcd_status_done == 0)) begin
+					TxD_data = lcd_display_string[transmit_lcd_status_counter];
+												
+					TxD_start = 1;
+					tx_toggle = 1;
+					
+					transmit_lcd_status_counter = transmit_lcd_status_counter + 1;
+					if (transmit_lcd_status_counter > 31) begin
+						transmit_lcd_status_done = 1;
+					end
+				end
+				
+				if ((transmit_led_status == 1) && (transmit_led_status_done == 0)) begin
+					TxD_data = led_display_bytes[transmit_led_status_counter];
+												
+					TxD_start = 1;
+					tx_toggle = 1;
+					
+					transmit_led_status_counter = transmit_led_status_counter + 1;
+					if (transmit_led_status_counter > 3) begin
+						transmit_led_status_done = 1;
+					end
+				end
+				
+				if ((transmit_dsp_status == 1) && (transmit_dsp_status_done == 0)) begin
+					if (transmit_dsp_status_holdoff == 0) begin
+						transmit_dsp_status_holdoff = 1;
+						data_storage_write_enable_reg = 0;
+						data_storage_addra_reg = 0;			// Initial data value
+					end else begin
+						data_storage_write_enable_reg = 0;
+						TxD_data = data_storage_data_out;
+													
+						TxD_start = 1;
+						tx_toggle = 1;
+						
+						transmit_dsp_status_counter = transmit_dsp_status_counter + 1;
+						data_storage_addra_reg = transmit_dsp_status_counter;
+						if (transmit_dsp_status_counter > 16384) begin
+							transmit_dsp_status_done = 1;
+							data_storage_write_enable_reg = 1'bz;
+							data_storage_addra_reg = 14'bz;
+						end
+					end
+				end
+			end else begin
+				if (state == 5'b10000) begin	// Wait for transmission of byte to complete
+					TxD_start = 0;
+					tx_toggle = 0;
+				end
+			end
+		end
+		
+		if (transmit_4_bit_status == 0) begin
+			transmit_4_bit_status_done = 0;
+		end
+		
+		if (transmit_8_bit_status == 0) begin
+			transmit_8_bit_status_done = 0;
+		end
+		
+		if (transmit_16_bit_status == 0) begin
+			transmit_16_bit_pass_two = 0;
+			transmit_16_bit_status_done = 0;
+		end
+		
+		if (transmit_main_status == 0) begin
+			transmit_main_status_done = 0;
+		end
+		
+		if (transmit_input_status == 0) begin
+			transmit_input_status_done = 0;
+		end
+		
+		if (transmit_lcd_status == 0) begin
+			transmit_lcd_status_done = 0;
+			transmit_lcd_status_counter = 0;
+		end
+		
+		if (transmit_led_status == 0) begin
+			transmit_led_status_done = 0;
+			transmit_led_status_counter = 0;
+		end
+		
+		if (transmit_dsp_status == 0) begin
+			transmit_dsp_status_done = 0;
+			transmit_dsp_status_holdoff = 0;
+			transmit_dsp_status_counter = 0;
+		end
+	end
+
+	reg [7:0] lcd_display_initialization_state = 0;
+	reg serial_character_received = 0;
+	reg [7:0] serial_receiver_toggler = 0;
+	reg [7:0] serial_command_buffer = 0;
+	reg [2:0] next_byte_is_command = 0;
+	reg [7:0] next_byte_is_command_prev_command = 0;
+	reg [7:0] serial_command_timer = 0;
+	reg update_lcd_display = 0;
+	reg [7:0] serial_update_counter = 0;
+	reg [15:0] dsp_update_counter = 0;
+	reg [7:0] received_lcd_display_string [31:0];
+	reg data_write_timer = 0;
+	reg waiting_on_dsp_processing = 0;
+	
+	// Receive serial commands
+	always @(posedge clk_div_by_two) begin
+		if (startup_needed == 1) begin
+			startup_needed = 0;
+			transmit_dsp_status = 1;
+		end
+	
+		if (lcd_data_in_enable == 1) begin
+			received_lcd_display_string[lcd_data_in_address] = lcd_data_in_data;
+			update_lcd_display = 1;
+			serial_command_timer = 255;
+		end
+	
+		if ((remote_access_input_enable == 1) && (remote_access_input_enable_prev == 0)) begin
+			enable_remote_access_input = !enable_remote_access_input;
+		end
+		remote_access_input_enable_prev = remote_access_input_enable;
+	
+		if (enable_remote_access_input == 0) begin
+			// Enable local input
+			remote_access_8_bit_input_reg = local_input;
+		end
+	
+		if (serial_command_timer > 0) begin
+			serial_command_timer = serial_command_timer - 1;
+		end else begin
+			update_lcd_display = 0;
+		end
+		
+		if (transmit_4_bit_status_done == 1) begin
+			transmit_4_bit_status = 0;
+			if (transmit_all_data_state == 1) begin
+				transmit_8_bit_status = 1;
+			end
+		end
+		
+		if (transmit_8_bit_status_done == 1) begin
