//////////////////////////////////////////////////////////////////////////////////////////////////----------------------------------------------------------------------//// Copyright (c) 2002-2003 CAST, inc.//// Please review the terms of the license agreement before using this// file.  If you are not an authorized user, please destroy this source// code file and notify CAST immediately that you inadvertently received// an unauthorized copy.//----------------------------------------------------------------------////  Project       : H16550 UART////  File          : h16550tb4.vhd////  Dependencies  : h16550w.vhd////  Model Type    : Simulation Model (Testbench)////  Description   : H16550 testbench 4////  Designer      : JV////  QA Engineer   : Joram Heilbronner////  Creation Date : 13-January-2002////  Last Update   : 15-February-2002////  Version       : 2.0V////  History       : 1.1 - 02/18/02    VHDL Release////  Tested Operations:  REGISTERS; write and READ  //                      TRANSMISSION; different modes can be changed by modify initial constant \"initLCR\"//                      RECEIVING//                      outputS DTR, RTS, OUT1 and OUT2//                      INPUTS CTS, DSR, DCD and SIN; and effects to Modem Status Register//                      INTERRUPTS//                      BAUDOUT; values of the Divisor registers can be changed////   The main idea of testbench is to write values to registers and check interrupts,//   status ot the UART and outputs several times//   //   The UART is tested in several combinations//   Different values of data and stop bits and parity operations are tested//   All cases are descripted in next table//  // CASE 1:   7 data bits, no parity, 1 stop bit             =>  LCReg = \"00110010\"// CASE 2:   7 data bits, stick parity '1', 2 stop bits     =>  LCReg = \"00101110\"// CASE 3:   7 data bits, stick parity '0', 1 stop bit      =>  LCReg = \"00111010\"// CASE 4:   7 data bits, even parity, 2 stop bits          =>  LCReg = \"00011110\"// CASE 5:   5 data bits, no parity, 1.5 stop bits          =>  LCReg = \"00010100\"// CASE 6:   5 data bits, stick parity '1', 1 stop bit      =>  LCReg = \"00101000\"// CASE 7:   5 data bits, stick parity '0', 1 stop bit      =>  LCReg = \"00111000\"// CASE 8:   5 data bits, odd parity, 1.5 stop bits         =>  LCReg = \"00001100\"// CASE 9:   6 data bits, no parity, 1 stop bit             =>  LCReg = \"00100001\"// CASE 10:  6 data bits, stick parity '1', 2 stop bits     =>  LCReg = \"00101101\"// CASE 11:  6 data bits, stick parity '0', 2 stop bits     =>  LCReg = \"00111101\"// CASE 12:  6 data bits, even parity, 1 stop bit           =>  LCReg = \"00011001\"// CASE 13:  8 data bits, no parity, 1 stop bit             =>  LCReg = \"00000011\"// CASE 14:  8 data bits, stick parity '1', 1 stop bit      =>  LCReg = \"00101011\"// CASE 15:  8 data bits, stick parity '0', 2 stop bits     =>  LCReg = \"00111111\"// CASE 16:  8 data bits, odd parity, 2 stop bits           =>  LCReg = \"00001111\"////   Run for 1100 us//----------------------------------------------------------------------`timescale 1 ns/1 psmodule h16550tb ();   parameter scale  = 1.0;   reg test_done;    integer errors;    reg mr;    reg[2:0] a;    reg ads;    reg cs;    reg wr;    reg rd;    reg clk;    reg rclk;    reg sin;    reg cts;    reg dsr;    reg dcd;    reg ri;    wire ddis;    wire baudout;    wire sout;    wire rxrdyn;    wire txrdyn;    wire rts;    wire dtr;    wire out1;    wire out2;    wire intr;    wire[7:0] dout;    reg[7:0] data;    reg[7:0] din;    parameter period = 100 * scale;    parameter cpu_tpd = period / 3;    parameter cpu_trdwr = cpu_tpd / 2;    reg debug; // Used for regression testing   // CONSTANTs to write to registers   // The value of the Line Control Register constant can be changed to appropriate operation mode   // The values of the Divisor registers can be changed to modify data speed   reg[7:0] initlcr;    parameter[7:0] initmcr = 8'b00000101;    parameter[7:0] initier = 8'b00001111;    parameter[7:0] initsr = 8'b11011111;    parameter[7:0] initdlr = 8'b00000010;    parameter[7:0] initdmr = 8'b00000000;    reg[7:0] initthr;    // ADDRESSES of the registers   // THESE values can not be changed   parameter[2:0] rbradd = 3'b000;    parameter[2:0] thradd = 3'b000;    parameter[2:0] dlradd = 3'b000;    parameter[2:0] dmradd = 3'b001;    parameter[2:0] ieradd = 3'b001;    parameter[2:0] iiradd = 3'b010;    parameter[2:0] lcradd = 3'b011;    parameter[2:0] mcradd = 3'b100;    parameter[2:0] lsradd = 3'b101;    parameter[2:0] msradd = 3'b110;    parameter[2:0] sradd = 3'b111;    reg gnd;    reg vcc;    reg do_reset;    task wait_n_cycle;      input ncycle;      integer ncycle;      begin         begin : xhdl_8            integer i;            for(i = ncycle; i >= 0; i = i - 1)            begin               @(posedge clk);            end         end      end   endtask   task cpu_write;      input[7:0] data;      input[2:0] reg_addr;      input dlab;          begin         @(posedge clk);         #cpu_tpd;         a <= reg_addr ;         cs <= 1'b1 ;         din <= data ;         #cpu_trdwr;         wr <= 1'b1 ;         @(posedge clk);         #cpu_tpd;         wr <= 1'b0 ;         #cpu_trdwr;         cs <= 1'b0 ;         din <= 8'bZZZZZZZZ ;         $write($stime,,"ns MPU Write: Register");         case (reg_addr)            3'b000 :                     begin                        if (dlab)                        