IR frequency counter

`timescale 1ns / 1ps

// add in the no data display
// Infrared Frequency detection and display

// Version 4: removed HZLED funcionality
//              -changed freq_confirm to 2 bit var (from 1 bit), keeps track of which mailbox as well as confirms
//              -changed else block to conditional upon RM state. Makes sure freq_confirm keeps driving until mail is delivered
//              -ADDED ANOTHER IRsignal input!!
// also, saved over V3... might need to go back to group folder and redownload
// MAJOR CHOICE: keep L and R identification here
//      OR: revert back to only one sided inputs and let state machine decide which side!!!!!!
module IR_frequency(
    input clk,
    //input [1:0] whisker, // MAYBE NEED THIS FOR DETERMINING WHICH SIGNAL TO TAKE IN
    input [1:0] IRsignal, // MSB = left side, LSB = right side!!!!!!
    input [1:0] state,
    //output reg LED10, LED100, LED1k,    // to differentiate which frequency easily
    //output reg [2:0] HzLED, // 000 off, 001 10Hz, 010 100 Hz, 100 1kHz
    output reg [1:0] freq_confirm // 0 = off, 1 = 10 Hz, 2 = 100 Hz, 3 = 1Khz
    );


// Going to confirm the mailbox by polling twice.
// 10-1k Hz going to be chosen from 3 different ranges.


// previous variables: no _L or _R, IRsignal was 1 bit, so was prevIR

reg [26:0] fr_count; // counting up to 100 million
reg [1:0] last;
reg [10:0] data_store;  // register to count data, data/8 = hertz/8
reg [16:0] data;   // LSB side of IRsignal input
// changed mailbox/prevmailbox from 3 bit to 2 bit
reg [1:0] mailbox;
reg [1:0] prev_mailbox; // to compare current mailbox with for confirmation
reg IR;
reg prevIR;

initial begin
    {fr_count, last, data_store, data, mailbox, prev_mailbox, IR, prevIR} = 0;
end

always@(posedge clk)
    begin
        if(state == 1)  begin
            //freq_confirm = 0;  // always zero unless confirm var.
            fr_count <= fr_count + 1;
            prevIR <= IR;
            IR <= IRsignal;
            if(IR && !prevIR)
                data <= data + 1;
            //data <= (IR && !prevIR)? data + 1 : data;
                data_store = data*5;
            //if(fr_count == 100000000) begin // 100 MHz
            if(fr_count == 20000000) begin  // 100 MHz / 8 --->!!!1 maybe switch to 1 fifth!!
                //poll_flag = 1;    // with it edited out, don't gotta worry about 7-seg
                fr_count <= 0;
                // NOTE: data_store, mailbox, and prev_mailbox all must have blocking assignments
                data_store = data * 5;
                //data_store_R = data_R * 5;
                data <= 0;
                // mailbox is current selection
                prev_mailbox = mailbox;
                mailbox =    ((data_store >= 8) && (data_store <= 20)) ? 1 :
                            ((data_store >= 80) && (data_store <= 200)) ? 2 :
                            ((data_store >= 800) && (data_store <= 1200)) ? 3 : 0;
                if((prev_mailbox == mailbox) && mailbox != 0) begin
                    freq_confirm = mailbox;  // frequency has been confirmed
                    // remobed HzLED variable, freq_confirm does all of it now
                    //HzLED <= mailbox;   // 3 bit mailbox feeds directly into HzLED's to show user
                end
                else
                    freq_confirm = 0;
            end
        end // end IR state
        else if(state == 0) begin   // in RM state

            //HzLED <= HzLED; // keeps on previously confirmed lights
            // HZLED TYPE VARIABLE REQUIRED TO KEEP DRIVING AN LED
            // SINCE FREQ CONFIRM MUST GO BACK TO 0 AFTER CONFIRMATION!!!
            freq_confirm <= 0;  // confirm flag needs to be reset for next IR state
        end

    end


endmodule


// instead of rising/falling edge, every clock tick check IR signal
// previous IR signal, current IR signal.
// set both to zero
// if(IRsignal && !prevIR) --> data <= data + 1;