Fix 7-segment LED display and add sample driver for the same

2 files changed, 67 insertions, 12 deletions

diff --git a/fpga/xilinx/digilent/spartan_6/s6_remotefpga_test/main.ucf b/fpga/xilinx/digilent/spartan_6/s6_remotefpga_test/main.ucf
index ab433e5..c9a68dd 100644
--- a/fpga/xilinx/digilent/spartan_6/s6_remotefpga_test/main.ucf
+++ b/fpga/xilinx/digilent/spartan_6/s6_remotefpga_test/main.ucf
@@ -1,8 +1,8 @@
 # (c) 2013 Timothy Pearson, Raptor Engineering
 # Released into the Public Domain
 
-NET "clk"  LOC = "V10";
+NET "clk"  LOC = "V10" | IOSTANDARD = "LVCMOS33";
 TIMESPEC TS_clk = PERIOD clk 100000 kHz;
 
-NET "serial_input"  LOC = "T12";
-NET "serial_output"  LOC = "M10";
+NET "serial_input"  LOC = "T12" | IOSTANDARD = "LVCMOS33";
+NET "serial_output"  LOC = "M10" | IOSTANDARD = "LVCMOS33";
diff --git a/fpga/xilinx/digilent/spartan_6/s6_remotefpga_test/main.v b/fpga/xilinx/digilent/spartan_6/s6_remotefpga_test/main.v
index 801a9aa..6162ec1 100644
--- a/fpga/xilinx/digilent/spartan_6/s6_remotefpga_test/main.v
+++ b/fpga/xilinx/digilent/spartan_6/s6_remotefpga_test/main.v
@@ -40,6 +40,9 @@ module main(
 	wire [5:0] lcd_data_in_address;

 	wire [7:0] lcd_data_in_data;

 	wire lcd_data_in_enable;

+

+	wire [7:0] led_segment_bus;

+	wire [3:0] led_digit_select;

 	

 	//-------------------------------------------------------------------------------------------------------

 	//

@@ -69,9 +72,9 @@ module main(
 	//

 	// Inputs:

 	// .clk: 							50MHz clock

-	// .4_bit_input							4-bit input to the user program from the remote access module 

-	// .8_bit_input							8-bit input to the user program from the remote access module 

-	// .16_bit_input						16-bit input to the user program from the remote access module

+	// .four_bit_input						4-bit input to the user program from the remote access module 

+	// .eight_bit_input						8-bit input to the user program from the remote access module 

+	// .sixteen_bit_input						16-bit input to the user program from the remote access module

 	// .serial_port_receiver					Input from the serial port's RxD (receive data) pin

 	// .remote_access_input_enable					Toggle remote access input vs. local input mode

 	// .local_input							Local input to the remote program 

@@ -90,9 +93,9 @@ module main(
 	// .led_digit_select						Connect directly to the 4 bits enabling the LED display digits

 	//

 	// Outputs:

-	// .4_bit_output						4-bit output from the user program to the remote access module

-	// .8_bit_output						8-bit output from the user program to the remote access module

-	// .16_bit_output						16-bit output from the user program to the remote access module

+	// .four_bit_output						4-bit output from the user program to the remote access module

+	// .eight_bit_output						8-bit output from the user program to the remote access module

+	// .sixteen_bit_output						16-bit output from the user program to the remote access module

 	// .lcd_data_out						Data output to the LCD

 	// .lcd_rs_out							RS signal output to the LCD

 	// .lcd_rw_out							RW signal output to the LCD

@@ -131,7 +134,7 @@ module main(
 		.lcd_data_in_address(lcd_data_in_address), .lcd_data_in_data(lcd_data_in_data), .lcd_data_in_enable(lcd_data_in_enable),

 		.sram_wren_in(sram_wren_in), .sram_clock_in(sram_clock_in), .sram_data_in(sram_data_in), .sram_address_in(sram_address_in),

 		.sram_data_out(sram_data_out), .sram_available(sram_available), .sram_processing_done(sram_processing_done),

-		.led_segment_bus(255), .led_digit_select(15));

