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[/] [usbhostslave/] [tags/] [rel_01_01/] [RTL/] [serialInterfaceEngine/] [processRxBit.v] - Blame information for rev 12

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//////////////////////////////////////////////////////////////////////
////                                                              ////
//// processrxbit
////                                                              ////
//// This file is part of the usbhostslave opencores effort.
//// http://www.opencores.org/cores/usbhostslave/                 ////
////                                                              ////
//// Module Description:                                          ////
//// 
////                                                              ////
//// To Do:                                                       ////
//// 
////                                                              ////
//// Author(s):                                                   ////
//// - Steve Fielding, sfielding@base2designs.com                 ////
////                                                              ////
//////////////////////////////////////////////////////////////////////
////                                                              ////
//// Copyright (C) 2004 Steve Fielding 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                     ////
////                                                              ////
//////////////////////////////////////////////////////////////////////
//
`timescale 1ns / 1ps
`include "usbSerialInterfaceEngine_h.v"
 
 
module processRxBit (clk, JBit, KBit, processRxBitRdy, processRxBitsWEn, processRxByteRdy, processRxByteWEn, resumeDetected, rst, RxBitsIn, RxCtrlOut, RxDataOut);
input   clk;
input   [1:0]JBit;
input   [1:0]KBit;
input   processRxBitsWEn;
input   processRxByteRdy;
input   rst;
input   [1:0]RxBitsIn;
output  processRxBitRdy;
output  processRxByteWEn;
output  resumeDetected;
output  [7:0]RxCtrlOut;
output  [7:0]RxDataOut;
 
wire    clk;
wire    [1:0]JBit;
wire    [1:0]KBit;
reg     processRxBitRdy, next_processRxBitRdy;
wire    processRxBitsWEn;
wire    processRxByteRdy;
reg     processRxByteWEn, next_processRxByteWEn;
reg     resumeDetected, next_resumeDetected;
wire    rst;
wire    [1:0]RxBitsIn;
reg     [7:0]RxCtrlOut, next_RxCtrlOut;
reg     [7:0]RxDataOut, next_RxDataOut;
 
// diagram signals declarations
reg bitStuffError, next_bitStuffError;
reg  [1:0]oldRXBits, next_oldRXBits;
reg  [3:0]resumeWaitCnt, next_resumeWaitCnt;
reg  [3:0]RXBitCount, next_RXBitCount;
reg  [1:0]RxBits, next_RxBits;
reg  [1:0]RXBitStMachCurrState, next_RXBitStMachCurrState;
reg  [7:0]RXByte, next_RXByte;
reg  [3:0]RXSameBitCount, next_RXSameBitCount;
 
// BINARY ENCODED state machine: prRxBit
// State codes definitions:
`define START 4'b0000
`define IDLE_FIRST_BIT 4'b0001
`define WAIT_BITS 4'b0010
`define IDLE_CHK_KBIT 4'b0011
`define DATA_RX_LAST_BIT 4'b0100
`define DATA_RX_CHK_SE0 4'b0101
`define DATA_RX_DATA_DESTUFF 4'b0110
`define DATA_RX_BYTE_SEND2 4'b0111
`define DATA_RX_BYTE_WAIT_RDY 4'b1000
`define RES_RX_CHK 4'b1001
`define DATA_RX_ERROR_CHK_RES 4'b1010
`define RES_END_CHK1 4'b1011
`define IDLE_WAIT_PRB_RDY 4'b1100
`define DATA_RX_WAIT_PRB_RDY 4'b1101
`define DATA_RX_ERROR_WAIT_RDY 4'b1110
 
reg [3:0]CurrState_prRxBit, NextState_prRxBit;
 
 
