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

////                                                              ////

////  can_registers.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                     ////

////                                                              ////

//// The CAN protocol is developed by Robert Bosch GmbH and       ////

//// protected by patents. Anybody who wants to implement this    ////

//// CAN IP core on silicon has to obtain a CAN protocol license  ////

//// from Bosch.                                                  ////

////                                                              ////

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

//

// CVS Revision History

//

// $Log: not supported by cvs2svn $

// Revision 1.35  2004/11/30 15:08:26  igorm

// irq is cleared after the release_buffer command. This bug was entered with

// changes for the edge triggered interrupts.

//

// Revision 1.34  2004/11/18 12:39:43  igorm

// Fixes for compatibility after the SW reset.

//

// Revision 1.33  2004/10/25 11:44:38  igorm

// Interrupt is always cleared for one clock after the irq register is read.

// This fixes problems when CPU is using IRQs that are edge triggered.

//

// Revision 1.32  2004/05/12 15:58:41  igorm

// Core improved to pass all tests with the Bosch VHDL Reference system.

//

// Revision 1.31  2003/09/25 18:55:49  mohor

// Synchronization changed, error counters fixed.

//

// Revision 1.30  2003/07/16 15:19:34  mohor

// Fixed according to the linter.

// Case statement for data_out joined.

//

// Revision 1.29  2003/07/10 01:59:04  tadejm

// Synchronization fixed. In some strange cases it didn't work according to

// the VHDL reference model.

//

// Revision 1.28  2003/07/07 11:21:37  mohor

// Little fixes (to fix warnings).

//

// Revision 1.27  2003/06/22 09:43:03  mohor

// synthesi full_case parallel_case fixed.

//

// Revision 1.26  2003/06/22 01:33:14  mohor

// clkout is clk/2 after the reset.

//

// Revision 1.25  2003/06/21 12:16:30  mohor

// paralel_case and full_case compiler directives added to case statements.

//

// Revision 1.24  2003/06/09 11:22:54  mohor

// data_out is already registered in the can_top.v file.

//

// Revision 1.23  2003/04/15 15:31:24  mohor

// Some features are supported in extended mode only (listen_only_mode...).

//

// Revision 1.22  2003/03/20 16:58:50  mohor

// unix.

//

// Revision 1.20  2003/03/11 16:31:05  mohor

// Mux used for clkout to avoid "gated clocks warning".

//

// Revision 1.19  2003/03/10 17:34:25  mohor

// Doubled declarations removed.

//

// Revision 1.18  2003/03/01 22:52:11  mohor

// Data is latched on read.

//

// Revision 1.17  2003/02/19 15:09:02  mohor

// Incomplete sensitivity list fixed.

//

// Revision 1.16  2003/02/19 14:44:03  mohor

// CAN core finished. Host interface added. Registers finished.

// Synchronization to the wishbone finished.

//

// Revision 1.15  2003/02/18 00:10:15  mohor

// Most of the registers added. Registers "arbitration lost capture", "error code

// capture" + few more still need to be added.

//

// Revision 1.14  2003/02/14 20:17:01  mohor

// Several registers added. Not finished, yet.

//

// Revision 1.13  2003/02/12 14:25:30  mohor

// abort_tx added.

//

// Revision 1.12  2003/02/11 00:56:06  mohor

// Wishbone interface added.

//

// Revision 1.11  2003/02/09 02:24:33  mohor

// Bosch license warning added. Error counters finished. Overload frames

// still need to be fixed.

//

// Revision 1.10  2003/01/31 01:13:38  mohor

// backup.

//

// Revision 1.9  2003/01/15 13:16:48  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 1.8  2003/01/14 17:25:09  mohor

// Addresses corrected to decimal values (previously hex).

//

// Revision 1.7  2003/01/14 12:19:35  mohor

// rx_fifo is now working.

//

// Revision 1.6  2003/01/10 17:51:34  mohor

// Temporary version (backup).

//

// Revision 1.5  2003/01/09 14:46:58  mohor

// Temporary files (backup).

//

// Revision 1.4  2003/01/08 02:10:55  mohor

// Acceptance filter added.

//

// Revision 1.3  2002/12/27 00:12:52  mohor

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

//

// Revision 1.2  2002/12/26 16:00:34  mohor

// Testbench define file added. Clock divider register added.

