/*
 * main_xula2.v
 *
 * Copyright: (C) 2013 LeafLabs, LLC
 * License: MIT License (See LICENSE file)
 * Author: Bryan Newbold <bnewbold@leaflabs.com>
 * Date: October 2013
 *
 * This is the top-level module for the Xess Corp Xula 2 development board.
 *
 * TODO if using this as a template for another design:
 *  - use a clock buffer, even if sticking with 12mhz
 */

module main (
    input wire clock_12mhz,
    inout wire [31:0] chan,
    inout wire chan_clk,

    //// Flash and microSD I/O
    output wire microsd_cs,
    output wire flash_cs,
    output wire flash_sclk,
    output wire flash_mosi,
    output wire flash_miso
    );

wire reset = chan[0];
wire uart_rx = chan[17];
wire uart_tx = chan[18];

reg [22:0] throb_counter = 0;
reg throb_led = 0;
assign chan[10] = throb_led;

wire [7:0] rx_byte;
wire [7:0] tx_byte;
wire uart_flag;
simple_uart #(
    .CLOCK_DIVIDE(313) // for 12MHz clock
) simple_uart_inst (
    .clk(clock_12mhz),
    .rst(reset),
    .rx(chan[17]),
    .tx(chan[18]),
    .transmit(uart_flag),
    .tx_byte(tx_byte),
    .received(uart_flag),
    .rx_byte(rx_byte),
    .is_receiving(),
    .is_transmitting(),
    .recv_error()
    );

rot13 rot13_inst (
    .clock(clock_12mhz),
    .reset(reset),
    .in_char(rx_byte),
    .out_char(tx_byte)
    );

always @(posedge clock_12mhz) begin
    if (reset) begin
        throb_counter <= 0;
        throb_led <= 0;
    end else begin
        if (throb_counter >= 23'd06_000_000) begin
            throb_led <= !throb_led;
            throb_counter <= 23'd0;
        end else begin
            throb_counter <= throb_counter + 23'd1;
        end
    end
end

// Tie off unused outputs
assign microsd_cs = 1'bZ;
assign flash_cs = 1'bZ;
assign flash_sclk = 1'bZ;
assign flash_mosi = 1'bZ;
assign flash_miso = 1'bZ;

// Squelch unused input warnings
(* KEEP="TRUE" *) wire dummy;
assign dummy =& {chan[31:0], chan_clk};

endmodule