// Machine: prRxBit
 
// NextState logic (combinatorial)
always @ (RxBits or processRxBitsWEn or JBit or RxBitsIn or KBit or RXSameBitCount or RXBitCount or RXByte or processRxByteRdy or resumeWaitCnt or processRxByteWEn or RxCtrlOut or RxDataOut or resumeDetected or RXBitStMachCurrState or oldRXBits or bitStuffError or processRxBitRdy or CurrState_prRxBit)
begin
  NextState_prRxBit <= CurrState_prRxBit;
  // Set default values for outputs and signals
  next_processRxByteWEn <= processRxByteWEn;
  next_RxCtrlOut <= RxCtrlOut;
  next_RxDataOut <= RxDataOut;
  next_resumeDetected <= resumeDetected;
  next_RXBitStMachCurrState <= RXBitStMachCurrState;
  next_RxBits <= RxBits;
  next_RXSameBitCount <= RXSameBitCount;
  next_RXBitCount <= RXBitCount;
  next_oldRXBits <= oldRXBits;
  next_RXByte <= RXByte;
  next_bitStuffError <= bitStuffError;
  next_resumeWaitCnt <= resumeWaitCnt;
  next_processRxBitRdy <= processRxBitRdy;
  case (CurrState_prRxBit)  // synopsys parallel_case full_case
    `START:
    begin
      next_processRxByteWEn <= 1'b0;
      next_RxCtrlOut <= 8'h00;
      next_RxDataOut <= 8'h00;
      next_resumeDetected <= 1'b0;
      next_RXBitStMachCurrState <= `IDLE_BIT_ST;
      next_RxBits <= 2'b00;
      next_RXSameBitCount <= 4'h0;
      next_RXBitCount <= 4'h0;
      next_oldRXBits <= 2'b00;
      next_RXByte <= 8'h00;
      next_bitStuffError <= 1'b0;
      next_resumeWaitCnt <= 4'h0;
      next_processRxBitRdy <= 1'b1;
      NextState_prRxBit <= `WAIT_BITS;
    end
    `WAIT_BITS:
    begin
      if ((processRxBitsWEn == 1'b1) && (RXBitStMachCurrState == `DATA_RECEIVE_BIT_ST))
      begin
        NextState_prRxBit <= `DATA_RX_CHK_SE0;
        next_RxBits <= RxBitsIn;
        next_processRxBitRdy <= 1'b0;
      end
      else if ((processRxBitsWEn == 1'b1) && (RXBitStMachCurrState == `WAIT_RESUME_ST))
      begin
        NextState_prRxBit <= `RES_RX_CHK;
        next_RxBits <= RxBitsIn;
        next_processRxBitRdy <= 1'b0;
      end
      else if ((processRxBitsWEn == 1'b1) && (RXBitStMachCurrState == `RESUME_END_WAIT_ST))
      begin
        NextState_prRxBit <= `RES_END_CHK1;
        next_RxBits <= RxBitsIn;
        next_processRxBitRdy <= 1'b0;
      end
      else if ((processRxBitsWEn == 1'b1) && (RXBitStMachCurrState == `IDLE_BIT_ST))
      begin
        NextState_prRxBit <= `IDLE_CHK_KBIT;
        next_RxBits <= RxBitsIn;
        next_processRxBitRdy <= 1'b0;
      end
    end
    `IDLE_FIRST_BIT:
    begin
      next_processRxByteWEn <= 1'b0;
      next_RXBitStMachCurrState <= `DATA_RECEIVE_BIT_ST;
      next_RXSameBitCount <= 4'h0;
      next_RXBitCount <= 4'h1;
      next_oldRXBits <= RxBits;
      //zero is always the first RZ data bit of a new packet
      next_RXByte <= 8'h00;
      NextState_prRxBit <= `WAIT_BITS;
      next_processRxBitRdy <= 1'b1;
    end
    `IDLE_CHK_KBIT:
    begin
      if (RxBits == KBit)
      begin
        NextState_prRxBit <= `IDLE_WAIT_PRB_RDY;
      end
      else
      begin
        NextState_prRxBit <= `WAIT_BITS;
        next_processRxBitRdy <= 1'b1;
      end
    end
    `IDLE_WAIT_PRB_RDY:
    begin
      if (processRxByteRdy == 1'b1)
      begin
        NextState_prRxBit <= `IDLE_FIRST_BIT;
        next_RxDataOut <= 8'h00;
        //redundant data
        next_RxCtrlOut <= `DATA_START;
        //start of packet
        next_processRxByteWEn <= 1'b1;
