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/////////////////////////////////////////////////////////////////////
//// ////
//// WISHBONE rev.B2 compliant I2C Master bit-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_bit_ctrl.v,v 1.11 2004/05/07 11:02:26 rherveille Exp $
//
// $Date: 2004/05/07 11:02:26 $
// $Revision: 1.11 $
// $Author: rherveille $
// $Locker: $
// $State: Exp $
//
// Change History:
// $Log: i2c_master_bit_ctrl.v,v $
// Revision 1.11 2004/05/07 11:02:26 rherveille
// Fixed a bug where the core would signal an arbitration lost (AL bit set), when another master controls the bus and the other master generates a STOP bit.
//
// Revision 1.10 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 1.9 2003/03/10 14:26:37 rherveille
// Fixed cmd_ack generation item (no bug).
//
// Revision 1.8 2003/02/05 00:06:10 rherveille
// Fixed a bug where the core would trigger an erroneous 'arbitration lost' interrupt after being reset, when the reset pulse width < 3 clk cycles.
//
// Revision 1.7 2002/12/26 16:05:12 rherveille
// Small code simplifications
//
// Revision 1.6 2002/12/26 15:02:32 rherveille
// Core is now a Multimaster I2C controller
//
// Revision 1.5 2002/11/30 22:24:40 rherveille
// Cleaned up code
//
// Revision 1.4 2002/10/30 18:10:07 rherveille
// Fixed some reported minor start/stop generation timing issuess.
//
// Revision 1.3 2002/06/15 07:37:03 rherveille
// Fixed a small timing bug in the bit controller.\nAdded verilog simulation environment.
//
// Revision 1.2 2001/11/05 11:59:25 rherveille
// Fixed wb_ack_o generation bug.
// Fixed bug in the byte_controller statemachine.
// Added headers.
//
//
/////////////////////////////////////
// Bit controller section
/////////////////////////////////////
//
// Translate simple commands into SCL/SDA transitions
// Each command has 5 states, A/B/C/D/idle
//
// start: SCL ~~~~~~~~~~\____
// SDA ~~~~~~~~\______
// x | A | B | C | D | i
//
// repstart SCL ____/~~~~\___
// SDA __/~~~\______
// x | A | B | C | D | i
//
// stop SCL ____/~~~~~~~~
// SDA ==\____/~~~~~
// x | A | B | C | D | i
//
//- write SCL ____/~~~~\____
// SDA ==X=========X=
// x | A | B | C | D | i
//
//- read SCL ____/~~~~\____
// SDA XXXX=====XXXX
// x | A | B | C | D | i
//
// Timing: Normal mode Fast mode
///////////////////////////////////////////////////////////////////////
// Fscl 100KHz 400KHz
// Th_scl 4.0us 0.6us High period of SCL
// Tl_scl 4.7us 1.3us Low period of SCL
// Tsu:sta 4.7us 0.6us setup time for a repeated start condition
// Tsu:sto 4.0us 0.6us setup time for a stop conditon
// Tbuf 4.7us 1.3us Bus free time between a stop and start condition
//
// synopsys translate_off
`include "timescale.v"
// synopsys translate_on
`include "i2c_master_defines.v"
module i2c_master_bit_ctrl(
clk, rst, nReset,
clk_cnt, ena, cmd, cmd_ack, busy, al, din, dout,
scl_i, scl_o, scl_oen, sda_i, sda_o, sda_oen
);
//
// inputs & outputs
//
input clk;
input rst;
input nReset;
input ena; // core enable signal
input [15:0] clk_cnt; // clock prescale value
