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 = 4'hF,
+ output reg [7:0] cathode = 8'hFF);
+ 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 [4:0] edge_counter;
+ 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
+
+ // Buttons are active-low, so invert them.
+ wire [7:0] output_stuff = { 2'b0, ~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), .edge_counter(edge_counter));
+endmodule
+
+
+module POS_Serial(
+ input xtal,
+ input serial,
+ output reg [11:0] data_reg = 0,
+ output reg [3:0] current_bit = 0,
+ output reg [4:0] edge_counter = 0,
+ output reg data_good = 0);
+
+ reg serial_1a;
+
+ always @(posedge xtal)
+ serial_1a <= serial;
+
+ wire edge_detect = serial ^ serial_1a;
+
+
+ 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) ? 1'b1 : 1'b0);
+ if (current_bit == 11) begin
+ 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
-
- TOS_Detect detect[2:0](.xtal(xtal), .tos_input(tos_inputs), .tos_good(tos_good));
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,
tos_input_1a <= tos_input;
wire transition = tos_input ^ tos_input_1a;
- reg [5:0] lasttx = 0;
+ reg [4:0] 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
+