      end
    end
    `DATA_RX_LAST_BIT:
    begin
      next_processRxByteWEn <= 1'b0;
      next_RXBitStMachCurrState <= `IDLE_BIT_ST;
      NextState_prRxBit <= `WAIT_BITS;
      next_processRxBitRdy <= 1'b1;
    end
    `DATA_RX_CHK_SE0:
    begin
      next_bitStuffError <= 1'b0;
      if (RxBits == `SE0)
      begin
        NextState_prRxBit <= `DATA_RX_WAIT_PRB_RDY;
      end
      else
      begin
        NextState_prRxBit <= `DATA_RX_DATA_DESTUFF;
        if (RxBits == oldRXBits)                 //if the current 'RxBits' are the same as the old 'RxBits', then
        begin
        next_RXSameBitCount <= RXSameBitCount + 1'b1;
        //inc 'RXSameBitCount'
        if (RXSameBitCount == `MAX_CONSEC_SAME_BITS) //if 'RXSameBitCount' == 6 there has been a bit stuff error
        next_bitStuffError <= 1'b1;
        //flag 'bitStuffError'
        else                                          //else no bit stuffing error
        begin
        next_RXBitCount <= RXBitCount + 1'b1;
        if (RXBitCount != `MAX_CONSEC_SAME_BITS_PLUS1) begin
        next_processRxBitRdy <= 1'b1;
        //early indication of ready
        end
        next_RXByte <= { 1'b1, RXByte[7:1]};
        //RZ bit <= 1 (ie no change in 'RxBits')
        end
        end
        else                                            //else current 'RxBits' are different from old 'RxBits'
        begin
        if (RXSameBitCount != `MAX_CONSEC_SAME_BITS)  //if this is not the RZ 0 bit after 6 consecutive RZ 1s, then
        begin
        next_RXBitCount <= RXBitCount + 1'b1;
        if (RXBitCount != 4'h7) begin
        next_processRxBitRdy <= 1'b1;
        //early indication of ready
        end
        next_RXByte <= {1'b0, RXByte[7:1]};
        //RZ bit <= 0 (ie current'RxBits' is different than old 'RxBits')
        end
        next_RXSameBitCount <= 4'h0;
        //reset 'RXSameBitCount'
        end
        next_oldRXBits <= RxBits;
      end
    end
    `DATA_RX_WAIT_PRB_RDY:
    begin
      if (processRxByteRdy == 1'b1)
      begin
        NextState_prRxBit <= `DATA_RX_LAST_BIT;
        next_RxDataOut <= 8'h00;
        //redundant data
        next_RxCtrlOut <= `DATA_STOP;
        //end of packet
        next_processRxByteWEn <= 1'b1;
      end
    end
    `DATA_RX_DATA_DESTUFF:
    begin
      if (RXBitCount == 4'h8 & bitStuffError == 1'b0)
      begin
        NextState_prRxBit <= `DATA_RX_BYTE_WAIT_RDY;
      end
      else if (bitStuffError == 1'b1)
      begin
        NextState_prRxBit <= `DATA_RX_ERROR_WAIT_RDY;
      end
      else
      begin
        NextState_prRxBit <= `WAIT_BITS;
        next_processRxBitRdy <= 1'b1;
      end
    end
    `DATA_RX_BYTE_SEND2:
    begin
      next_processRxByteWEn <= 1'b0;
      NextState_prRxBit <= `WAIT_BITS;
      next_processRxBitRdy <= 1'b1;
    end
    `DATA_RX_BYTE_WAIT_RDY:
    begin
      if (processRxByteRdy == 1'b1)
      begin
        NextState_prRxBit <= `DATA_RX_BYTE_SEND2;
        next_RXBitCount <= 4'h0;
        next_RxDataOut <= RXByte;
        next_RxCtrlOut <= `DATA_STREAM;
        next_processRxByteWEn <= 1'b1;
      end
    end
    `DATA_RX_ERROR_CHK_RES:
    begin
      next_processRxByteWEn <= 1'b0;
      if (RxBits == JBit)                           //if current bit is a JBit, then
      next_RXBitStMachCurrState <= `IDLE_BIT_ST;
      //next state is idle