input [3:0] cmd;
output cmd_ack; // command complete acknowledge
reg cmd_ack;
output busy; // i2c bus busy
reg busy;
output al; // i2c bus arbitration lost
reg al;
input din;
output dout;
reg dout;
// I2C lines
input scl_i; // i2c clock line input
output scl_o; // i2c clock line output
output scl_oen; // i2c clock line output enable (active low)
reg scl_oen;
input sda_i; // i2c data line input
output sda_o; // i2c data line output
output sda_oen; // i2c data line output enable (active low)
reg sda_oen;
//
// variable declarations
//
reg sSCL, sSDA; // synchronized SCL and SDA inputs
reg dscl_oen; // delayed scl_oen
reg sda_chk; // check SDA output (Multi-master arbitration)
reg clk_en; // clock generation signals
wire slave_wait;
// reg [15:0] cnt = clk_cnt; // clock divider counter (simulation)
reg [15:0] cnt; // clock divider counter (synthesis)
// state machine variable
reg [16:0] c_state; // synopsys enum_state
//
// module body
//
// whenever the slave is not ready it can delay the cycle by pulling SCL low
// delay scl_oen
always @(posedge clk)
dscl_oen <= #1 scl_oen;
assign slave_wait = dscl_oen && !sSCL;
// generate clk enable signal
always @(posedge clk or negedge nReset)
if(~nReset)
begin
cnt <= #1 16'h0;
clk_en <= #1 1'b1;
end
else if (rst)
begin
cnt <= #1 16'h0;
clk_en <= #1 1'b1;
end
else if ( ~|cnt || ~ena)
if (~slave_wait)
begin
cnt <= #1 clk_cnt;
clk_en <= #1 1'b1;
end
else
begin
cnt <= #1 cnt;
clk_en <= #1 1'b0;
end
else
begin
cnt <= #1 cnt - 16'h1;
clk_en <= #1 1'b0;
end
// generate bus status controller
reg dSCL, dSDA;
reg sta_condition;
reg sto_condition;
// synchronize SCL and SDA inputs
// reduce metastability risc
always @(posedge clk or negedge nReset)
if (~nReset)
begin
sSCL <= #1 1'b1;
sSDA <= #1 1'b1;
dSCL <= #1 1'b1;
dSDA <= #1 1'b1;
end
else if (rst)
begin
sSCL <= #1 1'b1;
sSDA <= #1 1'b1;
dSCL <= #1 1'b1;
dSDA <= #1 1'b1;
end
else
begin
sSCL <= #1 scl_i;
sSDA <= #1 sda_i;
dSCL <= #1 sSCL;
dSDA <= #1 sSDA;
end
// detect start condition => detect falling edge on SDA while SCL is high
// detect stop condition => detect rising edge on SDA while SCL is high
always @(posedge clk or negedge nReset)
if (~nReset)
begin
sta_condition <= #1 1'b0;
sto_condition <= #1 1'b0;
end
else if (rst)
begin
sta_condition <= #1 1'b0;
sto_condition <= #1 1'b0;
end
else
begin
sta_condition <= #1 ~sSDA & dSDA & sSCL;
sto_condition <= #1 sSDA & ~dSDA & sSCL;
end
// generate i2c bus busy signal
always @(posedge clk or negedge nReset)
if(!nReset)
busy <= #1 1'b0;
else if (rst)
busy <= #1 1'b0;
else
busy <= #1 (sta_condition | busy) & ~sto_condition;
// generate arbitration lost signal
// aribitration lost when:
// 1) master drives SDA high, but the i2c bus is low
// 2) stop detected while not requested
reg cmd_stop;
always @(posedge clk or negedge nReset)
if (~nReset)
cmd_stop <= #1 1'b0;
else if (rst)
cmd_stop <= #1 1'b0;
else if (clk_en)
cmd_stop <= #1 cmd == `I2C_CMD_STOP;
always @(posedge clk or negedge nReset)
if (~nReset)
al <= #1 1'b0;
else if (rst)
al <= #1 1'b0;
else