+			transmit_8_bit_status = 0;
+			if (transmit_all_data_state == 1) begin
+				transmit_16_bit_status = 1;
+			end
+		end
+		
+		if (transmit_16_bit_status_done == 1) begin
+			transmit_16_bit_status = 0;
+			if (transmit_all_data_state == 1) begin
+				transmit_led_status = 1;
+			end
+		end
+		
+		if (transmit_led_status_done == 1) begin
+			transmit_led_status = 0;
+			if (transmit_all_data_state == 1) begin
+				transmit_all_data_state = 0;
+			end
+		end
+		
+		if (transmit_main_status_done == 1) begin
+			transmit_main_status = 0;
+			if (transmit_all_data_state == 1) begin
+				transmit_4_bit_status = 1;
+			end
+		end
+		
+		if (transmit_input_status_done == 1) begin
+			transmit_input_status = 0;
+		end
+		
+		if (transmit_lcd_status_done == 1) begin
+			transmit_lcd_status = 0;
+			if (transmit_all_data_state == 1) begin
+				transmit_main_status = 1;
+			end
+		end
+		
+		if (transmit_dsp_status_done == 1) begin
+			transmit_dsp_status = 0;
+			data_storage_remote_enable = 0;
+		end
+		
+		if (transmit_dsp_status == 1) begin
+			data_storage_remote_enable = 1;
+		end
+		
+		if (data_write_timer > 1) begin
+			data_write_timer = data_write_timer - 1;
+		end else begin
+			if (data_write_timer == 1) begin
+				data_storage_write_enable_reg = 0;
+				data_write_timer = 0;
+			end
+		end
+		
+		if ((waiting_on_dsp_processing == 1) && (sram_processing_done == 1)) begin
+			waiting_on_dsp_processing = 0;
+			transmit_dsp_status = 1;
+		end
+	
+		serial_rx_strobe_reg = 0;		// Make sure that this get reset!
+		
+		if ((sram_processing_done == 1) && (sram_available_reg == 1)) begin
+			sram_available_reg = 0;
+			transmit_dsp_status = 1;
+		end
+	
+		if (RxD_data_ready == 1) begin		
+			if (serial_character_received == 0) begin
+				serial_rx_data_reg = RxD_data;
+				serial_rx_strobe_reg = 1;		// Signal new data...
+				if (seize_serial_tx == 0) begin
+					// Parse the command and see what it is
+					serial_character_received = 1;
+					if (RxD_data == 13) begin
+						// Carriage Return!  The serial_command_buffer holds the command!  Parse it!
+						if (next_byte_is_command == 0) begin
+							if (serial_command_buffer == 65) begin
+								// Display update requested
+								next_byte_is_command = 1;
+								serial_update_counter = 0;
+								next_byte_is_command_prev_command = 65;
+							end
+							
+							if (serial_command_buffer == 66) begin
+								// 8 bit input update
+								if (enable_remote_access_input == 1) begin
+									next_byte_is_command = 1;
+									serial_update_counter = 0;
+									next_byte_is_command_prev_command = 66;
+								end
+							end
+							
+							if (serial_command_buffer == 67) begin
+								// 16 bit input update
+								next_byte_is_command = 1;
+								serial_update_counter = 0;
+								next_byte_is_command_prev_command = 67;
+							end
+							
+							if (serial_command_buffer == 68) begin
+								// 8 bit output status
+								transmit_8_bit_status = 1;
+							end
+							
+							if (serial_command_buffer == 69) begin
+								// 16 bit output status
+								transmit_16_bit_status = 1;
+							end
+							
+							if (serial_command_buffer == 70) begin
+								// System status
+								transmit_main_status = 1;
+							end
+							
+							if (serial_command_buffer == 71) begin
+								// Simulate center button press
+								enable_remote_access_input = !enable_remote_access_input;
+							end
+							
+							if (serial_command_buffer == 72) begin
+								// Local input status
+								transmit_input_status = 1;
+							end
+							
+							if (serial_command_buffer == 73) begin
+								// 4 bit input update
+								if (enable_remote_access_input == 1) begin
+									next_byte_is_command = 1;
+									serial_update_counter = 0;
+									next_byte_is_command_prev_command = 73;
+								end
+							end
+							
+							if (serial_command_buffer == 74) begin
+								// 4 bit output status
+								transmit_4_bit_status = 1;
+							end
+							
+							if (serial_command_buffer == 75) begin
+								// Transmit the contents of the LCD...