+		.led_segment_bus(led_segment_bus), .led_digit_select(led_digit_select));

 	

 	assign remote_access_local_input[7:4] = 0;					// Local inputs

 	assign remote_access_local_input[3:0] = 0;					// Local inputs

@@ -153,7 +156,8 @@ module main(
 	sample_demo sample_demo(.clk(clk_div_by_two), .four_bit_input(four_bit_input), .four_bit_output(four_bit_output),

 		.eight_bit_input(eight_bit_input), .eight_bit_output(eight_bit_output), .sixteen_bit_input(sixteen_bit_input),

 		.sixteen_bit_output(sixteen_bit_output), .lcd_data_in_address(lcd_data_in_address),

-		.lcd_data_in_data(lcd_data_in_data), .lcd_data_in_enable(lcd_data_in_enable));

+		.lcd_data_in_data(lcd_data_in_data), .lcd_data_in_enable(lcd_data_in_enable),

+		.led_segment_bus(led_segment_bus), .led_digit_select(led_digit_select));

 

 	//-------------------------------------------------------------------------------------------------------

 	//

@@ -174,7 +178,7 @@ endmodule
 //

 //-------------------------------------------------------------------------------------------------------

 

-module sample_demo(clk, four_bit_input, four_bit_output, eight_bit_input, eight_bit_output, sixteen_bit_input, sixteen_bit_output, lcd_data_in_address, lcd_data_in_data, lcd_data_in_enable);

+module sample_demo(clk, four_bit_input, four_bit_output, eight_bit_input, eight_bit_output, sixteen_bit_input, sixteen_bit_output, lcd_data_in_address, lcd_data_in_data, lcd_data_in_enable, led_segment_bus, led_digit_select);

 	input clk;

 	

 	input [3:0] four_bit_input;

@@ -188,6 +192,9 @@ module sample_demo(clk, four_bit_input, four_bit_output, eight_bit_input, eight_
 	output reg [7:0] lcd_data_in_data;

 	output reg lcd_data_in_enable;

 

+	output reg [7:0] led_segment_bus;

+	output reg [3:0] led_digit_select;

+

 	reg [7:0] lcd_sample_counter = 48;							// Create a sample LCD display counter register

 	reg [31:0] lcd_character_change_timer = 0;						// Wait a certain number of cycles before loading a new character

 	reg [5:0] lcd_current_character = 0;							// The current character's address

@@ -218,6 +225,54 @@ module sample_demo(clk, four_bit_input, four_bit_output, eight_bit_input, eight_
 			end

 		end

 	end

+

+	// 7-segment LED display driver clock generator

+	reg sseg_clock;

+	reg [4:0] sseg_clock_counter;

+

+	always @(posedge clk) begin

+		sseg_clock_counter = sseg_clock_counter + 1;

+		if (sseg_clock_counter > 16) begin

+			sseg_clock_counter = 0;

+			sseg_clock = ~sseg_clock;

+		end

+	end

+

+	// 7-segment LED display driver

+	// led_segment_bus and led_digit_select are active low

+	// The bit sequence, MSB to LSB, is dp a b c d e f g

+	// Segment letters are taken from ug130.pdf page 15

+

+	// 0: 8'b10000001

+	// 1: 8'b11001111

+	// 2: 8'b10010010

+	// 3: 8'b10000110

+	reg [2:0] current_anode;

+	always @(posedge sseg_clock) begin

+		current_anode = current_anode + 1;

+		if (current_anode > 3) begin

+			current_anode = 0;

+		end

+

+		case (current_anode)

+			0: begin

+				led_digit_select = 4'b1110;

+				led_segment_bus = 8'b10000001;

+			end

+			1: begin

+				led_digit_select = 4'b1101;

+				led_segment_bus = 8'b11001111;

+			end

+			2: begin

+				led_digit_select = 4'b1011;

+				led_segment_bus = 8'b10010010;

+			end

+			3: begin

+				led_digit_select = 4'b0111;

+				led_segment_bus = 8'b10000110;

+			end

+		endcase

+	end

 endmodule

 

 //-------------------------------------------------------------------------------------------------------