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//////////////////////////////////////////////////////////////////////

////                                                              ////

////  can_bsp.v                                                   ////

////                                                              ////

////                                                              ////

////  This file is part of the CAN Protocol Controller            ////

////  http://www.opencores.org/projects/can/                      ////

////                                                              ////

////                                                              ////

////  Author(s):                                                  ////

////       Igor Mohor                                             ////

////       igorm@opencores.org                                    ////

////                                                              ////

////                                                              ////

////  All additional information is available in the README.txt   ////

////  file.                                                       ////

////                                                              ////

//////////////////////////////////////////////////////////////////////

////                                                              ////

//// Copyright (C) 2002, 2003 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: not supported by cvs2svn $

// Revision 1.15  2003/01/31 01:13:37  mohor

// backup.

//

// Revision 1.14  2003/01/16 13:36:19  mohor

// Form error supported. When receiving messages, last bit of the end-of-frame

// does not generate form error. Receiver goes to the idle mode one bit sooner.

// (CAN specification ver 2.0, part B, page 57).

//

// Revision 1.13  2003/01/15 21:59:45  mohor

// Data is stored to fifo at the end of ack stage.

//

// Revision 1.12  2003/01/15 21:05:11  mohor

// CRC checking fixed (when bitstuff occurs at the end of a CRC sequence).

//

// Revision 1.11  2003/01/15 14:40:23  mohor

// RX state machine fixed to receive "remote request" frames correctly. No data bytes are written to fifo when such frames are received.

//

// Revision 1.10  2003/01/15 13:16:47  mohor

// When a frame with "remote request" is received, no data is stored to fifo, just the frame information (identifier, ...). Data length that is stored is the received data length and not the actual data length that is stored to fifo.

//

// Revision 1.9  2003/01/14 12:19:35  mohor

// rx_fifo is now working.

//

// Revision 1.8  2003/01/10 17:51:33  mohor

// Temporary version (backup).

//

// Revision 1.7  2003/01/09 21:54:45  mohor

// rx fifo added. Not 100 % verified, yet.

//

// Revision 1.6  2003/01/09 14:46:58  mohor

// Temporary files (backup).

//

// Revision 1.5  2003/01/08 13:30:31  mohor

// Temp version.

//

// Revision 1.4  2003/01/08 02:10:53  mohor

// Acceptance filter added.

//

// Revision 1.3  2002/12/28 04:13:23  mohor

// Backup version.

//

// Revision 1.2  2002/12/27 00:12:52  mohor

// Header changed, testbench improved to send a frame (crc still missing).

//

// Revision 1.1.1.1  2002/12/20 16:39:21  mohor

// Initial

//

//

//

// synopsys translate_off

`include "timescale.v"

// synopsys translate_on

`include "can_defines.v"

module can_bsp

(

  clk,

  rst,

  sample_point,

  sampled_bit,

  sampled_bit_q,

  tx_point,

  hard_sync,

  addr,

  data_out,

  /* Mode register */

  reset_mode,

  acceptance_filter_mode,

  /* Command register */

  release_buffer,

  tx_request,

  /* Clock Divider register */

  extended_mode,

  rx_idle,

  transmitting,

  /* This section is for BASIC and EXTENDED mode */

  /* Acceptance code register */

  acceptance_code_0,

  /* Acceptance mask register */

  acceptance_mask_0,

  /* End: This section is for BASIC and EXTENDED mode */

  /* This section is for EXTENDED mode */

  /* Acceptance code register */

  acceptance_code_1,

  acceptance_code_2,

  acceptance_code_3,

  /* Acceptance mask register */

  acceptance_mask_1,

  acceptance_mask_2,

  acceptance_mask_3,

  /* End: This section is for EXTENDED mode */

  /* Tx data registers. Holding identifier (basic mode), tx frame information (extended mode) and data */

  tx_data_0,

  tx_data_1,

  tx_data_2,

  tx_data_3,

  tx_data_4,

  tx_data_5,

  tx_data_6,

  tx_data_7,

  tx_data_8,

  tx_data_9,

  tx_data_10,

  tx_data_11,

  tx_data_12,

  /* End: Tx data registers */

  /* Tx signal */

  tx

);

parameter Tp = 1;

input         clk;

input         rst;

input         sample_point;

input         sampled_bit;

input         sampled_bit_q;

input         tx_point;

input         hard_sync;

input   [7:0] addr;

output  [7:0] data_out;

input         reset_mode;

input         acceptance_filter_mode;

input         extended_mode;