      else                                          //else
      begin
      next_RXBitStMachCurrState <= `WAIT_RESUME_ST;
      //check for resume
      next_resumeWaitCnt <= 0;
      end
      NextState_prRxBit <= `WAIT_BITS;
      next_processRxBitRdy <= 1'b1;
    end
    `DATA_RX_ERROR_WAIT_RDY:
    begin
      if (processRxByteRdy == 1'b1)
      begin
        NextState_prRxBit <= `DATA_RX_ERROR_CHK_RES;
        next_RxDataOut <= 8'h00;
        //redundant data
        next_RxCtrlOut <= `DATA_BIT_STUFF_ERROR;
        next_processRxByteWEn <= 1'b1;
      end
    end
    `RES_RX_CHK:
    begin
      if (RxBits != KBit)  //can only be a resume if line remains in Kbit state
      next_RXBitStMachCurrState <= `IDLE_BIT_ST;
      else
      begin
      next_resumeWaitCnt <= resumeWaitCnt + 1'b1;
      //if we've waited long enough, then
      if (resumeWaitCnt == `RESUME_WAIT_TIME_MINUS1)
      begin
      next_RXBitStMachCurrState <= `RESUME_END_WAIT_ST;
      next_resumeDetected <= 1'b1;
      //report resume detected
      end
      end
      NextState_prRxBit <= `WAIT_BITS;
      next_processRxBitRdy <= 1'b1;
    end
    `RES_END_CHK1:
    begin
      if (RxBits != KBit)  //line must leave KBit state for the end of resume
      begin
      next_RXBitStMachCurrState <= `IDLE_BIT_ST;
      next_resumeDetected <= 1'b0;
      //clear resume detected flag
      end
      NextState_prRxBit <= `WAIT_BITS;
      next_processRxBitRdy <= 1'b1;
    end
  endcase
end
 
// Current State Logic (sequential)
always @ (posedge clk)
begin
  if (rst)
    CurrState_prRxBit <= `START;
  else
    CurrState_prRxBit <= NextState_prRxBit;
end
 
// Registered outputs logic
always @ (posedge clk)
begin
  if (rst)
  begin
    processRxByteWEn <= 1'b0;
    RxCtrlOut <= 8'h00;
    RxDataOut <= 8'h00;
    resumeDetected <= 1'b0;
    processRxBitRdy <= 1'b1;
    RXBitStMachCurrState <= `IDLE_BIT_ST;
    RxBits <= 2'b00;
    RXSameBitCount <= 4'h0;
    RXBitCount <= 4'h0;
    oldRXBits <= 2'b00;
    RXByte <= 8'h00;
    bitStuffError <= 1'b0;
    resumeWaitCnt <= 4'h0;
  end
  else
  begin
    processRxByteWEn <= next_processRxByteWEn;
    RxCtrlOut <= next_RxCtrlOut;
    RxDataOut <= next_RxDataOut;
    resumeDetected <= next_resumeDetected;
    processRxBitRdy <= next_processRxBitRdy;
    RXBitStMachCurrState <= next_RXBitStMachCurrState;
    RxBits <= next_RxBits;
    RXSameBitCount <= next_RXSameBitCount;
    RXBitCount <= next_RXBitCount;
    oldRXBits <= next_oldRXBits;
    RXByte <= next_RXByte;
    bitStuffError <= next_bitStuffError;
    resumeWaitCnt <= next_resumeWaitCnt;
  end
end
 
endmodule

Line No.	Rev	Author	Line
1	5	sfielding
2			`//////////////////////////////////////////////////////////////////////`
3			`//// ////`
4			`//// processrxbit`
5			`//// ////`
6			`//// This file is part of the usbhostslave opencores effort.`
7			`//// http://www.opencores.org/cores/usbhostslave/ ////`
8			`//// ////`
9			`//// Module Description: ////`
10			`////`
11			`//// ////`
12			`//// To Do: ////`
13			`////`
14			`//// ////`
15			`//// Author(s): ////`
16			`//// - Steve Fielding, sfielding@base2designs.com ////`
17			`//// ////`
18			`//////////////////////////////////////////////////////////////////////`
19			`//// ////`
20			`//// Copyright (C) 2004 Steve Fielding and OPENCORES.ORG ////`
21			`//// ////`
22			`//// This source file may be used and distributed without ////`