+								transmit_lcd_status = 1;
+							end
+							
+							if (serial_command_buffer == 76) begin
+								// Transmit the contents of the LCD...
+								transmit_all_data_state = 1;
+								transmit_lcd_status = 1;
+							end
+							
+							if (serial_command_buffer == 77) begin
+								// Receive offline DSP data
+								next_byte_is_command = 1;
+								dsp_update_counter = 0;
+								next_byte_is_command_prev_command = 77;
+							end
+							
+							if (serial_command_buffer == 78) begin
+								// Transmit the contents of RAM...
+								transmit_dsp_status = 1;
+							end
+						end else begin														
+							if (next_byte_is_command == 1) begin
+								// The previous byte was the command--now load in the data!
+								if (next_byte_is_command_prev_command == 65) begin
+									if (serial_update_counter < 32) begin
+										received_lcd_display_string[serial_update_counter] = serial_command_buffer;
+										serial_update_counter = serial_update_counter + 1;
+									end else begin
+										update_lcd_display = 1;
+										serial_command_timer = 255;
+										next_byte_is_command = 0;
+									end
+								end
+								
+								// 4 bit input update
+								if (next_byte_is_command_prev_command == 73) begin
+									remote_access_4_bit_input_reg = serial_command_buffer;
+									next_byte_is_command = 0;
+								end
+								
+								// 8 bit input update
+								if (next_byte_is_command_prev_command == 66) begin
+									remote_access_8_bit_input_reg = serial_command_buffer;
+									next_byte_is_command = 0;
+								end
+								
+								// 16 bit input update
+								if (next_byte_is_command_prev_command == 67) begin
+									if (serial_update_counter == 0) begin
+										remote_access_16_bit_input_reg[15:8] = serial_command_buffer;
+										serial_update_counter = 1;
+									end else begin
+										remote_access_16_bit_input_reg[7:0] = serial_command_buffer;
+										next_byte_is_command = 0;
+									end
+								end
+								
+								// DSP input data
+								if (next_byte_is_command_prev_command == 77) begin
+									if (dsp_update_counter < 16384) begin
+										data_storage_remote_enable = 1;
+										data_storage_addra_reg = dsp_update_counter;
+										data_storage_dina_reg = serial_command_buffer;
+										data_storage_write_enable_reg = 1;
+										data_write_timer = 3;
+										dsp_update_counter = dsp_update_counter + 1;
+										
+										// TESTING ONLY!!!
+										//if (dsp_update_counter < 17) begin
+										//	received_lcd_display_string[dsp_update_counter - 1] = serial_command_buffer;
+										//end
+									end else begin
+										next_byte_is_command = 0;
+										data_storage_write_enable_reg = 0;
+										data_storage_remote_enable = 0;
+										sram_available_reg = 1;
+										data_storage_write_enable_reg = 1'bz;
+										data_storage_addra_reg = 14'bz;
+										waiting_on_dsp_processing = 1;
+										
+										// TESTING ONLY!!!
+										//transmit_dsp_status = 1;
+									end
+								end
+							end
+						end
+					end
+				end
+				
+				//if (RxD_data != 10) begin		// Ignore linefeeds
+					serial_command_buffer = RxD_data;
+				//end
+				
+				if (RxD_data == 13) begin
+					prev_was_carriage_return = 1;
+				end else begin
+					prev_was_carriage_return = 0;
+				end
+			
+				serial_receiver_toggler = serial_receiver_toggler + 1;
+			end
+		end
+		
+		if (RxD_data_ready == 0) begin
+			serial_character_received = 0;
+		end
+	end
+	
+	//-----------------------------------------------------------------------------------
+	//
+	// This routine will display the contents of lcd_display_string on the LCD display
+	//
+	//-----------------------------------------------------------------------------------
+	
+	reg [15:0] lcd_display_wait_counter = 0;
+	reg [7:0] lcd_display_current_character = 0;
+	reg lcd_display_line_two = 0;		// Are we trying to write to line two?