//

// 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_registers

(

  clk,

  rst,

  cs,

  we,

  addr,

  data_in,

  data_out,

  irq_n,

  sample_point,

  transmitting,

  set_reset_mode,

  node_bus_off,

  error_status,

  rx_err_cnt,

  tx_err_cnt,

  transmit_status,

  receive_status,

  tx_successful,

  need_to_tx,

  overrun,

  info_empty,

  set_bus_error_irq,

  set_arbitration_lost_irq,

  arbitration_lost_capture,

  node_error_passive,

  node_error_active,

  rx_message_counter,

  /* Mode register */

  reset_mode,

  listen_only_mode,

  acceptance_filter_mode,

  self_test_mode,

  /* Command register */

  clear_data_overrun,

  release_buffer,

  abort_tx,

  tx_request,

  self_rx_request,

  single_shot_transmission,

  tx_state,

  tx_state_q,

  overload_request,

  overload_frame,

  /* Arbitration Lost Capture Register */

  read_arbitration_lost_capture_reg,

  /* Error Code Capture Register */

  read_error_code_capture_reg,

  error_capture_code,

  /* Bus Timing 0 register */

  baud_r_presc,

  sync_jump_width,

  /* Bus Timing 1 register */

  time_segment1,

  time_segment2,

  triple_sampling,

  /* Error Warning Limit register */

  error_warning_limit,

  /* Rx Error Counter register */

  we_rx_err_cnt,

  /* Tx Error Counter register */

  we_tx_err_cnt,

  /* Clock Divider register */

  extended_mode,

  clkout,

  /* 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 */

);

parameter Tp = 1;

input         clk;

input         rst;

input         cs;

input         we;

input   [7:0] addr;

input   [7:0] data_in;

output  [7:0] data_out;

reg     [7:0] data_out;

output        irq_n;

input         sample_point;

input         transmitting;

input         set_reset_mode;

input         node_bus_off;

input         error_status;

input   [7:0] rx_err_cnt;

input   [7:0] tx_err_cnt;

input         transmit_status;

input         receive_status;

input         tx_successful;

input         need_to_tx;

input         overrun;

input         info_empty;

input         set_bus_error_irq;

input         set_arbitration_lost_irq;

input   [4:0] arbitration_lost_capture;

input         node_error_passive;

input         node_error_active;

input   [6:0] rx_message_counter;

/* Mode register */

output        reset_mode;

output        listen_only_mode;

output        acceptance_filter_mode;

output        self_test_mode;

/* Command register */

output        clear_data_overrun;

output        release_buffer;

output        abort_tx;

output        tx_request;

output        self_rx_request;

output        single_shot_transmission;

input         tx_state;

input         tx_state_q;

output        overload_request;

input         overload_frame;

/* Arbitration Lost Capture Register */

output        read_arbitration_lost_capture_reg;

/* Error Code Capture Register */

output        read_error_code_capture_reg;

input   [7:0] error_capture_code;

/* Bus Timing 0 register */

output  [5:0] baud_r_presc;

output  [1:0] sync_jump_width;

/* Bus Timing 1 register */

output  [3:0] time_segment1;

output  [2:0] time_segment2;

output        triple_sampling;

/* Error Warning Limit register */

output  [7:0] error_warning_limit;

/* Rx Error Counter register */

output        we_rx_err_cnt;

/* Tx Error Counter register */

output        we_tx_err_cnt;

/* Clock Divider register */

output        extended_mode;

output        clkout;

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

/* Acceptance code register */

output  [7:0] acceptance_code_0;

/* Acceptance mask register */

output  [7:0] acceptance_mask_0;

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

/* This section is for EXTENDED mode */

/* Acceptance code register */

output  [7:0] acceptance_code_1;

output  [7:0] acceptance_code_2;

output  [7:0] acceptance_code_3;

/* Acceptance mask register */

output  [7:0] acceptance_mask_1;

output  [7:0] acceptance_mask_2;

output  [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 */

output  [7:0] tx_data_0;

output  [7:0] tx_data_1;

output  [7:0] tx_data_2;

output  [7:0] tx_data_3;

output  [7:0] tx_data_4;

output  [7:0] tx_data_5;

output  [7:0] tx_data_6;

output  [7:0] tx_data_7;

output  [7:0] tx_data_8;

output  [7:0] tx_data_9;

output  [7:0] tx_data_10;

output  [7:0] tx_data_11;

output  [7:0] tx_data_12;

/* End: Tx data registers */

reg           tx_successful_q;

reg           overrun_q;

reg           overrun_status;

reg           transmission_complete;

reg           transmit_buffer_status_q;

reg           receive_buffer_status;

reg           error_status_q;

reg           node_bus_off_q;

reg           node_error_passive_q;

reg           transmit_buffer_status;

reg           single_shot_transmission;

reg           self_rx_request;

reg           irq_n;

// Some interrupts exist in basic mode and in extended mode. Since they are in different registers they need to be multiplexed.