23			`//// restriction provided that this copyright statement is not ////`
24			`//// removed from the file and that any derivative work contains ////`
25			`//// the original copyright notice and the associated disclaimer. ////`
26			`//// ////`
27			`//// This source file is free software; you can redistribute it ////`
28			`//// and/or modify it under the terms of the GNU Lesser General ////`
29			`//// Public License as published by the Free Software Foundation; ////`
30			`//// either version 2.1 of the License, or (at your option) any ////`
31			`//// later version. ////`
32			`//// ////`
33			`//// This source is distributed in the hope that it will be ////`
34			`//// useful, but WITHOUT ANY WARRANTY; without even the implied ////`
35			`//// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR ////`
36			`//// PURPOSE. See the GNU Lesser General Public License for more ////`
37			`//// details. ////`
38			`//// ////`
39			`//// You should have received a copy of the GNU Lesser General ////`
40			`//// Public License along with this source; if not, download it ////`
41			`//// from http://www.opencores.org/lgpl.shtml ////`
42			`//// ////`
43			`//////////////////////////////////////////////////////////////////////`
44			`//`
45			`timescale 1ns / 1ps
46			`include "usbSerialInterfaceEngine_h.v"
47
48
49			`module processRxBit (clk, JBit, KBit, processRxBitRdy, processRxBitsWEn, processRxByteRdy, processRxByteWEn, resumeDetected, rst, RxBitsIn, RxCtrlOut, RxDataOut);`
50			`input clk;`
51			`input [1:0]JBit;`
52			`input [1:0]KBit;`
53			`input processRxBitsWEn;`
54			`input processRxByteRdy;`
55			`input rst;`
56			`input [1:0]RxBitsIn;`
57			`output processRxBitRdy;`
58			`output processRxByteWEn;`
59			`output resumeDetected;`
60			`output [7:0]RxCtrlOut;`
61			`output [7:0]RxDataOut;`
62
63			`wire clk;`
64			`wire [1:0]JBit;`
65			`wire [1:0]KBit;`
66			`reg processRxBitRdy, next_processRxBitRdy;`
67			`wire processRxBitsWEn;`
68			`wire processRxByteRdy;`
69			`reg processRxByteWEn, next_processRxByteWEn;`
70			`reg resumeDetected, next_resumeDetected;`
71			`wire rst;`
72			`wire [1:0]RxBitsIn;`
73			`reg [7:0]RxCtrlOut, next_RxCtrlOut;`
74			`reg [7:0]RxDataOut, next_RxDataOut;`
75
76			`// diagram signals declarations`
77			`reg bitStuffError, next_bitStuffError;`
78			`reg [1:0]oldRXBits, next_oldRXBits;`
79			`reg [3:0]resumeWaitCnt, next_resumeWaitCnt;`
80			`reg [3:0]RXBitCount, next_RXBitCount;`
81			`reg [1:0]RxBits, next_RxBits;`
82			`reg [1:0]RXBitStMachCurrState, next_RXBitStMachCurrState;`
83			`reg [7:0]RXByte, next_RXByte;`
84			`reg [3:0]RXSameBitCount, next_RXSameBitCount;`
85
86			`// BINARY ENCODED state machine: prRxBit`
87			`// State codes definitions:`
88			`define START 4'b0000
89			`define IDLE_FIRST_BIT 4'b0001
90			`define WAIT_BITS 4'b0010
91			`define IDLE_CHK_KBIT 4'b0011
92			`define DATA_RX_LAST_BIT 4'b0100
93			`define DATA_RX_CHK_SE0 4'b0101
94			`define DATA_RX_DATA_DESTUFF 4'b0110
95			`define DATA_RX_BYTE_SEND2 4'b0111
96			`define DATA_RX_BYTE_WAIT_RDY 4'b1000
97			`define RES_RX_CHK 4'b1001
98			`define DATA_RX_ERROR_CHK_RES 4'b1010
99			`define RES_END_CHK1 4'b1011
100			`define IDLE_WAIT_PRB_RDY 4'b1100
101			`define DATA_RX_WAIT_PRB_RDY 4'b1101
102			`define DATA_RX_ERROR_WAIT_RDY 4'b1110
103
104			`reg [3:0]CurrState_prRxBit, NextState_prRxBit;`
105
106
