////////////////////////////////////////////////////////////////////// //// //// //// raminfr.v //// //// //// //// //// //// This file is part of the "UART 16550 compatible" project //// //// http://www.opencores.org/cores/uart16550/ //// //// //// //// Documentation related to this project: //// //// - http://www.opencores.org/cores/uart16550/ //// //// //// //// Projects compatibility: //// //// - WISHBONE //// //// RS232 Protocol //// //// 16550D uart (mostly supported) //// //// //// //// Overview (main Features): //// //// Inferrable Distributed RAM for FIFOs //// //// //// //// Known problems (limits): //// //// None . //// //// //// //// To Do: //// //// Nothing so far. //// //// //// //// Author(s): //// //// - gorban@opencores.org //// //// - Jacob Gorban //// //// //// //// Created: 2002/07/22 //// //// Last Updated: 2002/07/22 //// //// (See log for the revision history) //// //// //// //// //// ////////////////////////////////////////////////////////////////////// //// //// //// Copyright (C) 2000, 2001 Authors //// //// //// //// This source file may be used and distributed without //// //// restriction provided that this copyright statement is not //// //// removed from the file and that any derivative work contains //// //// the original copyright notice and the associated disclaimer. //// //// //// //// This source file is free software; you can redistribute it //// //// and/or modify it under the terms of the GNU Lesser General //// //// Public License as published by the Free Software Foundation; //// //// either version 2.1 of the License, or (at your option) any //// //// later version. //// //// //// //// This source is distributed in the hope that it will be //// //// useful, but WITHOUT ANY WARRANTY; without even the implied //// //// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR //// //// PURPOSE. See the GNU Lesser General Public License for more //// //// details. //// //// //// //// You should have received a copy of the GNU Lesser General //// //// Public License along with this source; if not, download it //// //// from http://www.opencores.org/lgpl.shtml //// //// //// ////////////////////////////////////////////////////////////////////// // // CVS Revision History // // $Log: raminfr.v,v $ // Revision 1.2 2002/07/29 21:16:18 gorban // The uart_defines.v file is included again in sources. // // Revision 1.1 2002/07/22 23:02:23 gorban // Bug Fixes: // * Possible loss of sync and bad reception of stop bit on slow baud rates fixed. // Problem reported by Kenny.Tung. // * Bad (or lack of ) loopback handling fixed. Reported by Cherry Withers. // // Improvements: // * Made FIFO's as general inferrable memory where possible. // So on FPGA they should be inferred as RAM (Distributed RAM on Xilinx). // This saves about 1/3 of the Slice count and reduces P&R and synthesis times. // // * Added optional baudrate output (baud_o). // This is identical to BAUDOUT* signal on 16550 chip. // It outputs 16xbit_clock_rate - the divided clock. // It's disabled by default. Define UART_HAS_BAUDRATE_OUTPUT to use. // //Following is the Verilog code for a dual-port RAM with asynchronous read. module raminfr(clk, we, a, dpra, di, dpo); parameter addr_width = 4; parameter data_width = 8; parameter depth = 16; input clk; input we; input [(addr_width - 1):0] a; input [(addr_width - 1):0] dpra; input [(data_width - 1):0] di; output [(data_width - 1):0] dpo; reg [(data_width - 1):0] ram[(depth - 1):0]; assign dpo = ram[dpra]; always @(posedge clk) begin if (we) begin ram[a] <= di; end end endmodule