+	
+	always @(posedge four_mhz_clk) begin	
+		case (lcd_display_initialization_state)
+			// Initialize the display according to the reference manual
+			0:begin
+				// Set up the default display...
+				lcd_display_string[0] = 73;		// I
+				lcd_display_string[1] = 110;		// n
+				lcd_display_string[2] = 105;		// i
+				lcd_display_string[3] = 116;		// t
+				lcd_display_string[4] = 105;		// i
+				lcd_display_string[5] = 97;		// a
+				lcd_display_string[6] = 108;		// l
+				lcd_display_string[7] = 105;		// i
+				lcd_display_string[8] = 122;		// z
+				lcd_display_string[9] = 97;		// a
+				lcd_display_string[10] = 116;	// t
+				lcd_display_string[11] = 105;	// i
+				lcd_display_string[12] = 111;	// o
+				lcd_display_string[13] = 110;	// n
+				lcd_display_string[14] = 32;		// <blank>
+				lcd_display_string[15] = 32;		// <blank>
+				lcd_display_string[16] = 79;		// O
+				lcd_display_string[17] = 75;		// k
+				lcd_display_string[18] = 32;		// <blank>
+				lcd_display_string[19] = 32;		// <blank>
+				lcd_display_string[20] = 32;		// <blank>
+				lcd_display_string[21] = 32;		// <blank>
+				lcd_display_string[22] = 32;		// <blank>
+				lcd_display_string[23] = 32;		// <blank>
+				lcd_display_string[24] = 32;		// <blank>
+				lcd_display_string[25] = 32;		// <blank>
+				lcd_display_string[26] = 32;		// <blank>
+				lcd_display_string[27] = 32;		// <blank>
+				lcd_display_string[28] = 32;		// <blank>
+				lcd_display_string[29] = 32;		// <blank>
+				lcd_display_string[30] = 32;		// <blank>
+				lcd_display_string[31] = 32;		// <blank>
+			
+				lcd_display_current_character = 0;
+				
+				lcd_display_line_two = 0;
+				remote_access_lcd_data_out_reg = 3;
+				remote_access_lcd_enable_out_reg = 1;
+				remote_access_lcd_rs_out_reg = 0;
+				remote_access_lcd_rw_out_reg = 0;
+				lcd_display_wait_counter = 17083;	// Wait 15mS
+				lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			1:begin
+				remote_access_lcd_enable_out_reg = 0;
+				lcd_display_wait_counter = lcd_display_wait_counter - 1;
+				if (lcd_display_wait_counter == 0) lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			2:begin
+				remote_access_lcd_data_out_reg = 3;
+				remote_access_lcd_enable_out_reg = 1;
+				lcd_display_wait_counter = 417;		// Wait 100uS
+				lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			3:begin
+				remote_access_lcd_enable_out_reg = 0;
+				lcd_display_wait_counter = lcd_display_wait_counter - 1;
+				if (lcd_display_wait_counter == 0) lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			4:begin
+				remote_access_lcd_data_out_reg = 3;
+				remote_access_lcd_enable_out_reg = 1;
+				lcd_display_wait_counter = 167;		// Wait 40uS
+				lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			5:begin
+				remote_access_lcd_enable_out_reg = 0;
+				lcd_display_wait_counter = lcd_display_wait_counter - 1;
+				if (lcd_display_wait_counter == 0) lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			6:begin
+				remote_access_lcd_data_out_reg = 2;
+				remote_access_lcd_enable_out_reg = 1;
+				lcd_display_wait_counter = 167;		// Wait 40uS
+				lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			7:begin
+				remote_access_lcd_enable_out_reg = 0;
+				lcd_display_wait_counter = lcd_display_wait_counter - 1;
+				if (lcd_display_wait_counter == 0) lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			// Display is now initialized
+			
+			// Send Function Set command
+			8:begin
+				remote_access_lcd_data_out_reg = 2;
+				remote_access_lcd_enable_out_reg = 1;