/* Command register */

input         release_buffer;

input         tx_request;

output        rx_idle;

output        transmitting;

/* This section is for BASIC and EXTENDED mode */

/* Acceptance code register */

input   [7:0] acceptance_code_0;

/* Acceptance mask register */

input   [7:0] acceptance_mask_0;

/* End: This section is for BASIC and EXTENDED mode */

/* This section is for EXTENDED mode */

/* Acceptance code register */

input   [7:0] acceptance_code_1;

input   [7:0] acceptance_code_2;

input   [7:0] acceptance_code_3;

/* Acceptance mask register */

input   [7:0] acceptance_mask_1;

input   [7:0] acceptance_mask_2;

input   [7:0] acceptance_mask_3;

/* End: This section is for EXTENDED mode */

/* Tx data registers. Holding identifier (basic mode), tx frame information (extended mode) and data */

input   [7:0] tx_data_0;

input   [7:0] tx_data_1;

input   [7:0] tx_data_2;

input   [7:0] tx_data_3;

input   [7:0] tx_data_4;

input   [7:0] tx_data_5;

input   [7:0] tx_data_6;

input   [7:0] tx_data_7;

input   [7:0] tx_data_8;

input   [7:0] tx_data_9;

input   [7:0] tx_data_10;

input   [7:0] tx_data_11;

input   [7:0] tx_data_12;

/* End: Tx data registers */

/* Tx signal */

output        tx;

reg           reset_mode_q;

reg     [5:0] bit_cnt;

reg     [3:0] data_len;

reg    [28:0] id;

reg     [2:0] bit_stuff_cnt;

reg     [2:0] bit_stuff_cnt_tx;

reg           stuff_error;

reg           tx_point_q;

wire          bit_de_stuff;

wire          bit_de_stuff_tx;

/* Rx state machine */

wire          go_rx_idle;

wire          go_rx_id1;

wire          go_rx_rtr1;

wire          go_rx_ide;

wire          go_rx_id2;

wire          go_rx_rtr2;

wire          go_rx_r1;

wire          go_rx_r0;

wire          go_rx_dlc;

wire          go_rx_data;

wire          go_rx_crc;

wire          go_rx_crc_lim;

wire          go_rx_ack;

wire          go_rx_ack_lim;

wire          go_rx_eof;

wire          go_error_frame;

wire          go_overload_frame;

wire          go_rx_inter;

wire          go_crc_enable;

wire          rst_crc_enable;

wire          bit_de_stuff_set;

wire          bit_de_stuff_reset;

wire          go_early_tx;

wire          go_tx;

reg           rx_idle;

reg           rx_id1;

reg           rx_rtr1;

reg           rx_ide;

reg           rx_id2;

reg           rx_rtr2;

reg           rx_r1;

reg           rx_r0;

reg           rx_dlc;

reg           rx_data;

reg           rx_crc;

reg           rx_crc_lim;

reg           rx_ack;

reg           rx_ack_lim;

reg           rx_eof;

reg           rx_inter;

reg           rtr1;

reg           ide;

reg           rtr2;

reg    [14:0] crc_in;

reg     [7:0] tmp_data;

reg     [7:0] tmp_fifo [0:7];

reg           write_data_to_tmp_fifo;

reg     [2:0] byte_cnt;

reg           bit_stuff_cnt_en;

reg           crc_enable;

reg     [2:0] eof_cnt;

wire   [14:0] calculated_crc;

wire   [15:0] r_calculated_crc;

wire          remote_rq;

wire    [3:0] limited_data_len;

wire          form_error;

wire          set_form_error;

reg           transmitting;

reg           error_frame;

reg           enable_error_cnt2;

reg     [2:0] error_cnt1;

reg     [2:0] error_cnt2;

reg           tx;

reg           crc_error;

reg           priority_lost;

reg           tx_q;

wire          error_frame_ended;

wire          bit_error = 0; // FIX ME !!!

