?? usb_tx_phy.v
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/////////////////////////////////////////////////////////////////////
//// ////
//// USB 1.1 PHY ////
//// TX ////
//// ////
//// ////
//// Author: Rudolf Usselmann ////
//// rudi@asics.ws ////
//// ////
//// ////
//// Downloaded from: http://www.opencores.org/cores/usb_phy/ ////
//// ////
/////////////////////////////////////////////////////////////////////
//// ////
//// Copyright (C) 2000-2002 Rudolf Usselmann ////
//// www.asics.ws ////
//// rudi@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: usb_tx_phy.v,v 1.4 2004/10/19 09:29:07 rudi Exp $
//
// $Date: 2004/10/19 09:29:07 $
// $Revision: 1.4 $
// $Author: rudi $
// $Locker: $
// $State: Exp $
//
// Change History:
// $Log: usb_tx_phy.v,v $
// Revision 1.4 2004/10/19 09:29:07 rudi
// Fixed DPLL alignment in the rx_phy and bit stuffing errors in the tx_phy (if last bit bit was a stuff bit in a packet it was omitted).
//
// Revision 1.3 2003/10/21 05:58:41 rudi
// usb_rst is no longer or'ed with the incomming reset internally.
// Now usb_rst is simply an output, the application can decide how
// to utilize it.
//
// Revision 1.2 2003/10/19 17:40:13 rudi
// - Made core more robust against line noise
// - Added Error Checking and Reporting
// (See README.txt for more info)
//
// Revision 1.1.1.1 2002/09/16 14:27:02 rudi
// Created Directory Structure
//
//
//
//
//
//
//
`include "timescale.v"
`define USB_ASYNC_REST 1
module usb_tx_phy(
clk, rst, fs_ce, phy_mode,
// Transciever Interface
txdp, txdn, txoe,
// UTMI Interface
DataOut_i, TxValid_i, TxReady_o
);
input clk;
input rst;
input fs_ce;
input phy_mode;
output txdp, txdn, txoe;
input [7:0] DataOut_i;
input TxValid_i;
output TxReady_o;
///////////////////////////////////////////////////////////////////
//
// Local Wires and Registers
//
parameter IDLE = 3'd0,
SOP = 3'h1,
DATA = 3'h2,
EOP1 = 3'h3,
EOP2 = 3'h4,
WAIT = 3'h5;
reg TxReady_o;
reg [2:0] state, next_state;
reg tx_ready_d;
reg ld_sop_d;
reg ld_data_d;
reg ld_eop_d;
reg tx_ip;
reg tx_ip_sync;
reg [2:0] bit_cnt;
reg [7:0] hold_reg;
reg [7:0] hold_reg_d;
reg sd_raw_o;
wire hold;
reg data_done;
reg sft_done;
reg sft_done_r;
wire sft_done_e;
reg ld_data;
wire eop_done;
reg [2:0] one_cnt;
wire stuff;
reg sd_bs_o;
reg sd_nrzi_o;
reg append_eop;
reg append_eop_sync1;
reg append_eop_sync2;
reg append_eop_sync3;
reg append_eop_sync4;
reg txdp, txdn;
reg txoe_r1, txoe_r2;
reg txoe;
///////////////////////////////////////////////////////////////////
//
// Misc Logic
//
`ifdef USB_ASYNC_REST
always @(posedge clk or negedge rst)
`else
always @(posedge clk)
`endif
if(!rst) TxReady_o <= 1'b0;
else TxReady_o <= tx_ready_d & TxValid_i;
always @(posedge clk) ld_data <= ld_data_d;
///////////////////////////////////////////////////////////////////
//
// Transmit in progress indicator
//
`ifdef USB_ASYNC_REST
always @(posedge clk or negedge rst)
`else
always @(posedge clk)
`endif
if(!rst) tx_ip <= 1'b0;
else
if(ld_sop_d) tx_ip <= 1'b1;
else
if(eop_done) tx_ip <= 1'b0;
`ifdef USB_ASYNC_REST
always @(posedge clk or negedge rst)
`else
always @(posedge clk)
`endif
if(!rst) tx_ip_sync <= 1'b0;
else
if(fs_ce) tx_ip_sync <= tx_ip;
// data_done helps us to catch cases where TxValid drops due to
// packet end and then gets re-asserted as a new packet starts.