+				lcd_display_wait_counter = 5;		// Wait 1uS
+				lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			9:begin
+				remote_access_lcd_enable_out_reg = 0;
+				lcd_display_wait_counter = lcd_display_wait_counter - 1;
+				if (lcd_display_wait_counter == 0) lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			10:begin
+				remote_access_lcd_data_out_reg = 8;
+				remote_access_lcd_enable_out_reg = 1;
+				lcd_display_wait_counter = 167;		// Wait 40uS
+				lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			11:begin
+				remote_access_lcd_enable_out_reg = 0;
+				lcd_display_wait_counter = lcd_display_wait_counter - 1;
+				if (lcd_display_wait_counter == 0) lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			
+			// Send Entry Mode Set command
+			12:begin
+				remote_access_lcd_data_out_reg = 0;
+				remote_access_lcd_enable_out_reg = 1;
+				lcd_display_wait_counter = 5;		// Wait 1uS
+				lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			13:begin
+				remote_access_lcd_enable_out_reg = 0;
+				lcd_display_wait_counter = lcd_display_wait_counter - 1;
+				if (lcd_display_wait_counter == 0) lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			14:begin
+				remote_access_lcd_data_out_reg = 6;
+				remote_access_lcd_enable_out_reg = 1;
+				lcd_display_wait_counter = 167;		// Wait 40uS
+				lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			15:begin
+				remote_access_lcd_enable_out_reg = 0;
+				lcd_display_wait_counter = lcd_display_wait_counter - 1;
+				if (lcd_display_wait_counter == 0) lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			
+			// Send Display On command and disable cursors and blinking
+			16:begin
+				remote_access_lcd_data_out_reg = 0;
+				remote_access_lcd_enable_out_reg = 1;
+				lcd_display_wait_counter = 5;		// Wait 1uS
+				lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			17:begin
+				remote_access_lcd_enable_out_reg = 0;
+				lcd_display_wait_counter = lcd_display_wait_counter - 1;
+				if (lcd_display_wait_counter == 0) lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			18:begin
+				remote_access_lcd_data_out_reg = 12;
+				remote_access_lcd_enable_out_reg = 1;
+				lcd_display_wait_counter = 167;		// Wait 40uS
+				lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			19:begin
+				remote_access_lcd_enable_out_reg = 0;
+				lcd_display_wait_counter = lcd_display_wait_counter - 1;
+				if (lcd_display_wait_counter == 0) lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			
+			// Send Clear Display command
+			20:begin
+				remote_access_lcd_data_out_reg = 0;
+				remote_access_lcd_enable_out_reg = 1;
+				lcd_display_wait_counter = 5;		// Wait 1uS
+				lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			21:begin
+				remote_access_lcd_enable_out_reg = 0;
+				lcd_display_wait_counter = lcd_display_wait_counter - 1;
+				if (lcd_display_wait_counter == 0) lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			22:begin
+				remote_access_lcd_data_out_reg = 1;
+				remote_access_lcd_enable_out_reg = 1;
+				lcd_display_wait_counter = 6833;		// Wait 1.64uS
+				lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			23:begin
+				remote_access_lcd_enable_out_reg = 0;
+				lcd_display_wait_counter = lcd_display_wait_counter - 1;
+				if (lcd_display_wait_counter == 0) lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			
+			// Set DD RAM Address to 0 if lcd_display_line_two is 0, or 0x40 if it is 1
+			24:begin
+				remote_access_lcd_rs_out_reg = 0;
+				if (lcd_display_line_two == 0) begin