wire          acknowledge_error;

reg           need_to_tx; // When the CAN core has something to transmit and a dominant bit is sampled at the third bit

                          // of intermission, it starts reading the identifier (and transmitting its own). // FIX ME !!!

wire          overload_needed = 0;  // When receiver is busy, it needs to send overload frame. Only 2 overload frames are allowed to

                                    // be send in a row. Counter?   FIX ME

wire          id_ok;        // If received ID matches ID set in registers

wire          no_byte0;     // There is no byte 0 (RTR bit set to 1 or DLC field equal to 0). Signal used for acceptance filter.

wire          no_byte1;     // There is no byte 1 (RTR bit set to 1 or DLC field equal to 1). Signal used for acceptance filter.

reg     [3:0] data_cnt;     // Counting the data bytes that are written to FIFO

reg     [2:0] header_cnt;   // Counting header length

reg           wr_fifo;      // Write data and header to 64-byte fifo

reg     [7:0] data_for_fifo;// Multiplexed data that is stored to 64-byte fifo

reg     [5:0] tx_pointer;

reg           tx_bit;

reg           tx_state;

reg           finish_msg;

wire    [2:0] header_len;

wire          storing_header;

wire    [3:0] limited_data_len_minus1;

wire          reset_wr_fifo;

wire          no_error;

assign go_rx_idle     =                   sample_point &  sampled_bit & rx_inter & (bit_cnt == 2);  // Look the following line for TX

//assign go_rx_id1      =                   sample_point &  (~sampled_bit) & (rx_idle | rx_inter & (bit_cnt == 2) & need_to_tx);

assign go_rx_id1      =                   sample_point &  (~sampled_bit) & (rx_idle | rx_inter & (bit_cnt == 2));

assign go_rx_rtr1     = (~bit_de_stuff) & sample_point &  rx_id1  & (bit_cnt == 10);

assign go_rx_ide      = (~bit_de_stuff) & sample_point &  rx_rtr1;

assign go_rx_id2      = (~bit_de_stuff) & sample_point &  rx_ide  &   sampled_bit;

assign go_rx_rtr2     = (~bit_de_stuff) & sample_point &  rx_id2  & (bit_cnt == 17);

assign go_rx_r1       = (~bit_de_stuff) & sample_point &  rx_rtr2;

assign go_rx_r0       = (~bit_de_stuff) & sample_point & (rx_ide  & (~sampled_bit) | rx_r1);

assign go_rx_dlc      = (~bit_de_stuff) & sample_point &  rx_r0;

assign go_rx_data     = (~bit_de_stuff) & sample_point &  rx_dlc  & (bit_cnt == 3) &  (sampled_bit   |   (|data_len[2:0])) & (~remote_rq);

assign go_rx_crc      = (~bit_de_stuff) & sample_point & (rx_dlc  & (bit_cnt == 3) & ((~sampled_bit) & (~(|data_len[2:0])) | remote_rq) |

                                                          rx_data & (bit_cnt == ((limited_data_len<<3) - 1'b1)));

assign go_rx_crc_lim  = (~bit_de_stuff) & sample_point &  rx_crc  & (bit_cnt == 14);

assign go_rx_ack      =                   sample_point &  rx_crc_lim;

assign go_rx_ack_lim  =                   sample_point &  rx_ack;

assign go_rx_eof      =                   sample_point &  rx_ack_lim  | (~reset_mode) & reset_mode_q;

assign go_rx_inter    =                 ((sample_point &  rx_eof  & (eof_cnt == 6)) | error_frame_ended) & (~overload_needed);

assign go_error_frame = form_error | stuff_error | bit_error | acknowledge_error | (crc_error & go_rx_eof);

assign error_frame_ended = (error_cnt2 == 7) & tx_point;

assign go_overload_frame = ((sample_point &  rx_eof  & (eof_cnt == 6)) | error_frame_ended) & overload_needed |

