8.

[poslink.git] / POSLink.v

diff --git a/POSLink.v b/POSLink.v
index 3dc9576ecc4ab11e9d325f85ac9c0cca24cb9feb..b53c08f52c53b31b4cde8ede3fbacc2938cc907f 100644 (file)
--- a/POSLink.v
+++ b/POSLink.v
@@ -1,46 +1,111 @@
 module POSLink(
        input xtal,
-       input [2:0] tos_inputs_e2,
-       input [3:0] sw,
-       output reg [3:0] leds,
-       output reg tos_output);
-       
-       reg [2:0] tos_inputs_e;
-       reg [2:0] tos_inputs;
-       wire [2:0] tos_good;
+       input [3:0] tos_inputs_e2,
+       input serial_e2,
+       input [1:0] buttons,
+       output tos_output,
+       output reg data_output,
+       output reg [3:0] anode,
+       output reg [7:0] cathode);
        
+       reg [3:0] tos_inputs_e;
+       reg [3:0] tos_inputs;
+       reg serial_e;
+       reg serial;
+
+       wire [3:0] tos_good;
+
+       /* Synchronize inputs */
        always @(posedge xtal) begin
                tos_inputs_e <= tos_inputs_e2;
                tos_inputs <= tos_inputs_e;
+               serial_e <= serial_e2;
+               serial <= serial_e;
        end
-       
-       /* 100ns -> 1000ns */
-       
+
+       wire [11:0] data;
+       wire data_good;
+
+       reg [1:0] seg;
+
+       always @(*)
+               case (seg)
+               2'b00:  anode = 4'b0111;
+               2'b01:  anode = 4'b1011;
+               2'b10:  anode = 4'b1101;
+               2'b11:  anode = 4'b1110;
+               endcase
+
+       reg [1:0] tos_select;
+
+       wire [3:0] current_bit;
+
+       assign tos_output = tos_inputs_e2[tos_select];
+
        always @(*) begin
-               leds[3:0] = 4'h0;
-               
-               if (sw[2] || (tos_good[2] && ~sw[1] && ~sw[0])) begin
-                       tos_output = tos_inputs[2];
-                       leds[2] = 1;
-               end else if (sw[1] | (tos_good[1] && ~sw[0])) begin
-                       tos_output = tos_inputs[1];
-                       leds[1] = 1;
-               end else if (sw[0] | tos_good[0]) begin
-                       tos_output = tos_inputs[0];
-                       leds[0] = 1;
-               end else
-                       tos_output = sw[3];
-               leds[3] = tos_output;
+               cathode = data[7:0];
+               seg = data[9:8];
+               tos_select = data[11:10];
        end
        
-       TOS_Detect detect[2:0](.xtal(xtal), .tos_input(tos_inputs), .tos_good(tos_good));
+       wire [5:0] output_stuff = { buttons, tos_good };
+
+       always @(*)
+               data_output = output_stuff[current_bit[2:0]];
+
+       TOS_Detect detect[3:0](.xtal(xtal), .tos_input(tos_inputs), .tos_good(tos_good));
+       POS_Serial serinput(.xtal(xtal), .serial(serial), .data_reg(data), .current_bit(current_bit), .data_good(data_good));
+endmodule
+
+
+module POS_Serial(
+       input xtal,
+       input serial,
+       output reg [11:0] data_reg = 0,
+       output reg [3:0] current_bit = 0,
+       output reg data_good = 0);
+
+       reg serial_1a;
+
+       always @(posedge xtal)
+               serial_1a = serial;
+
+       wire edge_detect = serial ^ serial_1a;
+
+       reg [4:0] edge_counter = 0;
+
+       always @(posedge xtal) begin
+               data_good = 0;
+
+               if (edge_detect) begin
+                       if (edge_counter == 31) begin
+                               current_bit = 0;
+                               data_reg = 0;
+                       end else begin
+               //              data_reg[11:1] = data_reg[10:0];
+               //              data_reg[0] = (edge_counter > 20);
+                               data_reg[current_bit] = (edge_counter > 20);
+                               if (current_bit == 11) begin
+                                       data_good = 1;
+                                       current_bit = 0;
+                               end else
+                                       current_bit = current_bit + 1;
+                       end
+
+                       edge_counter = 0;
+               end else begin
+                       if (edge_counter != 31)
+                               edge_counter = edge_counter + 1;
+               end
+       end
 endmodule
 
-/* xtal: 50MHz (==20ns)
- * Minimum: 100ns (we'll allow 60ns for good measure)
- *          5 cycles (we'll allow 3 for good measure)
- * Maximum: 1000ns (we'll allow 1200ns for good measure)
- *          50 cycles (we'll allow 60 for good measure)
+
+/* xtal: 25MHz (==40ns)
+ * Minimum: 100ns
+ *          2 cycles (80 ns)
+ * Maximum: 1000ns
+ *          25 cycles (we'll allow 30 = 1200ns for good measure)
  */
 module TOS_Detect(
        input xtal,
@@ -52,21 +117,22 @@ module TOS_Detect(
                tos_input_1a <= tos_input;
        wire transition = tos_input ^ tos_input_1a;
        
-       reg [5:0] lasttx = 0;
+       reg [3:0] lasttx = 0;
        always @(posedge xtal) begin
                if (transition) begin
-                       if (lasttx < 3) /* Too soon! */
+                       if (lasttx < 2) /* Too soon! */
                                tos_good <= 0;
-                       else if (lasttx > 60) /* Too late! */
+                       else if (lasttx > 30) /* Too late! */
                                tos_good <= 0;
                        else /* OK by me. */
                                tos_good <= 1;
                        lasttx <= 0;
                end else begin
-                       if (lasttx != 63)
+                       if (lasttx != 31)
                                lasttx <= lasttx + 1;
                        else
                                tos_good <= 0;
                end
        end
 endmodule
+