wire          data_overrun_irq_en;

wire          error_warning_irq_en;

wire          transmit_irq_en;

wire          receive_irq_en;

wire    [7:0] irq_reg;

wire          irq;

wire we_mode                  = cs & we & (addr == 8'd0);

wire we_command               = cs & we & (addr == 8'd1);

wire we_bus_timing_0          = cs & we & (addr == 8'd6) & reset_mode;

wire we_bus_timing_1          = cs & we & (addr == 8'd7) & reset_mode;

wire we_clock_divider_low     = cs & we & (addr == 8'd31);

wire we_clock_divider_hi      = we_clock_divider_low & reset_mode;

wire read = cs & (~we);

wire read_irq_reg = read & (addr == 8'd3);

assign read_arbitration_lost_capture_reg = read & extended_mode & (addr == 8'd11);

assign read_error_code_capture_reg = read & extended_mode & (addr == 8'd12);

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

wire we_acceptance_code_0       = cs & we &   reset_mode  & ((~extended_mode) & (addr == 8'd4)  | extended_mode & (addr == 8'd16));

wire we_acceptance_mask_0       = cs & we &   reset_mode  & ((~extended_mode) & (addr == 8'd5)  | extended_mode & (addr == 8'd20));

wire we_tx_data_0               = cs & we & (~reset_mode) & ((~extended_mode) & (addr == 8'd10) | extended_mode & (addr == 8'd16)) & transmit_buffer_status;

wire we_tx_data_1               = cs & we & (~reset_mode) & ((~extended_mode) & (addr == 8'd11) | extended_mode & (addr == 8'd17)) & transmit_buffer_status;

wire we_tx_data_2               = cs & we & (~reset_mode) & ((~extended_mode) & (addr == 8'd12) | extended_mode & (addr == 8'd18)) & transmit_buffer_status;

wire we_tx_data_3               = cs & we & (~reset_mode) & ((~extended_mode) & (addr == 8'd13) | extended_mode & (addr == 8'd19)) & transmit_buffer_status;

wire we_tx_data_4               = cs & we & (~reset_mode) & ((~extended_mode) & (addr == 8'd14) | extended_mode & (addr == 8'd20)) & transmit_buffer_status;

wire we_tx_data_5               = cs & we & (~reset_mode) & ((~extended_mode) & (addr == 8'd15) | extended_mode & (addr == 8'd21)) & transmit_buffer_status;

wire we_tx_data_6               = cs & we & (~reset_mode) & ((~extended_mode) & (addr == 8'd16) | extended_mode & (addr == 8'd22)) & transmit_buffer_status;

wire we_tx_data_7               = cs & we & (~reset_mode) & ((~extended_mode) & (addr == 8'd17) | extended_mode & (addr == 8'd23)) & transmit_buffer_status;

wire we_tx_data_8               = cs & we & (~reset_mode) & ((~extended_mode) & (addr == 8'd18) | extended_mode & (addr == 8'd24)) & transmit_buffer_status;

wire we_tx_data_9               = cs & we & (~reset_mode) & ((~extended_mode) & (addr == 8'd19) | extended_mode & (addr == 8'd25)) & transmit_buffer_status;

wire we_tx_data_10              = cs & we & (~reset_mode) & (                                     extended_mode & (addr == 8'd26)) & transmit_buffer_status;

wire we_tx_data_11              = cs & we & (~reset_mode) & (                                     extended_mode & (addr == 8'd27)) & transmit_buffer_status;

wire we_tx_data_12              = cs & we & (~reset_mode) & (                                     extended_mode & (addr == 8'd28)) & transmit_buffer_status;

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

/* This section is for EXTENDED mode */

wire   we_interrupt_enable      = cs & we & (addr == 8'd4)  & extended_mode;

wire   we_error_warning_limit   = cs & we & (addr == 8'd13) & reset_mode & extended_mode;

assign we_rx_err_cnt            = cs & we & (addr == 8'd14) & reset_mode & extended_mode;

assign we_tx_err_cnt            = cs & we & (addr == 8'd15) & reset_mode & extended_mode;

wire   we_acceptance_code_1     = cs & we & (addr == 8'd17) & reset_mode & extended_mode;

wire   we_acceptance_code_2     = cs & we & (addr == 8'd18) & reset_mode & extended_mode;

wire   we_acceptance_code_3     = cs & we & (addr == 8'd19) & reset_mode & extended_mode;

wire   we_acceptance_mask_1     = cs & we & (addr == 8'd21) & reset_mode & extended_mode;

wire   we_acceptance_mask_2     = cs & we & (addr == 8'd22) & reset_mode & extended_mode;

wire   we_acceptance_mask_3     = cs & we & (addr == 8'd23) & reset_mode & extended_mode;