                             sample_point & (~sampled_bit) & rx_inter & ((bit_cnt == 0) | (bit_cnt == 1))     |

                             sample_point & (~sampled_bit) & (error_cnt2 == 7)

                            ;

assign go_crc_enable  = hard_sync | go_tx;

assign rst_crc_enable = go_rx_crc;

assign bit_de_stuff_set   = go_rx_id1;

assign bit_de_stuff_reset = go_rx_crc_lim | reset_mode | go_error_frame;

assign remote_rq = ((~ide) & rtr1) | (ide & rtr2);

assign limited_data_len = (data_len < 8)? data_len : 4'h8;

assign acknowledge_error = rx_ack & sample_point & sampled_bit & tx_state;

// Rx idle state

always @ (posedge clk or posedge rst)

begin

  if (rst)

    rx_idle <= 1'b0;

  else if (reset_mode | go_rx_id1 | error_frame)

    rx_idle <=#Tp 1'b0;

  else if (go_rx_idle)

    rx_idle <=#Tp 1'b1;

end

// Rx id1 state

always @ (posedge clk or posedge rst)

begin

  if (rst)

    rx_id1 <= 1'b0;

  else if (reset_mode | go_rx_rtr1 | error_frame)

    rx_id1 <=#Tp 1'b0;

  else if (go_rx_id1)

    rx_id1 <=#Tp 1'b1;

end

// Rx rtr1 state

always @ (posedge clk or posedge rst)

begin

  if (rst)

    rx_rtr1 <= 1'b0;

  else if (reset_mode | go_rx_ide | error_frame)

    rx_rtr1 <=#Tp 1'b0;

  else if (go_rx_rtr1)

    rx_rtr1 <=#Tp 1'b1;

end

// Rx ide state

always @ (posedge clk or posedge rst)

begin

  if (rst)

    rx_ide <= 1'b0;

  else if (reset_mode | go_rx_r0 | go_rx_id2 | error_frame)

    rx_ide <=#Tp 1'b0;

  else if (go_rx_ide)

    rx_ide <=#Tp 1'b1;

end

// Rx id2 state

always @ (posedge clk or posedge rst)

begin

  if (rst)

    rx_id2 <= 1'b0;

  else if (reset_mode | go_rx_rtr2 | error_frame)

    rx_id2 <=#Tp 1'b0;

  else if (go_rx_id2)

    rx_id2 <=#Tp 1'b1;

end

// Rx rtr2 state

always @ (posedge clk or posedge rst)

begin

  if (rst)

    rx_rtr2 <= 1'b0;

  else if (reset_mode | go_rx_r1 | error_frame)

    rx_rtr2 <=#Tp 1'b0;

  else if (go_rx_rtr2)

    rx_rtr2 <=#Tp 1'b1;

end

// Rx r0 state

always @ (posedge clk or posedge rst)

begin

  if (rst)

    rx_r1 <= 1'b0;

  else if (reset_mode | go_rx_r0 | error_frame)

    rx_r1 <=#Tp 1'b0;

  else if (go_rx_r1)

    rx_r1 <=#Tp 1'b1;

end

// Rx r0 state

always @ (posedge clk or posedge rst)

begin

  if (rst)

    rx_r0 <= 1'b0;

  else if (reset_mode | go_rx_dlc | error_frame)

    rx_r0 <=#Tp 1'b0;

  else if (go_rx_r0)

    rx_r0 <=#Tp 1'b1;

end

// Rx dlc state

always @ (posedge clk or posedge rst)

begin

  if (rst)

    rx_dlc <= 1'b0;

  else if (reset_mode | go_rx_data | go_rx_crc | error_frame)

    rx_dlc <=#Tp 1'b0;

  else if (go_rx_dlc)

    rx_dlc <=#Tp 1'b1;

end

// Rx data state

always @ (posedge clk or posedge rst)

begin

  if (rst)

