/////////////////////////////////////////////////////////////////////////                                                             ////////  WISHBONE revB.2 compliant I2C Master controller Top-level  ////////                                                             ////////                                                             ////////  Author: Richard Herveille                                  ////////          richard@asics.ws                                   ////////          www.asics.ws                                       ////////                                                             ////////  Downloaded from: http://www.opencores.org/projects/i2c/    ////////                                                             /////////////////////////////////////////////////////////////////////////////                                                             //////// Copyright (C) 2001 Richard Herveille                        ////////                    richard@asics.ws                         ////////                                                             //////// 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 SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY     //////// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED   //////// TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS   //////// FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL THE AUTHOR      //////// OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,         //////// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES    //////// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE   //////// GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR        //////// BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF  //////// LIABILITY, WHETHER IN  CONTRACT, STRICT LIABILITY, OR TORT  //////// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT  //////// OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE         //////// POSSIBILITY OF SUCH DAMAGE.                                 ////////                                                             ///////////////////////////////////////////////////////////////////////////  CVS Log////  $Id: i2c_master_top.v,v 1.11 2005/02/27 09:26:24 rherveille Exp $////  $Date: 2005/02/27 09:26:24 $//  $Revision: 1.11 $//  $Author: rherveille $//  $Locker:  $//  $State: Exp $//// Change History://               $Log: i2c_master_top.v,v $//               Revision 1.11  2005/02/27 09:26:24  rherveille//               Fixed register overwrite issue.//               Removed full_case pragma, replaced it by a default statement.////               Revision 1.10  2003/09/01 10:34:38  rherveille//               Fix a blocking vs. non-blocking error in the wb_dat output mux.////               Revision 1.9  2003/01/09 16:44:45  rherveille//               Fixed a bug in the Command Register declaration.////               Revision 1.8  2002/12/26 16:05:12  rherveille//               Small code simplifications////               Revision 1.7  2002/12/26 15:02:32  rherveille//               Core is now a Multimaster I2C controller////               Revision 1.6  2002/11/30 22:24:40  rherveille//               Cleaned up code////               Revision 1.5  2001/11/10 10:52:55  rherveille//               Changed PRER reset value from 0x0000 to 0xffff, conform specs.//// synopsys translate_off`include "timescale.v"// synopsys translate_on`include "i2c_master_defines.v"module i2c_master_top(	wb_clk_i, wb_rst_i, arst_i, wb_adr_i, wb_dat_i, wb_dat_o,	wb_we_i, wb_stb_i, wb_cyc_i, wb_ack_o, wb_inta_o,	scl_pad_i, scl_pad_o, scl_padoen_o, sda_pad_i, sda_pad_o, sda_padoen_o );	// parameters	parameter ARST_LVL = 1'b0; // asynchronous reset level	//	// inputs & outputs	//	// wishbone signals	input        wb_clk_i;     // master clock input	input        wb_rst_i;     // synchronous active high reset	input        arst_i;       // asynchronous reset	input  [2:0] wb_adr_i;     // lower address bits	input  [7:0] wb_dat_i;     // databus input	output [7:0] wb_dat_o;     // databus output	input        wb_we_i;      // write enable input	input        wb_stb_i;     // stobe/core select signal	input        wb_cyc_i;     // valid bus cycle input	output       wb_ack_o;     // bus cycle acknowledge output	output       wb_inta_o;    // interrupt request signal output	reg [7:0] wb_dat_o;	reg wb_ack_o;	reg wb_inta_o;	// I2C signals	// i2c clock line	input  scl_pad_i;       // SCL-line input	output scl_pad_o;       // SCL-line output (always 1'b0)	output scl_padoen_o;    // SCL-line output enable (active low)	// i2c data line	input  sda_pad_i;       // SDA-line input	output sda_pad_o;       // SDA-line output (always 1'b0)	output sda_padoen_o;    // SDA-line output enable (active low)	//	// variable declarations	//	// registers	reg  [15:0] prer; // clock prescale register	reg  [ 7:0] ctr;  // control register	reg  [ 7:0] txr;  // transmit register	wire [ 7:0] rxr;  // receive register	reg  [ 7:0] cr;   // command register	wire [ 7:0] sr;   // status register	// done signal: command completed, clear command register	wire done;	// core enable signal	wire core_en;	wire ien;	// status register signals	wire irxack;	reg  rxack;       // received aknowledge from slave	reg  tip;         // transfer in progress	reg  irq_flag;    // interrupt pending flag	wire i2c_busy;    // bus busy (start signal detected)	wire i2c_al;      // i2c bus arbitration lost	reg  al;          // status register arbitration lost bit	//	// module body	//	// generate internal reset	wire rst_i = arst_i ^ ARST_LVL;	// generate wishbone signals	wire wb_wacc = wb_cyc_i & wb_stb_i & wb_we_i;	// generate acknowledge output signal	always @(posedge wb_clk_i)	  wb_ack_o <= #1 wb_cyc_i & wb_stb_i & ~wb_ack_o; // because timing is always honored	// assign DAT_O	always @(posedge wb_clk_i)	begin	  case (wb_adr_i) // synopsis parallel_case	    3'b000: wb_dat_o <= #1 prer[ 7:0];	    3'b001: wb_dat_o <= #1 prer[15:8];	    3'b010: wb_dat_o <= #1 ctr;	    3'b011: wb_dat_o <= #1 rxr; // write is transmit register (txr)	    3'b100: wb_dat_o <= #1 sr;  // write is command register (cr)	    3'b101: wb_dat_o <= #1 txr;	    3'b110: wb_dat_o <= #1 cr;	    3'b111: wb_dat_o <= #1 0;   // reserved	  endcase	end	// generate registers	always @(posedge wb_clk_i or negedge rst_i)	  if (!rst_i)	    begin	        prer <= #1 16'hffff;	        ctr  <= #1  8'h0;	        txr  <= #1  8'h0;	    end	  else if (wb_rst_i)	    begin	        prer <= #1 16'hffff;	        ctr  <= #1  8'h0;	        txr  <= #1  8'h0;	    end	  else	    if (wb_wacc)	      case (wb_adr_i) // synopsis parallel_case	         3'b000 : prer [ 7:0] <= #1 wb_dat_i;	         3'b001 : prer [15:8] <= #1 wb_dat_i;	         3'b010 : ctr         <= #1 wb_dat_i;	         3'b011 : txr         <= #1 wb_dat_i;	         default: ;	      endcase	// generate command register (special case)	always @(posedge wb_clk_i or negedge rst_i)	  if (~rst_i)	    cr <= #1 8'h0;	  else if (wb_rst_i)	    cr <= #1 8'h0;	  else if (wb_wacc)	    begin	        if (core_en & (wb_adr_i == 3'b100) )	          cr <= #1 wb_dat_i;	    end	  else	    begin	        if (done | i2c_al)	          cr[7:4] <= #1 4'h0;           // clear command bits when done	                                        // or when aribitration lost	        cr[2:1] <= #1 2'b0;             // reserved bits	        cr[0]   <= #1 2'b0;             // clear IRQ_ACK bit	    end	// decode command register	wire sta  = cr[7];	wire sto  = cr[6];	wire rd   = cr[5];	wire wr   = cr[4];	wire ack  = cr[3];	wire iack = cr[0];	// decode control register	assign core_en = ctr[7];	assign ien = ctr[6];	// hookup byte controller block	i2c_master_byte_ctrl byte_controller (		.clk      ( wb_clk_i     ),		.rst      ( wb_rst_i     ),		.nReset   ( rst_i        ),		.ena      ( core_en      ),		.clk_cnt  ( prer         ),		.start    ( sta          ),		.stop     ( sto          ),		.read     ( rd           ),		.write    ( wr           ),		.ack_in   ( ack          ),		.din      ( txr          ),		.cmd_ack  ( done         ),		.ack_out  ( irxack       ),		.dout     ( rxr          ),		.i2c_busy ( i2c_busy     ),		.i2c_al   ( i2c_al       ),		.scl_i    ( scl_pad_i    ),		.scl_o    ( scl_pad_o    ),		.scl_oen  ( scl_padoen_o ),		.sda_i    ( sda_pad_i    ),		.sda_o    ( sda_pad_o    ),		.sda_oen  ( sda_padoen_o )	);	// status register block + interrupt request signal	always @(posedge wb_clk_i or negedge rst_i)	  if (!rst_i)	    begin	        al       <= #1 1'b0;	        rxack    <= #1 1'b0;	        tip      <= #1 1'b0;	        irq_flag <= #1 1'b0;	    end	  else if (wb_rst_i)	    begin	        al       <= #1 1'b0;	        rxack    <= #1 1'b0;	        tip      <= #1 1'b0;	        irq_flag <= #1 1'b0;	    end	  else	    begin	        al       <= #1 i2c_al | (al & ~sta);	        rxack    <= #1 irxack;	        tip      <= #1 (rd | wr);	        irq_flag <= #1 (done | i2c_al | irq_flag) & ~iack; // interrupt request flag is always generated	    end	// generate interrupt request signals	always @(posedge wb_clk_i or negedge rst_i)	  if (!rst_i)	    wb_inta_o <= #1 1'b0;	  else if (wb_rst_i)	    wb_inta_o <= #1 1'b0;	  else	    wb_inta_o <= #1 irq_flag && ien; // interrupt signal is only generated when IEN (interrupt enable bit is set)	// assign status register bits	assign sr[7]   = rxack;	assign sr[6]   = i2c_busy;	assign sr[5]   = al;	assign sr[4:2] = 3'h0; // reserved	assign sr[1]   = tip;	assign sr[0]   = irq_flag;endmodule