+					remote_access_lcd_data_out_reg = 8;
+				end
+				if (lcd_display_line_two == 1) begin
+					remote_access_lcd_data_out_reg = 12;
+				end
+				remote_access_lcd_enable_out_reg = 1;
+				lcd_display_wait_counter = 5;		// Wait 1uS
+				lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			25:begin
+				remote_access_lcd_enable_out_reg = 0;
+				lcd_display_wait_counter = lcd_display_wait_counter - 1;
+				if (lcd_display_wait_counter == 0) lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			26:begin
+				remote_access_lcd_data_out_reg = 0;
+				remote_access_lcd_enable_out_reg = 1;
+				lcd_display_wait_counter = 167;		// Wait 40uS
+				lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			27:begin
+				remote_access_lcd_enable_out_reg = 0;
+				lcd_display_wait_counter = lcd_display_wait_counter - 1;
+				if (lcd_display_wait_counter == 0) lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			
+			// Display the characters
+			28:begin
+				remote_access_lcd_data_out_reg = lcd_display_string[lcd_display_current_character][7:4];
+				remote_access_lcd_rs_out_reg = 1;
+				remote_access_lcd_enable_out_reg = 1;
+				lcd_display_wait_counter = 5;		// Wait 1uS
+				lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			29:begin
+				remote_access_lcd_enable_out_reg = 0;
+				lcd_display_wait_counter = lcd_display_wait_counter - 1;
+				if (lcd_display_wait_counter == 0) lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			30:begin
+				remote_access_lcd_data_out_reg = lcd_display_string[lcd_display_current_character][3:0];
+				remote_access_lcd_enable_out_reg = 1;
+				lcd_display_wait_counter = 167;		// Wait 40uS
+				lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			31:begin
+				remote_access_lcd_enable_out_reg = 0;
+				lcd_display_wait_counter = lcd_display_wait_counter - 1;
+				if (lcd_display_wait_counter == 0) lcd_display_initialization_state = lcd_display_initialization_state + 1;
+			end
+			32:begin
+				lcd_display_current_character = lcd_display_current_character + 1;
+				lcd_display_initialization_state = lcd_display_initialization_state + 1;
+				if (lcd_display_current_character < 32) begin
+					lcd_display_initialization_state = 28;
+				end
+				if (lcd_display_current_character == 16) begin
+					if (lcd_display_line_two == 0) begin
+						lcd_display_line_two = 1;
+						lcd_display_initialization_state = 24;
+					end
+				end
+			end
+			33:begin
+				// End!
+				remote_access_lcd_rs_out_reg = 0;
+				remote_access_lcd_enable_out_reg = 0;
+				lcd_display_line_two = 0;
+				lcd_display_current_character = 0;
+				if (update_lcd_display == 1) begin
+					lcd_display_line_two = 0;
+					lcd_display_current_character = 0;
+					lcd_display_initialization_state = 24;
+					lcd_display_string[0] = received_lcd_display_string[0];
+					lcd_display_string[1] = received_lcd_display_string[1];
+					lcd_display_string[2] = received_lcd_display_string[2];
+					lcd_display_string[3] = received_lcd_display_string[3];
+					lcd_display_string[4] = received_lcd_display_string[4];
+					lcd_display_string[5] = received_lcd_display_string[5];
+					lcd_display_string[6] = received_lcd_display_string[6];
+					lcd_display_string[7] = received_lcd_display_string[7];
+					lcd_display_string[8] = received_lcd_display_string[8];
+					lcd_display_string[9] = received_lcd_display_string[9];
+					lcd_display_string[10] = received_lcd_display_string[10];
+					lcd_display_string[11] = received_lcd_display_string[11];
+					lcd_display_string[12] = received_lcd_display_string[12];