    rx_data <= 1'b0;

  else if (reset_mode | go_rx_crc | error_frame)

    rx_data <=#Tp 1'b0;

  else if (go_rx_data)

    rx_data <=#Tp 1'b1;

end

// Rx crc state

always @ (posedge clk or posedge rst)

begin

  if (rst)

    rx_crc <= 1'b0;

  else if (reset_mode | go_rx_crc_lim | error_frame)

    rx_crc <=#Tp 1'b0;

  else if (go_rx_crc)

    rx_crc <=#Tp 1'b1;

end

// Rx crc delimiter state

always @ (posedge clk or posedge rst)

begin

  if (rst)

    rx_crc_lim <= 1'b0;

  else if (reset_mode | go_rx_ack | error_frame)

    rx_crc_lim <=#Tp 1'b0;

  else if (go_rx_crc_lim)

    rx_crc_lim <=#Tp 1'b1;

end

// Rx ack state

always @ (posedge clk or posedge rst)

begin

  if (rst)

    rx_ack <= 1'b0;

  else if (reset_mode | go_rx_ack_lim | error_frame)

    rx_ack <=#Tp 1'b0;

  else if (go_rx_ack)

    rx_ack <=#Tp 1'b1;

end

// Rx ack delimiter state

always @ (posedge clk or posedge rst)

begin

  if (rst)

    rx_ack_lim <= 1'b0;

  else if (reset_mode | go_rx_eof | error_frame)

    rx_ack_lim <=#Tp 1'b0;

  else if (go_rx_ack_lim)

    rx_ack_lim <=#Tp 1'b1;

end

// Rx eof state

always @ (posedge clk or posedge rst)

begin

  if (rst)

    rx_eof <= 1'b0;

  else if (go_rx_inter | error_frame)

    rx_eof <=#Tp 1'b0;

  else if (go_rx_eof)

    rx_eof <=#Tp 1'b1;

end

// Interframe space

always @ (posedge clk or posedge rst)

begin

  if (rst)

    rx_inter <= 1'b0;

  else if (go_rx_idle | go_rx_id1 | go_overload_frame | go_error_frame)

    rx_inter <=#Tp 1'b0;

  else if (go_rx_inter)

    rx_inter <=#Tp 1'b1;

end

// ID register

always @ (posedge clk or posedge rst)

begin

  if (rst)

    id <= 0;

  else if (sample_point & (rx_id1 | rx_id2) & (~bit_de_stuff))

    id <=#Tp {id[27:0], sampled_bit};

end

// rtr1 bit

always @ (posedge clk or posedge rst)

begin

  if (rst)

    rtr1 <= 0;

  else if (sample_point & rx_rtr1 & (~bit_de_stuff))

    rtr1 <=#Tp sampled_bit;

end

// rtr2 bit

always @ (posedge clk or posedge rst)

begin

  if (rst)

    rtr2 <= 0;

  else if (sample_point & rx_rtr2 & (~bit_de_stuff))

    rtr2 <=#Tp sampled_bit;

end

// ide bit

always @ (posedge clk or posedge rst)

begin

  if (rst)

    ide <= 0;

  else if (sample_point & rx_ide & (~bit_de_stuff))

    ide <=#Tp sampled_bit;

end

// Data length

always @ (posedge clk or posedge rst)

begin

  if (rst)

    data_len <= 0;

  else if (sample_point & rx_dlc & (~bit_de_stuff))

    data_len <=#Tp {data_len[2:0], sampled_bit};

end

// Data

always @ (posedge clk or posedge rst)

begin

  if (rst)

    tmp_data <= 0;

  else if (sample_point & rx_data & (~bit_de_stuff))

    tmp_data <=#Tp {tmp_data[6:0], sampled_bit};

end

always @ (posedge clk or posedge rst)

begin

  if (rst)

    write_data_to_tmp_fifo <= 0;

  else if (sample_point & rx_data & (~bit_de_stuff) & (&bit_cnt[2:0]))

    write_data_to_tmp_fifo <=#Tp 1'b1;

  else