// We might not see this because we are still transmitting.
// data_done should solve those cases ...
`ifdef USB_ASYNC_REST
always @(posedge clk or negedge rst)
`else
always @(posedge clk)
`endif
if(!rst) data_done <= 1'b0;
else
if(TxValid_i && ! tx_ip) data_done <= 1'b1;
else
if(!TxValid_i) data_done <= 1'b0;
///////////////////////////////////////////////////////////////////
//
// Shift Register
//
`ifdef USB_ASYNC_REST
always @(posedge clk or negedge rst)
`else
always @(posedge clk)
`endif
if(!rst) bit_cnt <= 3'h0;
else
if(!tx_ip_sync) bit_cnt <= 3'h0;
else
if(fs_ce && !hold) bit_cnt <= bit_cnt + 3'h1;
assign hold = stuff;
always @(posedge clk)
if(!tx_ip_sync) sd_raw_o <= 1'b0;
else
case(bit_cnt) // synopsys full_case parallel_case
3'h0: sd_raw_o <= hold_reg_d[0];
3'h1: sd_raw_o <= hold_reg_d[1];
3'h2: sd_raw_o <= hold_reg_d[2];
3'h3: sd_raw_o <= hold_reg_d[3];
3'h4: sd_raw_o <= hold_reg_d[4];
3'h5: sd_raw_o <= hold_reg_d[5];
3'h6: sd_raw_o <= hold_reg_d[6];
3'h7: sd_raw_o <= hold_reg_d[7];
endcase
always @(posedge clk)
sft_done <= !hold & (bit_cnt == 3'h7);
always @(posedge clk)
sft_done_r <= sft_done;
assign sft_done_e = sft_done & !sft_done_r;
// Out Data Hold Register
always @(posedge clk)
if(ld_sop_d) hold_reg <= 8'h80;
else
if(ld_data) hold_reg <= DataOut_i;
always @(posedge clk) hold_reg_d <= hold_reg;
///////////////////////////////////////////////////////////////////
//
// Bit Stuffer
//
`ifdef USB_ASYNC_REST
always @(posedge clk or negedge rst)
`else
always @(posedge clk)
`endif
if(!rst) one_cnt <= 3'h0;
else
if(!tx_ip_sync) one_cnt <= 3'h0;
else
if(fs_ce)
begin
if(!sd_raw_o || stuff) one_cnt <= 3'h0;
else one_cnt <= one_cnt + 3'h1;
end
assign stuff = (one_cnt==3'h6);
`ifdef USB_ASYNC_REST
always @(posedge clk or negedge rst)
`else
always @(posedge clk)
`endif
if(!rst) sd_bs_o <= 1'h0;
else
if(fs_ce) sd_bs_o <= !tx_ip_sync ? 1'b0 : (stuff ? 1'b0 : sd_raw_o);
///////////////////////////////////////////////////////////////////
//
// NRZI Encoder
//
`ifdef USB_ASYNC_REST
always @(posedge clk or negedge rst)
`else
always @(posedge clk)
`endif
if(!rst) sd_nrzi_o <= 1'b1;
else
if(!tx_ip_sync || !txoe_r1) sd_nrzi_o <= 1'b1;
else
if(fs_ce) sd_nrzi_o <= sd_bs_o ? sd_nrzi_o : ~sd_nrzi_o;
///////////////////////////////////////////////////////////////////
//
// EOP append logic
//
`ifdef USB_ASYNC_REST
always @(posedge clk or negedge rst)
`else
always @(posedge clk)
`endif
if(!rst) append_eop <= 1'b0;
else
if(ld_eop_d) append_eop <= 1'b1;
else
if(append_eop_sync2) append_eop <= 1'b0;
`ifdef USB_ASYNC_REST
always @(posedge clk or negedge rst)
`else
always @(posedge clk)
`endif
if(!rst) append_eop_sync1 <= 1'b0;
else
if(fs_ce) append_eop_sync1 <= append_eop;