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

always @ (posedge clk)

begin

  tx_successful_q           <=#Tp tx_successful;

  overrun_q                 <=#Tp overrun;

  transmit_buffer_status_q  <=#Tp transmit_buffer_status;

  error_status_q            <=#Tp error_status;

  node_bus_off_q            <=#Tp node_bus_off;

  node_error_passive_q      <=#Tp node_error_passive;

end

/* Mode register */

wire   [0:0] mode;

wire   [4:1] mode_basic;

wire   [3:1] mode_ext;

wire         receive_irq_en_basic;

wire         transmit_irq_en_basic;

wire         error_irq_en_basic;

wire         overrun_irq_en_basic;

can_register_asyn_syn #(1, 1'h1) MODE_REG0

( .data_in(data_in[0]),

  .data_out(mode[0]),

  .we(we_mode),

  .clk(clk),

  .rst(rst),

  .rst_sync(set_reset_mode)

);

can_register_asyn #(4, 0) MODE_REG_BASIC

( .data_in(data_in[4:1]),

  .data_out(mode_basic[4:1]),

  .we(we_mode),

  .clk(clk),

  .rst(rst)

);

can_register_asyn #(3, 0) MODE_REG_EXT

( .data_in(data_in[3:1]),

  .data_out(mode_ext[3:1]),

  .we(we_mode & reset_mode),

  .clk(clk),

  .rst(rst)

);

assign reset_mode             = mode[0];

assign listen_only_mode       = extended_mode & mode_ext[1];

assign self_test_mode         = extended_mode & mode_ext[2];

assign acceptance_filter_mode = extended_mode & mode_ext[3];

assign receive_irq_en_basic  = mode_basic[1];

assign transmit_irq_en_basic = mode_basic[2];

assign error_irq_en_basic    = mode_basic[3];

assign overrun_irq_en_basic  = mode_basic[4];

/* End Mode register */

/* Command register */

wire   [4:0] command;

can_register_asyn_syn #(1, 1'h0) COMMAND_REG0

( .data_in(data_in[0]),

  .data_out(command[0]),

  .we(we_command),

  .clk(clk),

  .rst(rst),

  .rst_sync(command[0] & sample_point | reset_mode)

);

can_register_asyn_syn #(1, 1'h0) COMMAND_REG1

( .data_in(data_in[1]),

  .data_out(command[1]),

  .we(we_command),

  .clk(clk),

  .rst(rst),

  .rst_sync(sample_point & (tx_request | (abort_tx & ~transmitting)) | reset_mode)

);

can_register_asyn_syn #(2, 2'h0) COMMAND_REG

( .data_in(data_in[3:2]),

  .data_out(command[3:2]),

  .we(we_command),

  .clk(clk),

  .rst(rst),

  .rst_sync(|command[3:2] | reset_mode)

);

can_register_asyn_syn #(1, 1'h0) COMMAND_REG4

( .data_in(data_in[4]),

  .data_out(command[4]),

  .we(we_command),

  .clk(clk),

  .rst(rst),

  .rst_sync(command[4] & sample_point | reset_mode)

);

always @ (posedge clk or posedge rst)

begin

  if (rst)

    self_rx_request <= 1'b0;

  else if (command[4] & (~command[0]))

    self_rx_request <=#Tp 1'b1;

  else if ((~tx_state) & tx_state_q)

    self_rx_request <=#Tp 1'b0;

end

assign clear_data_overrun = command[3];

assign release_buffer = command[2];

assign tx_request = command[0] | command[4];

assign abort_tx = command[1] & (~tx_request);

always @ (posedge clk or posedge rst)

begin

  if (rst)

    single_shot_transmission <= 1'b0;

  else if (tx_request & command[1] & sample_point)

    single_shot_transmission <=#Tp 1'b1;

  else if ((~tx_state) & tx_state_q)

    single_shot_transmission <=#Tp 1'b0;

end

/*

can_register_asyn_syn #(1, 1'h0) COMMAND_REG_OVERLOAD  // Uncomment this to enable overload requests !!!

( .data_in(data_in[5]),

  .data_out(overload_request),

  .we(we_command),

  .clk(clk),

  .rst(rst),

  .rst_sync(overload_frame & ~overload_frame_q)

);

reg           overload_frame_q;

always @ (posedge clk or posedge rst)

begin

  if (rst)

    overload_frame_q <= 1'b0;

  else

    overload_frame_q <=#Tp overload_frame;

end

*/

assign overload_request = 0;  // Overload requests are not supported, yet !!!

/* End Command register */

/* Status register */

wire   [7:0] status;

assign status[7] = node_bus_off;

assign status[6] = error_status;

assign status[5] = transmit_status;

assign status[4] = receive_status;

assign status[3] = transmission_complete;

assign status[2] = transmit_buffer_status;

assign status[1] = overrun_status;

assign status[0] = receive_buffer_status;

always @ (posedge clk or posedge rst)

begin

  if (rst)

    transmission_complete <= 1'b1;

  else if (tx_successful & (~tx_successful_q) | abort_tx)

    transmission_complete <=#Tp 1'b1;

  else if (tx_request)

    transmission_complete <=#Tp 1'b0;

end