+					lcd_display_string[13] = received_lcd_display_string[13];
+					lcd_display_string[14] = received_lcd_display_string[14];
+					lcd_display_string[15] = received_lcd_display_string[15];
+					lcd_display_string[16] = received_lcd_display_string[16];
+					lcd_display_string[17] = received_lcd_display_string[17];
+					lcd_display_string[18] = received_lcd_display_string[18];
+					lcd_display_string[19] = received_lcd_display_string[19];
+					lcd_display_string[20] = received_lcd_display_string[20];
+					lcd_display_string[21] = received_lcd_display_string[21];
+					lcd_display_string[22] = received_lcd_display_string[22];
+					lcd_display_string[23] = received_lcd_display_string[23];
+					lcd_display_string[24] = received_lcd_display_string[24];
+					lcd_display_string[25] = received_lcd_display_string[25];
+					lcd_display_string[26] = received_lcd_display_string[26];
+					lcd_display_string[27] = received_lcd_display_string[27];
+					lcd_display_string[28] = received_lcd_display_string[28];
+					lcd_display_string[29] = received_lcd_display_string[29];
+					lcd_display_string[30] = received_lcd_display_string[30];
+					lcd_display_string[31] = received_lcd_display_string[31];
+				end
+			end
+		endcase
+	end
+endmodule
+
+module async_receiver(clk, RxD, RxD_data_ready, RxD_data, RxD_endofpacket, RxD_idle);
+	input clk, RxD;
+	output RxD_data_ready;  // onc clock pulse when RxD_data is valid
+	output [7:0] RxD_data;
+	
+	parameter ClkFrequency = 25000000;	// 25MHz
+	parameter Baud = 115200;
+	
+	// We also detect if a gap occurs in the received stream of characters
+	// That can be useful if multiple characters are sent in burst
+	//  so that multiple characters can be treated as a "packet"
+	output RxD_endofpacket;  // one clock pulse, when no more data is received (RxD_idle is going high)
+	output RxD_idle;  // no data is being received
+	
+	// Baud generator (we use 8 times oversampling)
+	parameter Baud8 = Baud*8;
+	parameter Baud8GeneratorAccWidth = 16;
+	wire [Baud8GeneratorAccWidth:0] Baud8GeneratorInc = ((Baud8<<(Baud8GeneratorAccWidth-7))+(ClkFrequency>>8))/(ClkFrequency>>7);
+	reg [Baud8GeneratorAccWidth:0] Baud8GeneratorAcc;
+	always @(posedge clk) Baud8GeneratorAcc <= Baud8GeneratorAcc[Baud8GeneratorAccWidth-1:0] + Baud8GeneratorInc;
+	wire Baud8Tick = Baud8GeneratorAcc[Baud8GeneratorAccWidth];
+	
+	////////////////////////////
+	reg [1:0] RxD_sync_inv;
+	always @(posedge clk) if(Baud8Tick) RxD_sync_inv <= {RxD_sync_inv[0], ~RxD};
+	// we invert RxD, so that the idle becomes "0", to prevent a phantom character to be received at startup
+	
+	reg [1:0] RxD_cnt_inv;
+	reg RxD_bit_inv;
+	
+	always @(posedge clk)
+	if(Baud8Tick)
+	begin
+		if( RxD_sync_inv[1] && RxD_cnt_inv!=2'b11) RxD_cnt_inv <= RxD_cnt_inv + 2'h1;
+		else 
+		if(~RxD_sync_inv[1] && RxD_cnt_inv!=2'b00) RxD_cnt_inv <= RxD_cnt_inv - 2'h1;
+	
+		if(RxD_cnt_inv==2'b00) RxD_bit_inv <= 1'b0;
+		else
+		if(RxD_cnt_inv==2'b11) RxD_bit_inv <= 1'b1;
+	end
+	
+	reg [3:0] state;
+	reg [3:0] bit_spacing;
+	
+	// "next_bit" controls when the data sampling occurs
+	// depending on how noisy the RxD is, different values might work better
+	// with a clean connection, values from 8 to 11 work
+	wire next_bit = (bit_spacing==4'd10);
+	
+	always @(posedge clk)
+	if(state==0)
+		bit_spacing <= 4'b0000;
+	else
+	if(Baud8Tick)
+		bit_spacing <= {bit_spacing[2:0] + 4'b0001} | {bit_spacing[3], 3'b000};
+	
+	always @(posedge clk)
+	if(Baud8Tick)
+	case(state)
+		4'b0000: if(RxD_bit_inv) state <= 4'b1000;  // start bit found?