`ifdef USB_ASYNC_REST
always @(posedge clk or negedge rst)
`else
always @(posedge clk)
`endif
if(!rst) append_eop_sync2 <= 1'b0;
else
if(fs_ce) append_eop_sync2 <= append_eop_sync1;
`ifdef USB_ASYNC_REST
always @(posedge clk or negedge rst)
`else
always @(posedge clk)
`endif
if(!rst) append_eop_sync3 <= 1'b0;
else
if(fs_ce) append_eop_sync3 <= append_eop_sync2 |
(append_eop_sync3 & !append_eop_sync4); // Make sure always 2 bit wide
`ifdef USB_ASYNC_REST
always @(posedge clk or negedge rst)
`else
always @(posedge clk)
`endif
if(!rst) append_eop_sync4 <= 1'b0;
else
if(fs_ce) append_eop_sync4 <= append_eop_sync3;
assign eop_done = append_eop_sync3;
///////////////////////////////////////////////////////////////////
//
// Output Enable Logic
//
`ifdef USB_ASYNC_REST
always @(posedge clk or negedge rst)
`else
always @(posedge clk)
`endif
if(!rst) txoe_r1 <= 1'b0;
else
if(fs_ce) txoe_r1 <= tx_ip_sync;
`ifdef USB_ASYNC_REST
always @(posedge clk or negedge rst)
`else
always @(posedge clk)
`endif
if(!rst) txoe_r2 <= 1'b0;
else
if(fs_ce) txoe_r2 <= txoe_r1;
`ifdef USB_ASYNC_REST
always @(posedge clk or negedge rst)
`else
always @(posedge clk)
`endif
if(!rst) txoe <= 1'b1;
else
if(fs_ce) txoe <= !(txoe_r1 | txoe_r2);
///////////////////////////////////////////////////////////////////
//
// Output Registers
//
`ifdef USB_ASYNC_REST
always @(posedge clk or negedge rst)
`else
always @(posedge clk)
`endif
if(!rst) txdp <= 1'b1;
else
if(fs_ce) txdp <= phy_mode ?
(!append_eop_sync3 & sd_nrzi_o) :
sd_nrzi_o;
`ifdef USB_ASYNC_REST
always @(posedge clk or negedge rst)
`else
always @(posedge clk)
`endif
if(!rst) txdn <= 1'b0;
else
if(fs_ce) txdn <= phy_mode ?
(!append_eop_sync3 & ~sd_nrzi_o) :
append_eop_sync3;
///////////////////////////////////////////////////////////////////
//
// Tx Statemashine
//
`ifdef USB_ASYNC_REST
always @(posedge clk or negedge rst)
`else
always @(posedge clk)
`endif
if(!rst) state <= IDLE;
else state <= next_state;
always @(state or TxValid_i or data_done or sft_done_e or eop_done or fs_ce)
begin
next_state = state;
tx_ready_d = 1'b0;
ld_sop_d = 1'b0;
ld_data_d = 1'b0;
ld_eop_d = 1'b0;
case(state) // synopsys full_case parallel_case
IDLE:
if(TxValid_i)
begin
ld_sop_d = 1'b1;
next_state = SOP;
end
SOP:
if(sft_done_e)
begin
tx_ready_d = 1'b1;
ld_data_d = 1'b1;
next_state = DATA;
end
DATA:
begin
if(!data_done && sft_done_e)
begin
ld_eop_d = 1'b1;
next_state = EOP1;
end
if(data_done && sft_done_e)
begin
tx_ready_d = 1'b1;
ld_data_d = 1'b1;
end
end
EOP1:
if(eop_done) next_state = EOP2;
EOP2:
if(!eop_done && fs_ce) next_state = WAIT;
WAIT:
if(fs_ce) next_state = IDLE;
endcase
end
endmodule
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