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- /////////////////////////////////////////////////////////////////////
- //// ////
- //// 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 1.1 2008-11-08 13:15:10 sfielding Exp $
- //
- // $Date: 2008-11-08 13:15:10 $
- // $Revision: 1.1 $
- // $Author: sfielding $
- // $Locker: $
- // $State: Exp $
- //
- // Change History:
- // $Log: not supported by cvs2svn $
- // 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
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