/////////////////////////////////////////////////////////////////////////                                                             ////////  WISHBONE rev.B2 compliant I2C Master byte-controller       ////////                                                             ////////                                                             ////////  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_byte_ctrl.v,v 1.7 2004/02/18 11:40:46 rherveille Exp $////  $Date: 2004/02/18 11:40:46 $//  $Revision: 1.7 $//  $Author: rherveille $//  $Locker:  $//  $State: Exp $//// Change History://               $Log: i2c_master_byte_ctrl.v,v $//               Revision 1.7  2004/02/18 11:40:46  rherveille//               Fixed a potential bug in the statemachine. During a 'stop' 2 cmd_ack signals were generated. Possibly canceling a new start command.////               Revision 1.6  2003/08/09 07:01:33  rherveille//               Fixed a bug in the Arbitration Lost generation caused by delay on the (external) sda line.//               Fixed a potential bug in the byte controller's host-acknowledge generation.////               Revision 1.5  2002/12/26 15:02:32  rherveille//               Core is now a Multimaster I2C controller////               Revision 1.4  2002/11/30 22:24:40  rherveille//               Cleaned up code////               Revision 1.3  2001/11/05 11:59:25  rherveille//               Fixed wb_ack_o generation bug.//               Fixed bug in the byte_controller statemachine.//               Added headers.//// synopsys translate_off`include "timescale.v"// synopsys translate_on`include "i2c_master_defines.v"module i2c_master_byte_ctrl (	clk, rst, nReset, ena, clk_cnt, start, stop, read, write, ack_in, din,	cmd_ack, ack_out, dout, i2c_busy, i2c_al, scl_i, scl_o, scl_oen, sda_i, sda_o, sda_oen );	//	// inputs & outputs	//	input clk;     // master clock	input rst;     // synchronous active high reset	input nReset;  // asynchronous active low reset	input ena;     // core enable signal	input [15:0] clk_cnt; // 4x SCL	// control inputs	input       start;	input       stop;	input       read;	input       write;	input       ack_in;	input [7:0] din;	// status outputs	output       cmd_ack;	reg cmd_ack;	output       ack_out;	reg ack_out;	output       i2c_busy;	output       i2c_al;	output [7:0] dout;	// I2C signals	input  scl_i;	output scl_o;	output scl_oen;	input  sda_i;	output sda_o;	output sda_oen;	//	// Variable declarations	//	// statemachine	parameter [4:0] ST_IDLE  = 5'b0_0000;	parameter [4:0] ST_START = 5'b0_0001;	parameter [4:0] ST_READ  = 5'b0_0010;	parameter [4:0] ST_WRITE = 5'b0_0100;	parameter [4:0] ST_ACK   = 5'b0_1000;	parameter [4:0] ST_STOP  = 5'b1_0000;	// signals for bit_controller	reg  [3:0] core_cmd;	reg        core_txd;	wire       core_ack, core_rxd;	// signals for shift register	reg [7:0] sr; //8bit shift register	reg       shift, ld;	// signals for state machine	wire       go;	reg  [2:0] dcnt;	wire       cnt_done;	//	// Module body	//	// hookup bit_controller	i2c_master_bit_ctrl bit_controller (		.clk     ( clk      ),		.rst     ( rst      ),		.nReset  ( nReset   ),		.ena     ( ena      ),		.clk_cnt ( clk_cnt  ),		.cmd     ( core_cmd ),		.cmd_ack ( core_ack ),		.busy    ( i2c_busy ),		.al      ( i2c_al   ),		.din     ( core_txd ),		.dout    ( core_rxd ),		.scl_i   ( scl_i    ),		.scl_o   ( scl_o    ),		.scl_oen ( scl_oen  ),		.sda_i   ( sda_i    ),		.sda_o   ( sda_o    ),		.sda_oen ( sda_oen  )	);	// generate go-signal	assign go = (read | write | stop) & ~cmd_ack;	// assign dout output to shift-register	assign dout = sr;	// generate shift register	always @(posedge clk or negedge nReset)	  if (!nReset)	    sr <= #1 8'h0;	  else if (rst)	    sr <= #1 8'h0;	  else if (ld)	    sr <= #1 din;	  else if (shift)	    sr <= #1 {sr[6:0], core_rxd};	// generate counter	always @(posedge clk or negedge nReset)	  if (!nReset)	    dcnt <= #1 3'h0;	  else if (rst)	    dcnt <= #1 3'h0;	  else if (ld)	    dcnt <= #1 3'h7;	  else if (shift)	    dcnt <= #1 dcnt - 3'h1;	assign