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hex_decoder.v
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hex_decoder.v
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// SPI OLED SSD1331 display HEX decoder core
// AUTHOR=EMARD
// LICENSE=BSD
// keep en=1 to show OLED screen
module hex_decoder
#(
parameter C_data_len = 8, // input bits report len
parameter C_debounce = 1'b0,
parameter C_font_file = "oled_font.mem",
parameter C_font_size = 136,
// Useful values of C_data_len: 4,8,16,32,64,128,192,256,320,448,512
// Display has 8 lines. Each line has 16 HEX digits or 64 bits.
// C_data_len(63 downto 0) is shown on the first line
// C_data_len(127 downto 64) is shown on second line etc.
parameter C_color_bits = 16,
parameter C_x_bits = 8, // X screen bits
parameter C_y_bits = 7 // Y screen bits
)
(
input wire clk, // 1-25 MHz clock typical
input wire en, // 1-enable/0-hold input for button or other purpose
input wire [C_data_len-1:0] data,
input wire [C_x_bits-1:0] x,
input wire [C_y_bits-1:0] y,
input wire next_pixel,
output wire [C_color_bits-1:0] color
);
reg [4:0] C_oled_font[0:C_font_size-1];
initial
begin
$readmemb(C_font_file, C_oled_font);
end
reg [C_data_len-1:0] R_data;
// reg R_dc = 1'b0; // 0-command, 1-data
localparam C_holding_bits = 23;
reg [C_holding_bits-1:0] R_holding = 0; // debounce counter
reg R_go = 1'b1;
reg [9:0] R_increment = 10'b0000000001; // fitted to start from char index 0
// alias S_column: std_logic_vector(3 downto 0) is R_increment(3 downto 0);
wire [3:0] S_column = R_increment[3:0];
// alias S_scanline: std_logic_vector(2 downto 0) is R_increment(6 downto 4);
wire [2:0] S_scanline = R_increment[6:4];
// alias S_row: std_logic_vector(2 downto 0) is R_increment(9 downto 7);
wire [2:0] S_row = R_increment[9:7];
reg [2:0] R_cpixel = 1; // fitted to start with first pixel
localparam C_char_line_bits = 5;
reg [C_char_line_bits-1:0] R_char_line = 5'b01110;
// signal R_cpixel: integer range 0 to 6; -- pixel counter
wire [C_color_bits-1:0] S_pixel;
reg [C_color_bits-1:0] R_pixel;
reg [6:0] R_data_index = 7'b0000010; // tuned to start at 1st hex digit
reg [3:0] R_indexed_data; // stored from input
wire [3:0] S_indexed_data;
// RGB332
// red 20 40 80
// green 04 08 10
// blue 01 02
// RGB565
// red 0800 1000 2000 4000 8000
// green 0020 0040 0080 0100 0200 0400
// blue 0001 0002 0004 0008 0010
localparam C_color_black = C_color_bits < 12 ? 8'h00 : 16'h0000 ;
localparam C_color_dark_red = C_color_bits < 12 ? 8'h40 : 16'h4000 ;
localparam C_color_dark_brown = C_color_bits < 12 ? 8'h44 : 16'h2100 ;
localparam C_color_dark_yellow = C_color_bits < 12 ? 8'h48 : 16'h4200 ;
localparam C_color_dark_green = C_color_bits < 12 ? 8'h08 : 16'h0200 ;
localparam C_color_dark_cyan = C_color_bits < 12 ? 8'h05 : 16'h0208 ;
localparam C_color_dark_blue = C_color_bits < 12 ? 8'h01 : 16'h0008 ;
localparam C_color_dark_violett = C_color_bits < 12 ? 8'h21 : 16'h4008 ;
localparam C_color_gray = C_color_bits < 12 ? 8'h45 : 16'h630C ;
localparam C_color_light_red = C_color_bits < 12 ? 8'h80 : 16'h8000 ;
