module uart_top(
	input                        clk,
	input                        rst,
	input                        uart_rx,
	output                       uart_tx
);

parameter                        CLK_FRE  = 27_000_000; // Mhz
parameter                        UART_FRE = 115200;     // Baud

localparam                       IDLE =  0;
localparam                       SEND =  1;   // send 
localparam                       WAIT =  2;   // wait 1 second and send uart received data

reg[7:0]                         tx_data;
reg[7:0]                         tx_str;
reg                              tx_data_valid;
wire                             tx_data_ready;
reg[7:0]                         tx_cnt;

wire[7:0]                        rx_data;
wire                             rx_data_valid;
wire                             rx_data_ready;

reg[31:0]                        wait_cnt;
reg[3:0]                         state;

wire rst_p = rst;

assign rx_data_ready = 1'b1;    //always can receive data,

always@(posedge clk or negedge rst_p)
begin
	if(rst_p == 1'b1)
	begin
		wait_cnt <= 32'd0;
		tx_data <= 8'd0;
		state <= IDLE;
		tx_cnt <= 8'd0;
		tx_data_valid <= 1'b0;
	end
	else
	case(state)
		IDLE:begin
			state <= SEND;
        end

		SEND:begin
			wait_cnt <= 32'd0;
			tx_data <= tx_str;

			if(tx_data_valid == 1'b1 && tx_data_ready == 1'b1 && tx_cnt < DATA_NUM - 1)//Send 12 bytes data
			begin
				tx_cnt <= tx_cnt + 8'd1; //Send data counter
			end
			else if(tx_data_valid && tx_data_ready)//last byte sent is complete
			begin
				tx_cnt <= 8'd0;
				tx_data_valid <= 1'b0;
				state <= WAIT;
			end
			else if(~tx_data_valid)
			begin
				tx_data_valid <= 1'b1;
			end
		end

		WAIT:begin
			wait_cnt <= wait_cnt + 32'd1;

			if(rx_data_valid == 1'b1)
			begin
				tx_data_valid <= 1'b1;
				tx_data <= rx_data;   // send uart received data
			end
			else if(tx_data_valid && tx_data_ready)
			begin
				tx_data_valid <= 1'b0;
			end
			else if(wait_cnt >= CLK_FRE * 1000_000) // wait for 1 second
				state <= SEND;
		end
        
		default:
			state <= IDLE;
	endcase
end

always@(*)
	tx_str <= send_data[(DATA_NUM - 1 - tx_cnt) * 8 +: 8];

uart_rx#
(
	.CLK_FRE(CLK_FRE),
	.BAUD_RATE(UART_FRE)
) uart_rx_inst
(
	.clk                        (clk),
	.rst_p                      (rst_p),
	.rx_data                    (rx_data),
	.rx_data_valid              (rx_data_valid),
	.rx_data_ready              (rx_data_ready),
	.rx_pin                     (uart_rx)
);

uart_tx#
(
	.CLK_FRE(CLK_FRE),
	.BAUD_RATE(UART_FRE)
) uart_tx_inst
(
	.clk                        (clk),
	.rst_p                      (rst_p),
	.tx_data                    (tx_data),
	.tx_data_valid              (tx_data_valid),
	.tx_data_ready              (tx_data_ready),
	.tx_pin                     (uart_tx)
);
endmodule