cnt_done = ~(|dcnt);	//	// state machine	//	reg [4:0] c_state; // synopsis enum_state	always @(posedge clk or negedge nReset)	  if (!nReset)	    begin	        core_cmd <= #1 `I2C_CMD_NOP;	        core_txd <= #1 1'b0;	        shift    <= #1 1'b0;	        ld       <= #1 1'b0;	        cmd_ack  <= #1 1'b0;	        c_state  <= #1 ST_IDLE;	        ack_out  <= #1 1'b0;	    end	  else if (rst | i2c_al)	   begin	       core_cmd <= #1 `I2C_CMD_NOP;	       core_txd <= #1 1'b0;	       shift    <= #1 1'b0;	       ld       <= #1 1'b0;	       cmd_ack  <= #1 1'b0;	       c_state  <= #1 ST_IDLE;	       ack_out  <= #1 1'b0;	   end	else	  begin	      // initially reset all signals	      core_txd <= #1 sr[7];	      shift    <= #1 1'b0;	      ld       <= #1 1'b0;	      cmd_ack  <= #1 1'b0;	      case (c_state) // synopsys full_case parallel_case	        ST_IDLE:	          if (go)	            begin	                if (start)	                  begin	                      c_state  <= #1 ST_START;	                      core_cmd <= #1 `I2C_CMD_START;	                  end	                else if (read)	                  begin	                      c_state  <= #1 ST_READ;	                      core_cmd <= #1 `I2C_CMD_READ;	                  end	                else if (write)	                  begin	                      c_state  <= #1 ST_WRITE;	                      core_cmd <= #1 `I2C_CMD_WRITE;	                  end	                else // stop	                  begin	                      c_state  <= #1 ST_STOP;	                      core_cmd <= #1 `I2C_CMD_STOP;	                  end	                ld <= #1 1'b1;	            end	        ST_START:	          if (core_ack)	            begin	                if (read)	                  begin	                      c_state  <= #1 ST_READ;	                      core_cmd <= #1 `I2C_CMD_READ;	                  end	                else	                  begin	                      c_state  <= #1 ST_WRITE;	                      core_cmd <= #1 `I2C_CMD_WRITE;	                  end	                ld <= #1 1'b1;	            end	        ST_WRITE:	          if (core_ack)	            if (cnt_done)	              begin	                  c_state  <= #1 ST_ACK;	                  core_cmd <= #1 `I2C_CMD_READ;	              end	            else	              begin	                  c_state  <= #1 ST_WRITE;       // stay in same state	                  core_cmd <= #1 `I2C_CMD_WRITE; // write next bit	                  shift    <= #1 1'b1;	              end	        ST_READ:	          if (core_ack)	            begin	                if (cnt_done)	                  begin	                      c_state  <= #1 ST_ACK;	                      core_cmd <= #1 `I2C_CMD_WRITE;	                  end	                else	                  begin	                      c_state  <= #1 ST_READ;       // stay in same state	                      core_cmd <= #1 `I2C_CMD_READ; // read next bit	                  end	                shift    <= #1 1'b1;	                core_txd <= #1 ack_in;	            end	        ST_ACK:	          if (core_ack)	            begin	               if (stop)	                 begin	                     c_state  <= #1 ST_STOP;	                     core_cmd <= #1 `I2C_CMD_STOP;	                 end	               else	                 begin	                     c_state  <= #1 ST_IDLE;	                     core_cmd <= #1 `I2C_CMD_NOP;	                     // generate command acknowledge signal	                     cmd_ack  <= #1 1'b1;	                 end	                 // assign ack_out output to bit_controller_rxd (contains last received bit)	                 ack_out <= #1 core_rxd;	                 core_txd <= #1 1'b1;	             end	           else	             core_txd <= #1 ack_in;	        ST_STOP:	          if (core_ack)	            begin	                c_state  <= #1 ST_IDLE;	                core_cmd <= #1 `I2C_CMD_NOP;	                // generate command acknowledge signal	                cmd_ack  <= #1 1'b1;	            end	      endcase	  endendmodule