al <= #1 (sda_chk & ~sSDA & sda_oen) | (|c_state & sto_condition & ~cmd_stop);
// generate dout signal (store SDA on rising edge of SCL)
always @(posedge clk)
if(sSCL & ~dSCL)
dout <= #1 sSDA;
// generate statemachine
// nxt_state decoder
parameter [16:0] idle = 17'b0_0000_0000_0000_0000;
parameter [16:0] start_a = 17'b0_0000_0000_0000_0001;
parameter [16:0] start_b = 17'b0_0000_0000_0000_0010;
parameter [16:0] start_c = 17'b0_0000_0000_0000_0100;
parameter [16:0] start_d = 17'b0_0000_0000_0000_1000;
parameter [16:0] start_e = 17'b0_0000_0000_0001_0000;
parameter [16:0] stop_a = 17'b0_0000_0000_0010_0000;
parameter [16:0] stop_b = 17'b0_0000_0000_0100_0000;
parameter [16:0] stop_c = 17'b0_0000_0000_1000_0000;
parameter [16:0] stop_d = 17'b0_0000_0001_0000_0000;
parameter [16:0] rd_a = 17'b0_0000_0010_0000_0000;
parameter [16:0] rd_b = 17'b0_0000_0100_0000_0000;
parameter [16:0] rd_c = 17'b0_0000_1000_0000_0000;
parameter [16:0] rd_d = 17'b0_0001_0000_0000_0000;
parameter [16:0] wr_a = 17'b0_0010_0000_0000_0000;
parameter [16:0] wr_b = 17'b0_0100_0000_0000_0000;
parameter [16:0] wr_c = 17'b0_1000_0000_0000_0000;
parameter [16:0] wr_d = 17'b1_0000_0000_0000_0000;
always @(posedge clk or negedge nReset)
if (!nReset)
begin
c_state <= #1 idle;
cmd_ack <= #1 1'b0;
scl_oen <= #1 1'b1;
sda_oen <= #1 1'b1;
sda_chk <= #1 1'b0;
end
else if (rst | al)
begin
c_state <= #1 idle;
cmd_ack <= #1 1'b0;
scl_oen <= #1 1'b1;
sda_oen <= #1 1'b1;
sda_chk <= #1 1'b0;
end
else
begin
cmd_ack <= #1 1'b0; // default no command acknowledge + assert cmd_ack only 1clk cycle
if (clk_en)
case (c_state) // synopsys full_case parallel_case
// idle state
idle:
begin
case (cmd) // synopsys full_case parallel_case
`I2C_CMD_START:
c_state <= #1 start_a;
`I2C_CMD_STOP:
c_state <= #1 stop_a;
`I2C_CMD_WRITE:
c_state <= #1 wr_a;
`I2C_CMD_READ:
c_state <= #1 rd_a;
default:
c_state <= #1 idle;
endcase
scl_oen <= #1 scl_oen; // keep SCL in same state
sda_oen <= #1 sda_oen; // keep SDA in same state
sda_chk <= #1 1'b0; // don't check SDA output
end
// start
start_a:
begin
c_state <= #1 start_b;
scl_oen <= #1 scl_oen; // keep SCL in same state
sda_oen <= #1 1'b1; // set SDA high
sda_chk <= #1 1'b0; // don't check SDA output
end
start_b:
begin
c_state <= #1 start_c;
scl_oen <= #1 1'b1; // set SCL high
sda_oen <= #1 1'b1; // keep SDA high
sda_chk <= #1 1'b0; // don't check SDA output
end
start_c:
begin
c_state <= #1 start_d;
scl_oen <= #1 1'b1; // keep SCL high
sda_oen <= #1 1'b0; // set SDA low
sda_chk <= #1 1'b0; // don't check SDA output
end
start_d:
begin
c_state <= #1 start_e;
scl_oen <= #1 1'b1; // keep SCL high
sda_oen <= #1 1'b0; // keep SDA low
sda_chk <= #1 1'b0; // don't check SDA output
end
start_e:
begin
c_state <= #1 idle;
cmd_ack <= #1 1'b1;
scl_oen <= #1 1'b0; // set SCL low
sda_oen <= #1 1'b0; // keep SDA low
sda_chk <= #1 1'b0; // don't check SDA output
end
// stop
stop_a:
begin
c_state <= #1 stop_b;
scl_oen <= #1 1'b0; // keep SCL low
sda_oen <= #1 1'b0; // set SDA low
sda_chk <= #1 1'b0; // don't check SDA output
end
stop_b:
begin