+		4'b1000: if(next_bit) state <= 4'b1001;  // bit 0
+		4'b1001: if(next_bit) state <= 4'b1010;  // bit 1
+		4'b1010: if(next_bit) state <= 4'b1011;  // bit 2
+		4'b1011: if(next_bit) state <= 4'b1100;  // bit 3
+		4'b1100: if(next_bit) state <= 4'b1101;  // bit 4
+		4'b1101: if(next_bit) state <= 4'b1110;  // bit 5
+		4'b1110: if(next_bit) state <= 4'b1111;  // bit 6
+		4'b1111: if(next_bit) state <= 4'b0001;  // bit 7
+		4'b0001: if(next_bit) state <= 4'b0000;  // stop bit
+		default: state <= 4'b0000;
+	endcase
+	
+	reg [7:0] RxD_data;
+	always @(posedge clk)
+	if(Baud8Tick && next_bit && state[3]) RxD_data <= {~RxD_bit_inv, RxD_data[7:1]};
+	
+	reg RxD_data_ready;
+	always @(posedge clk)
+	begin
+		RxD_data_ready <= (Baud8Tick && next_bit && state==4'b0001 && ~RxD_bit_inv);  // ready only if the stop bit is received
+	end
+	
+	reg [4:0] gap_count;
+	always @(posedge clk) if (state!=0) gap_count<=5'h00; else if(Baud8Tick & ~gap_count[4]) gap_count <= gap_count + 5'h01;
+	assign RxD_idle = gap_count[4];
+	reg RxD_endofpacket; always @(posedge clk) RxD_endofpacket <= Baud8Tick & (gap_count==5'h0F);
+endmodule
+
+module async_transmit(clk, TxD_start, TxD_data, TxD, TxD_busy, state);
+	input clk, TxD_start;
+	input [7:0] TxD_data;
+	output TxD, TxD_busy;
+	output [4:0] state;
+	parameter ClkFrequency = 25000000;	// 25MHz
+	//parameter ClkFrequency = 50000000;	// 50MHz
+	parameter Baud = 115200;
+	parameter RegisterInputData = 1;	// in RegisterInputData mode, the input doesn't have to stay valid while the character is been transmitted
+	
+	// Baud generator
+	parameter BaudGeneratorAccWidth = 16;
+	reg [BaudGeneratorAccWidth:0] BaudGeneratorAcc;
+	`ifdef DEBUG
+	wire [BaudGeneratorAccWidth:0] BaudGeneratorInc = 17'h10000;
+	`else
+	wire [BaudGeneratorAccWidth:0] BaudGeneratorInc = ((Baud<<(BaudGeneratorAccWidth-4))+(ClkFrequency>>5))/(ClkFrequency>>4);
+	`endif
+	
+	wire BaudTick = BaudGeneratorAcc[BaudGeneratorAccWidth];
+	wire TxD_busy;
+	always @(posedge clk) if(TxD_busy) BaudGeneratorAcc <= BaudGeneratorAcc[BaudGeneratorAccWidth-1:0] + BaudGeneratorInc;
+	
+	// Transmitter state machine
+	reg [4:0] state;
+	wire TxD_ready = (state==0);
+	assign TxD_busy = ~TxD_ready;
+	
+	reg [7:0] TxD_dataReg;
+	always @(posedge clk) if(TxD_ready & TxD_start) TxD_dataReg <= TxD_data;
+	wire [7:0] TxD_dataD = RegisterInputData ? TxD_dataReg : TxD_data;
+	
+	always @(posedge clk) begin
+		if (TxD_start == 0) state <= 5'b00000;
+	
+		case(state)
+			5'b00000: if(TxD_start) state <= 5'b00001;
+			5'b00001: if(BaudTick) state <= 5'b00100;
+			5'b00100: if(BaudTick) state <= 5'b01000;  // start
+			5'b01000: if(BaudTick) state <= 5'b01001;  // bit 0
+			5'b01001: if(BaudTick) state <= 5'b01010;  // bit 1
+			5'b01010: if(BaudTick) state <= 5'b01011;  // bit 2
+			5'b01011: if(BaudTick) state <= 5'b01100;  // bit 3
+			5'b01100: if(BaudTick) state <= 5'b01101;  // bit 4
+			5'b01101: if(BaudTick) state <= 5'b01110;  // bit 5
+			5'b01110: if(BaudTick) state <= 5'b01111;  // bit 6
+			5'b01111: if(BaudTick) state <= 5'b00010;  // bit 7
+			5'b00010: if(BaudTick) state <= 5'b00011;  // stop1
+			//4'b0011: if(BaudTick) state <= 4'b0000;  // stop2
+			5'b00011: if(BaudTick) state <= 5'b10000;  // stop2
+			//default: if(BaudTick) state <= 4'b0000;
+		endcase
+	end
+	
+	// Output mux
+	reg muxbit;
+	always @( * )
+	case(state[2:0])
+		3'd0: muxbit <= TxD_dataD[0];
+		3'd1: muxbit <= TxD_dataD[1];
+		3'd2: muxbit <= TxD_dataD[2];
+		3'd3: muxbit <= TxD_dataD[3];
+		3'd4: muxbit <= TxD_dataD[4];
+		3'd5: muxbit <= TxD_dataD[5];
+		3'd6: muxbit <= TxD_dataD[6];
+		3'd7: muxbit <= TxD_dataD[7];
+	endcase
+	
+	// Put together the start, data and stop bits
+	reg TxD;
+	always @(posedge clk) TxD <= (state<4) | (state[3] & muxbit) | state[4];  // register the output to make it glitch free
+
+endmodule