107			`// Machine: prRxBit`
108
109			`// NextState logic (combinatorial)`
110			`always @ (RxBits or processRxBitsWEn or JBit or RxBitsIn or KBit or RXSameBitCount or RXBitCount or RXByte or processRxByteRdy or resumeWaitCnt or processRxByteWEn or RxCtrlOut or RxDataOut or resumeDetected or RXBitStMachCurrState or oldRXBits or bitStuffError or processRxBitRdy or CurrState_prRxBit)`
111			`begin`
112			`NextState_prRxBit <= CurrState_prRxBit;`
113			`// Set default values for outputs and signals`
114			`next_processRxByteWEn <= processRxByteWEn;`
115			`next_RxCtrlOut <= RxCtrlOut;`
116			`next_RxDataOut <= RxDataOut;`
117			`next_resumeDetected <= resumeDetected;`
118			`next_RXBitStMachCurrState <= RXBitStMachCurrState;`
119			`next_RxBits <= RxBits;`
120			`next_RXSameBitCount <= RXSameBitCount;`
121			`next_RXBitCount <= RXBitCount;`
122			`next_oldRXBits <= oldRXBits;`
123			`next_RXByte <= RXByte;`
124			`next_bitStuffError <= bitStuffError;`
125			`next_resumeWaitCnt <= resumeWaitCnt;`
126			`next_processRxBitRdy <= processRxBitRdy;`
127			`case (CurrState_prRxBit) // synopsys parallel_case full_case`
128			`START:
129			`begin`
130			`next_processRxByteWEn <= 1'b0;`
131			`next_RxCtrlOut <= 8'h00;`
132			`next_RxDataOut <= 8'h00;`
133			`next_resumeDetected <= 1'b0;`
134			next_RXBitStMachCurrState <= `IDLE_BIT_ST;
135			`next_RxBits <= 2'b00;`
136			`next_RXSameBitCount <= 4'h0;`
137			`next_RXBitCount <= 4'h0;`
138			`next_oldRXBits <= 2'b00;`
139			`next_RXByte <= 8'h00;`
140			`next_bitStuffError <= 1'b0;`
141			`next_resumeWaitCnt <= 4'h0;`
142			`next_processRxBitRdy <= 1'b1;`
143			NextState_prRxBit <= `WAIT_BITS;
144			`end`
145			`WAIT_BITS:
146			`begin`
147	12	sfielding	if ((processRxBitsWEn == 1'b1) && (RXBitStMachCurrState == `DATA_RECEIVE_BIT_ST))
148	5	sfielding	`begin`
149	12	sfielding	NextState_prRxBit <= `DATA_RX_CHK_SE0;
150	5	sfielding	`next_RxBits <= RxBitsIn;`
151			`next_processRxBitRdy <= 1'b0;`
152			`end`
153	12	sfielding	else if ((processRxBitsWEn == 1'b1) && (RXBitStMachCurrState == `WAIT_RESUME_ST))
154	5	sfielding	`begin`
155	12	sfielding	NextState_prRxBit <= `RES_RX_CHK;
156	5	sfielding	`next_RxBits <= RxBitsIn;`
157			`next_processRxBitRdy <= 1'b0;`
158			`end`
159	12	sfielding	else if ((processRxBitsWEn == 1'b1) && (RXBitStMachCurrState == `RESUME_END_WAIT_ST))
160	5	sfielding	`begin`
161	12	sfielding	NextState_prRxBit <= `RES_END_CHK1;
162	5	sfielding	`next_RxBits <= RxBitsIn;`
163			`next_processRxBitRdy <= 1'b0;`
164			`end`
165	12	sfielding	else if ((processRxBitsWEn == 1'b1) && (RXBitStMachCurrState == `IDLE_BIT_ST))
166	5	sfielding	`begin`
167	12	sfielding	NextState_prRxBit <= `IDLE_CHK_KBIT;
168	5	sfielding	`next_RxBits <= RxBitsIn;`
169			`next_processRxBitRdy <= 1'b0;`
170			`end`
171			`end`
172			`IDLE_FIRST_BIT:
173			`begin`
174			`next_processRxByteWEn <= 1'b0;`
175			next_RXBitStMachCurrState <= `DATA_RECEIVE_BIT_ST;
176	12	sfielding	`next_RXSameBitCount <= 4'h0;`
177	5	sfielding	`next_RXBitCount <= 4'h1;`
178			`next_oldRXBits <= RxBits;`
179			`//zero is always the first RZ data bit of a new packet`
180			`next_RXByte <= 8'h00;`
181			NextState_prRxBit <= `WAIT_BITS;
182			`next_processRxBitRdy <= 1'b1;`
183			`end`
184			`IDLE_CHK_KBIT:
185			`begin`
186			`if (RxBits == KBit)`
187			`begin`
188			NextState_prRxBit <= `IDLE_WAIT_PRB_RDY;
189			`end`
190			`else`
191			`begin`