localparam C_color_orange = C_color_bits < 12 ? 8'h84 : 16'h4200 ;
localparam C_color_light_yellow = C_color_bits < 12 ? 8'h90 : 16'h8400 ;
localparam C_color_light_green = C_color_bits < 12 ? 8'h10 : 16'h0400 ;
localparam C_color_light_cyan = C_color_bits < 12 ? 8'h0A : 16'h0410 ;
localparam C_color_light_blue = C_color_bits < 12 ? 8'h02 : 16'h0010 ;
localparam C_color_light_violett = C_color_bits < 12 ? 8'h42 : 16'h8010 ;
localparam C_color_white = C_color_bits < 12 ? 8'hFF : 16'hFFFF ;
wire [C_color_bits-1:0] C_color_map[0:15]; // char background color map
assign C_color_map[0] = C_color_black;
assign C_color_map[1] = C_color_dark_red;
assign C_color_map[2] = C_color_dark_brown;
assign C_color_map[3] = C_color_dark_yellow;
assign C_color_map[4] = C_color_dark_green;
assign C_color_map[5] = C_color_dark_cyan;
assign C_color_map[6] = C_color_dark_blue;
assign C_color_map[7] = C_color_dark_violett;
assign C_color_map[8] = C_color_gray;
assign C_color_map[9] = C_color_light_red;
assign C_color_map[10] = C_color_orange;
assign C_color_map[11] = C_color_light_yellow;
assign C_color_map[12] = C_color_light_green;
assign C_color_map[13] = C_color_light_cyan;
assign C_color_map[14] = C_color_light_blue;
assign C_color_map[15] = C_color_light_violett;
reg [C_color_bits-1:0] R_indexed_color;
generate
if(C_debounce == 1'b1)
always @(posedge clk) begin
if (en == 1'b1)
begin
if(R_holding[C_holding_bits-1] == 1'b0)
R_holding <= R_holding + 1;
end
else
R_holding <= 0;
// filter out single keypress (10 ms) or hold (1 sec)
// if(R_holding == 65536 || R_holding[C_holding_bits-1] == 1'b1) // 25mhz
if(R_holding == 32768 || R_holding[C_holding_bits-1] == 1'b1)
R_go <= 1'b1;
else
R_go <= 1'b0;
end // always
else
always @(posedge clk)
R_go <= en;
endgenerate
// S_pixel <= x"FF" when R_char_line(R_char_line'high) = '1' else R_indexed_color; -- scan left to right
assign S_pixel = R_char_line[0] == 1'b1 ? C_color_white : R_indexed_color; // scan right to left (white on color background)
// S_pixel <= x"FF" when R_char_line(0) = '1' else x"00"; -- scan right to left (white on black)
assign S_indexed_data = R_data[ {R_data_index, 2'd0} +: 4 ];
reg [10:0] R_counter;
always @(posedge clk) begin
if (next_pixel) begin // next pixel appears every 16th clock cycle
if (x >= 1 && x < 6 && y>=71 && y <79 )
begin
// pixel data
R_pixel <= S_pixel;
if(R_cpixel == 3)
R_data_index <= { S_row, S_column };
if(R_cpixel == 4)
R_indexed_data <= S_indexed_data;
if(R_cpixel == 5) // load new hex digit
begin
R_cpixel <= 0;
R_indexed_color <= C_color_map[R_indexed_data];
R_char_line <= C_oled_font[ {R_indexed_data, S_scanline} ];
R_increment <= R_increment + 1; // increment for column and scan line
if(R_increment == 0 && R_go == 1'b1)
R_data <= data; // sample data
end
else
begin
// R_char_line <= R_char_line(R_char_line'high-1 downto 0) & '0'; -- scan left to right
R_char_line <= { 1'b0, R_char_line[C_char_line_bits-1:1] }; // scan right to left
R_cpixel <= R_cpixel + 1;
end
end
else
begin
R_pixel <= C_color_black;
end
end
end
assign color = R_pixel;
endmodule