fpga tdc verilog

FPGA TDC (Time-to-Digital Converter) in Verilog is a digital circuit design that converts time intervals into digital values. It is commonly used in various applications, such as time-of-flight measurement, high-speed communication, and signal processing.

The Verilog code for an FPGA TDC typically involves the following components:

1. A clock signal generator: This generates a high-frequency clock signal that is used to measure time intervals.

2. A counter: This counts the number of clock cycles between two events, such as the rising edges of two signals.

3. A latch: This stores the counter value when the second event occurs.

4. A comparator: This compares the values of two latches to determine the time interval between the two events.

5. A digital output: This outputs the digital value of the time interval.

Here is a sample Verilog code for a simple FPGA TDC:

module tdc(clk, start, stop, output);

input clk, start, stop;
output reg [15:0] output;

reg [15:0] counter;
reg [15:0] latch;

always @(posedge clk) begin
    if (start) begin
        counter <= 0;
    end else if (stop) begin
        latch <= counter;
    end else begin
        counter <= counter + 1;
    end
end

always @(posedge clk) begin
    if (stop) begin
        output <= latch;
    end
end

endmodule

In this code, the input signals `start` and `stop` indicate the start and stop events, respectively. The `counter` register counts the number of clock cycles between these events, and the `latch` register stores the counter value when the stop event occurs.

The output signal `output` represents the digital value of the time interval, which is computed by subtracting the latch value from the counter value. Note that the code assumes that the clock signal has a fixed and known frequency, which is used to scale the counter value into time units.