192			NextState_prRxBit <= `WAIT_BITS;
193			`next_processRxBitRdy <= 1'b1;`
194			`end`
195			`end`
196			`IDLE_WAIT_PRB_RDY:
197			`begin`
198			`if (processRxByteRdy == 1'b1)`
199			`begin`
200			NextState_prRxBit <= `IDLE_FIRST_BIT;
201			`next_RxDataOut <= 8'h00;`
202			`//redundant data`
203			next_RxCtrlOut <= `DATA_START;
204			`//start of packet`
205			`next_processRxByteWEn <= 1'b1;`
206			`end`
207			`end`
208			`DATA_RX_LAST_BIT:
209			`begin`
210			`next_processRxByteWEn <= 1'b0;`
211			next_RXBitStMachCurrState <= `IDLE_BIT_ST;
212			NextState_prRxBit <= `WAIT_BITS;
213			`next_processRxBitRdy <= 1'b1;`
214			`end`
215			`DATA_RX_CHK_SE0:
216			`begin`
217			`next_bitStuffError <= 1'b0;`
218			if (RxBits == `SE0)
219			`begin`
220			NextState_prRxBit <= `DATA_RX_WAIT_PRB_RDY;
221			`end`
222			`else`
223			`begin`
224			NextState_prRxBit <= `DATA_RX_DATA_DESTUFF;
225			`if (RxBits == oldRXBits) //if the current 'RxBits' are the same as the old 'RxBits', then`
226			`begin`
227			`next_RXSameBitCount <= RXSameBitCount + 1'b1;`
228			`//inc 'RXSameBitCount'`
229	12	sfielding	if (RXSameBitCount == `MAX_CONSEC_SAME_BITS) //if 'RXSameBitCount' == 6 there has been a bit stuff error
230	5	sfielding	`next_bitStuffError <= 1'b1;`
231			`//flag 'bitStuffError'`
232			`else //else no bit stuffing error`
233			`begin`
234			`next_RXBitCount <= RXBitCount + 1'b1;`
235	12	sfielding	if (RXBitCount != `MAX_CONSEC_SAME_BITS_PLUS1) begin
236	5	sfielding	`next_processRxBitRdy <= 1'b1;`
237			`//early indication of ready`
238			`end`
239			`next_RXByte <= { 1'b1, RXByte[7:1]};`
240			`//RZ bit <= 1 (ie no change in 'RxBits')`
241			`end`
242			`end`
243			`else //else current 'RxBits' are different from old 'RxBits'`
244			`begin`
245			if (RXSameBitCount != `MAX_CONSEC_SAME_BITS) //if this is not the RZ 0 bit after 6 consecutive RZ 1s, then
246			`begin`
247			`next_RXBitCount <= RXBitCount + 1'b1;`
248			`if (RXBitCount != 4'h7) begin`
249			`next_processRxBitRdy <= 1'b1;`
250			`//early indication of ready`
251			`end`
252			`next_RXByte <= {1'b0, RXByte[7:1]};`
253			`//RZ bit <= 0 (ie current'RxBits' is different than old 'RxBits')`
254			`end`
255	12	sfielding	`next_RXSameBitCount <= 4'h0;`
256	5	sfielding	`//reset 'RXSameBitCount'`
257			`end`
258			`next_oldRXBits <= RxBits;`
259			`end`
260			`end`
261			`DATA_RX_WAIT_PRB_RDY:
262			`begin`
263			`if (processRxByteRdy == 1'b1)`
264			`begin`
265			NextState_prRxBit <= `DATA_RX_LAST_BIT;
266			`next_RxDataOut <= 8'h00;`
267			`//redundant data`
268			next_RxCtrlOut <= `DATA_STOP;
269			`//end of packet`
270			`next_processRxByteWEn <= 1'b1;`
271			`end`
272			`end`
273			`DATA_RX_DATA_DESTUFF:
274			`begin`
275			`if (RXBitCount == 4'h8 & bitStuffError == 1'b0)`
276			`begin`
277			NextState_prRxBit <= `DATA_RX_BYTE_WAIT_RDY;
278			`end`
279			`else if (bitStuffError == 1'b1)`
280			`begin`
281			NextState_prRxBit <= `DATA_RX_ERROR_WAIT_RDY;
282			`end`
283			`else`
284			`begin`
285			NextState_prRxBit <= `WAIT_BITS;
286			`next_processRxBitRdy <= 1'b1;`
287			`end`
288			`end`
289			`DATA_RX_BYTE_SEND2:
290			`begin`
291			`next_processRxByteWEn <= 1'b0;`
292			NextState_prRxBit <= `WAIT_BITS;
293			`next_processRxBitRdy <= 1'b1;`
294			`end`
295			`DATA_RX_BYTE_WAIT_RDY:
296			`begin`
297			`if (processRxByteRdy == 1'b1)`
298			`begin`
299			NextState_prRxBit <= `DATA_RX_BYTE_SEND2;