c_state <= #1 stop_c;
scl_oen <= #1 1'b1; // set SCL high
sda_oen <= #1 1'b0; // keep SDA low
sda_chk <= #1 1'b0; // don't check SDA output
end
stop_c:
begin
c_state <= #1 stop_d;
scl_oen <= #1 1'b1; // keep SCL high
sda_oen <= #1 1'b0; // keep SDA low
sda_chk <= #1 1'b0; // don't check SDA output
end
stop_d:
begin
c_state <= #1 idle;
cmd_ack <= #1 1'b1;
scl_oen <= #1 1'b1; // keep SCL high
sda_oen <= #1 1'b1; // set SDA high
sda_chk <= #1 1'b0; // don't check SDA output
end
// read
rd_a:
begin
c_state <= #1 rd_b;
scl_oen <= #1 1'b0; // keep SCL low
sda_oen <= #1 1'b1; // tri-state SDA
sda_chk <= #1 1'b0; // don't check SDA output
end
rd_b:
begin
c_state <= #1 rd_c;
scl_oen <= #1 1'b1; // set SCL high
sda_oen <= #1 1'b1; // keep SDA tri-stated
sda_chk <= #1 1'b0; // don't check SDA output
end
rd_c:
begin
c_state <= #1 rd_d;
scl_oen <= #1 1'b1; // keep SCL high
sda_oen <= #1 1'b1; // keep SDA tri-stated
sda_chk <= #1 1'b0; // don't check SDA output
end
rd_d:
begin
c_state <= #1 idle;
cmd_ack <= #1 1'b1;
scl_oen <= #1 1'b0; // set SCL low
sda_oen <= #1 1'b1; // keep SDA tri-stated
sda_chk <= #1 1'b0; // don't check SDA output
end
// write
wr_a:
begin
c_state <= #1 wr_b;
scl_oen <= #1 1'b0; // keep SCL low
sda_oen <= #1 din; // set SDA
sda_chk <= #1 1'b0; // don't check SDA output (SCL low)
end
wr_b:
begin
c_state <= #1 wr_c;
scl_oen <= #1 1'b1; // set SCL high
sda_oen <= #1 din; // keep SDA
sda_chk <= #1 1'b1; // check SDA output
end
wr_c:
begin
c_state <= #1 wr_d;
scl_oen <= #1 1'b1; // keep SCL high
sda_oen <= #1 din;
sda_chk <= #1 1'b1; // check SDA output
end
wr_d:
begin
c_state <= #1 idle;
cmd_ack <= #1 1'b1;
scl_oen <= #1 1'b0; // set SCL low
sda_oen <= #1 din;
sda_chk <= #1 1'b0; // don't check SDA output (SCL low)
end
endcase
end
// assign scl and sda output (always gnd)
assign scl_o = 1'b0;
assign sda_o = 1'b0;
endmodule

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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 1.7 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
end
endmodule

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/////////////////////////////////////////////////////////////////////
//// ////
//// WISHBONE rev.B2 compliant I2C Master controller defines ////
//// ////
//// ////
//// 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_defines.v,v 1.3 2001/11/05 11:59:25 rherveille Exp $
//
// $Date: 2001/11/05 11:59:25 $
// $Revision: 1.3 $
// $Author: rherveille $
// $Locker: $
// $State: Exp $
//
// Change History:
// $Log: i2c_master_defines.v,v $
// 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.
//
// I2C registers wishbone addresses
// bitcontroller states
`define I2C_CMD_NOP 4'b0000
`define I2C_CMD_START 4'b0001
`define I2C_CMD_STOP 4'b0010
`define I2C_CMD_WRITE 4'b0100
`define I2C_CMD_READ 4'b1000

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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 1.11 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

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`timescale 1ns / 10ps