module ledblink (CLKin, CLKout, SI, SO, CS, LED);

input CLKin;
output CLKout;
reg CLKout;
reg [2:0] CNT; // Counter for counting to 8 
reg [15:0] ADDRESS; // Address
reg [3:0] COUNTER;
reg [7:0] DATA; // Data to write
reg [7:0] DATAIN; 
reg [2:0] STATE; // State, 1 = Instruction, 2 + 3 = 16 bit Address, 4 = Byte to write
reg WRBIT; // 1 for write, 0 for read
reg [2:0] COUNTCLK;

output SI; // Data to sram
reg SI;
output CS; // Chip select
reg CS;
input SO;
output LED;
reg LED;

initial CNT = 1'b0;
initial STATE = 1'b0;
initial SI = 1'b1;
initial ADDRESS = 16'b0000000000001110;
initial COUNTER = 4'd15;
initial DATA = 8'b10101010;
initial CS = 1'b1;
initial DATAIN = 8'b00000000;
initial WRBIT = 1'b1;
initial LED = 1'b0;
initial CLKout = 1'b0;
initial COUNTCLK = 1'b0;

always @ (posedge CLKout)
begin
  CNT = CNT + 1'b1;
    
  if (STATE == 0) begin
    CS = 1'b0;
    CNT = 3'd7;
    STATE = STATE + 1'b1;
    SI = 1'b0;
  end  
  else if (STATE == 1) begin // Write Instruction
    if (CNT == 0) SI = 1'b0;
    if (CNT == 6) SI = 1'b1;
    if (CNT == 7) begin
      if (WRBIT == 1) SI = 1'b0;
      STATE = STATE + 1'b1;
    end
  end
  else if (STATE == 2) begin // 16 bit Address 
     SI = ADDRESS[COUNTER];
     COUNTER = COUNTER - 1'b1;
     if (COUNTER == 15) begin
       STATE = STATE + 1'b1;
       COUNTER = 7; // Re-assign address count to data counter
     end
  end  
  else if (STATE == 3) begin
    if (WRBIT == 1) SI = DATA[COUNTER];
    if (WRBIT == 0) DATAIN[COUNTER] = SO;
    COUNTER = COUNTER - 1'b1;
    if (CNT == 7) begin
       STATE = STATE + 1'b1;
    end
  end      
  else if (STATE == 4) begin
     SI = 1'b1;
     CS = 1'b1;
     STATE = 1'b0;
     WRBIT = WRBIT + 1'b1;
     if (DATAIN == DATA) LED = 1'b1;
     else LED = 1'b0;
  end 
  else STATE = STATE + 1'b1;
end

always @ (posedge CLKin)
begin
  COUNTCLK = COUNTCLK + 1'b1;
  if (COUNTCLK == 7) CLKout = ~CLKout;
end
endmodule