300			`next_RXBitCount <= 4'h0;`
301			`next_RxDataOut <= RXByte;`
302			next_RxCtrlOut <= `DATA_STREAM;
303			`next_processRxByteWEn <= 1'b1;`
304			`end`
305			`end`
306			`DATA_RX_ERROR_CHK_RES:
307			`begin`
308			`next_processRxByteWEn <= 1'b0;`
309			`if (RxBits == JBit) //if current bit is a JBit, then`
310			next_RXBitStMachCurrState <= `IDLE_BIT_ST;
311			`//next state is idle`
312			`else //else`
313			`begin`
314			next_RXBitStMachCurrState <= `WAIT_RESUME_ST;
315			`//check for resume`
316			`next_resumeWaitCnt <= 0;`
317			`end`
318			NextState_prRxBit <= `WAIT_BITS;
319			`next_processRxBitRdy <= 1'b1;`
320			`end`
321			`DATA_RX_ERROR_WAIT_RDY:
322			`begin`
323			`if (processRxByteRdy == 1'b1)`
324			`begin`
325			NextState_prRxBit <= `DATA_RX_ERROR_CHK_RES;
326			`next_RxDataOut <= 8'h00;`
327			`//redundant data`
328			next_RxCtrlOut <= `DATA_BIT_STUFF_ERROR;
329			`next_processRxByteWEn <= 1'b1;`
330			`end`
331			`end`
332			`RES_RX_CHK:
333			`begin`
334			`if (RxBits != KBit) //can only be a resume if line remains in Kbit state`
335			next_RXBitStMachCurrState <= `IDLE_BIT_ST;
336			`else`
337			`begin`
338			`next_resumeWaitCnt <= resumeWaitCnt + 1'b1;`
339			`//if we've waited long enough, then`
340			if (resumeWaitCnt == `RESUME_WAIT_TIME_MINUS1)
341			`begin`
342			next_RXBitStMachCurrState <= `RESUME_END_WAIT_ST;
343			`next_resumeDetected <= 1'b1;`
344			`//report resume detected`
345			`end`
346			`end`
347			NextState_prRxBit <= `WAIT_BITS;
348			`next_processRxBitRdy <= 1'b1;`
349			`end`
350			`RES_END_CHK1:
351			`begin`
352			`if (RxBits != KBit) //line must leave KBit state for the end of resume`
353			`begin`
354			next_RXBitStMachCurrState <= `IDLE_BIT_ST;
355			`next_resumeDetected <= 1'b0;`
356			`//clear resume detected flag`
357			`end`
358			NextState_prRxBit <= `WAIT_BITS;
359			`next_processRxBitRdy <= 1'b1;`
360			`end`
361			`endcase`
362			`end`
363
364			`// Current State Logic (sequential)`
365			`always @ (posedge clk)`
366			`begin`
367			`if (rst)`
368			CurrState_prRxBit <= `START;
369			`else`
370			`CurrState_prRxBit <= NextState_prRxBit;`
371			`end`
372
373			`// Registered outputs logic`
374			`always @ (posedge clk)`
375			`begin`
376			`if (rst)`
377			`begin`
378			`processRxByteWEn <= 1'b0;`
379			`RxCtrlOut <= 8'h00;`
380			`RxDataOut <= 8'h00;`
381			`resumeDetected <= 1'b0;`
382			`processRxBitRdy <= 1'b1;`
383			RXBitStMachCurrState <= `IDLE_BIT_ST;
384			`RxBits <= 2'b00;`
385			`RXSameBitCount <= 4'h0;`
386			`RXBitCount <= 4'h0;`
387			`oldRXBits <= 2'b00;`
388			`RXByte <= 8'h00;`
389			`bitStuffError <= 1'b0;`
390			`resumeWaitCnt <= 4'h0;`
391			`end`
392			`else`
393			`begin`
394			`processRxByteWEn <= next_processRxByteWEn;`
395			`RxCtrlOut <= next_RxCtrlOut;`
396			`RxDataOut <= next_RxDataOut;`
397			`resumeDetected <= next_resumeDetected;`
398			`processRxBitRdy <= next_processRxBitRdy;`
399			`RXBitStMachCurrState <= next_RXBitStMachCurrState;`
400			`RxBits <= next_RxBits;`
401			`RXSameBitCount <= next_RXSameBitCount;`
402			`RXBitCount <= next_RXBitCount;`
403			`oldRXBits <= next_oldRXBits;`
404			`RXByte <= next_RXByte;`
405			`bitStuffError <= next_bitStuffError;`
406			`resumeWaitCnt <= next_resumeWaitCnt;`
407			`end`
408			`end`
409
410	2	sfielding	`endmodule`

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