begin                           $write(" DLR");                        end                          else                        begin                           $write(" THR");                        end                       end            3'b001 :                     begin                        if (dlab)                        begin                           $write(" DMR");                        end                          else                        begin                           $write(" IER");                        end                       end            3'b010 :                     begin                        $write(" FCR ");                     end              3'b011 :                     begin                        $write(" LCR ");                     end            3'b100 :                     begin                        $write(" MCR ");                     end            3'b101 :                     begin                        $write(" LSR ");                     end            3'b110 :                     begin                        $write(" MSR ");                     end            3'b111 :                     begin                        $write(" SCR ");                     end            default :                     begin                        $write(" Unknown ");                     end         endcase         $display("= %b", data);      end   endtask   task cpu_read;      input[2:0] reg_addr;      input[7:0] ref;      input dlab;      input check;      begin         @(posedge clk);         #cpu_tpd;         a <= reg_addr ;         cs <= 1'b1 ;         #cpu_trdwr;         rd <= 1'b1 ;         @(posedge clk);         #cpu_tpd;         rd <= 1'b0 ;         $write($stime,,"ns  MPU Read: Register");         case (reg_addr)            3'b000 :                     begin                        if (dlab)                        begin                           $write(" DLR");                        end                        else                        begin                           $write(" RBR");                        end                     end            3'b001 :                     begin                        if (dlab)                        begin                           $write(" DMR");                        end                        else                        begin                           $write(" IER");                        end                     end            3'b010 :                     begin                        $write(" ISR ");                     end            3'b011 :                     begin                        $write(" LCR ");                     end            3'b100 :                     begin                        $write(" MCR ");                     end            3'b101 :                     begin                        $write(" LSR ");                     end            3'b110 :                     begin                        $write(" MSR ");                     end            3'b111 :                     begin                        $write(" SCR ");                     end            default :                     begin                        $write(" Unknown ");                     end         endcase         if (check)         begin            $write("= %b", dout);         end         else         begin            $display("= %b", dout);         end         if (check)         begin            if (dout != ref)            begin               $write(" ##### NOK");               $write(" EXPECTED RESULT IS  ");               $display(" %b  #####", ref);               errors <= errors + 1 ;            end            else            begin               $display("  OK");            end         end         #cpu_trdwr;         cs <= 1'b0 ;         @(posedge clk);         #cpu_tpd;      end   endtask   initial   begin      test_done <= 1'b0;      errors <= 0;      mr <= 1'b1;      a <= 3'b000 ;      ads <= 1'b1;      cs <= 1'b0;      wr <= 1'b0;      rd <= 1'b0;      clk <= 1'b0;      rclk <= 1'b0;      sin <= 1'b0;      cts <= 1'b1;      dsr <= 1'b1;      dcd <= 1'b1;      ri <= 1'b1;      din <= 8'b00000000 ;      debug <= 1'b0;      initlcr <= 8'b00110010;      initthr <= 8'b01010110;      gnd <= 1'b0;      vcc <= 1'b1;      do_reset <= 1'b0;   end   h16550w u1 (.a(a), .adsn(ads), .cs0(cs), .cs1(vcc), .cs2n(gnd), .wr(wr),   .rd(rd), .mr(mr), .clk(clk), .rclk(rclk), .sin(sin), .ctsn(cts), .dsrn(dsr), .dcdn(dcd),   .rin(ri), .ddis(ddis), .baudoutn(baudout), .sout(sout), .rtsn(rts), .dtrn(dtr),   .out1n(out1), .out2n(out2), .intr(intr), .rxrdyn(rxrdyn), .txrdyn(txrdyn),   .dout(dout[7:0]), .din(din[7:0]));    //-------------------------------------------------   // Infinite clock generator   //-------------------------------------------------   always @(baudout)   begin       rclk <= baudout ;   end   always @(sout)   begin      sin <= sout ;   end   //-------------------------------------------------   // Asynchronous reset   //-------------------------------------------------   always    begin      #50;       mr <= 1'b1 ;       #230;       mr <= 1'b0 ;       @(posedge do_reset);       mr <= 1'b1 ;       #200;       mr <= 1'b0 ;       forever #100000;    end    always    begin : clk_stim      forever      begin         #(period / 2);          clk <= ~clk ;          if (test_done)         begin            clk <= ~clk ;            $display("TEST COMPLETE");            if (errors == 0)            begin               $display("There were no errors");