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- /////////////////////////////////////////////////////////////////////
- //// ////
- //// 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 1.1 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 1.7 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
- end
- endmodule
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