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[/] [openrisc/] [trunk/] [orpsocv2/] [bench/] [verilog/] [uart_decoder.v] - Rev 179
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////////////////////////////////////////////////////////////////////// //// //// //// ORPSoC Testbench UART Decoder //// //// //// //// Description //// //// ORPSoC Testbench UART output decoder //// //// //// //// To Do: //// //// //// //// //// //// Author(s): //// //// - jb, jb@orsoc.se //// //// //// //// //// ////////////////////////////////////////////////////////////////////// //// //// //// Copyright (C) 2009 Authors and OPENCORES.ORG //// //// //// //// 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 //// //// //// ////////////////////////////////////////////////////////////////////// // Decodes UART signals sent over the line defined by UART_TX_LINE // `include this file in the testbench and define UART_TX_LINE // Uses define CLOCK_RATE as the frequency of the clock in Hz // Receieves and decodes 8-bit, 1 stop bit, no parity UART signals. // Requires definition of: // CLK_RATE - frequency of system clock in Hz // CLK_PERIOD - period of clock frequency in ns // UART_BAUDRATE - otherwise defaults to 115200 // UART_TX_LINE - name of the UART output signal (normally a wire) // if it's not already defined, uses UART_BAUDRATE as baud to receive // bytes at `ifndef UART_BAUDRATE `define UART_BAUDRATE 115200 `endif `ifndef CLOCK_RATE initial begin $display("* WARNING: uart_decoder included but CLOCK_RATE not defined."); end `else `ifdef UART_TX_LINE parameter UART_TX_WAIT = (`CLOCK_RATE / `UART_BAUDRATE) * `CLOCK_PERIOD; // Something to trigger the task always @(posedge clk) uart_decoder; task uart_decoder; reg [7:0] tx_byte; begin while (`UART_TX_LINE !== 1'b1) @(`UART_TX_LINE); // Wait for start bit //while (`UART_TX_LINE == 1'b1) while (`UART_TX_LINE !== 1'b0) @(`UART_TX_LINE); #(UART_TX_WAIT+(UART_TX_WAIT/2)); tx_byte[0] = `UART_TX_LINE; #UART_TX_WAIT; tx_byte[1] = `UART_TX_LINE; #UART_TX_WAIT; tx_byte[2] = `UART_TX_LINE; #UART_TX_WAIT; tx_byte[3] = `UART_TX_LINE; #UART_TX_WAIT; tx_byte[4] = `UART_TX_LINE; #UART_TX_WAIT; tx_byte[5] = `UART_TX_LINE; #UART_TX_WAIT; tx_byte[6] = `UART_TX_LINE; #UART_TX_WAIT; tx_byte[7] = `UART_TX_LINE; #UART_TX_WAIT; //Check for stop bit //if (`UART_TX_LINE == 1'b0) if (`UART_TX_LINE !== 1'b1) begin //$display("* WARNING: user stop bit not received when expected at time %d__", $time); // Wait for return to idle //while (`UART_TX_LINE == 1'b0) while (`UART_TX_LINE !== 1'b1) @(`UART_TX_LINE); //$display("* USER UART returned to idle at time %d",$time); end // display the char $write("%c", tx_byte); end endtask // user_uart_read_byte `else // !`ifdef UART_TX_LINE // If this file was included but not setup properly initial begin $display("* WARNING: uart_decoder included but UART_TX_LINE not defined."); end `endif // !`ifdef UART_TX_LINE `endif // !`ifndef CLOCK_RATE
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