usb1_pe.v

usb1.1 ip核

/////////////////////////////////////////////////////////////////////
////                                                             ////
////  Protocol Engine                                            ////
////  Performs automatic protocol functions                      ////
////                                                             ////
////  Author: Rudolf Usselmann                                   ////
////          [e-mail]                                      ////
////                                                             ////
////                                                             ////
////  Downloaded from: http://www.opencores.org/cores/usb1_funct/////
////                                                             ////
/////////////////////////////////////////////////////////////////////
////                                                             ////
//// Copyright (C) 2000-2002 Rudolf Usselmann                    ////
////                         www.asics.ws                        ////
////                         [e-mail]                       ////
////                                                             ////
//// 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: usb1_pe.v,v 1.1.1.1 2002/09/19 12:07:24 rudi Exp $
//
//  $Date: 2002/09/19 12:07:24 $
//  $Revision: 1.1.1.1 $
//  $Author: rudi $
//  $Locker:  $
//  $State: Exp $
//
// Change History:
//               $Log: usb1_pe.v,v $
//               Revision 1.1.1.1  2002/09/19 12:07:24  rudi
//               Initial Checkin
//
//
//
//
//
//
//

`include "usb1_defines.v"

module usb1_pe(	clk, rst,

		// UTMI Interfaces
		tx_valid, rx_active,//pe也需要这两个信号的，从外壳引脚上获得

		// PID Information
		pid_OUT, pid_IN, pid_SOF, pid_SETUP,
		pid_DATA0, pid_DATA1, pid_DATA2, pid_MDATA,
		pid_ACK, pid_PING,

		// Token Information
		token_valid, //来自包拆装模块，说明是令牌包或握手ack包

		// Receive Data Output
		rx_data_done, crc16_err,//均来自包拆装模块

		// Packet Assembler Interface
		send_token, token_pid_sel,
		data_pid_sel,

		// IDMA Interface
		rx_dma_en, tx_dma_en,
		abort,
		idma_done,

		// Register File Interface，目前这个给我的感觉很不熟悉

		fsel,
		ep_sel, match, nse_err,
		ep_full, ep_empty,

		int_upid_set, int_crc16_set, int_to_set, int_seqerr_set,
		csr,
		send_stall//这可是输入啊

		);

input		clk, rst;
input		tx_valid, rx_active;//应该都是连在外壳引脚

// Packet Disassembler Interface
		// Decoded PIDs (used when token_valid is asserted)
input		pid_OUT, pid_IN, pid_SOF, pid_SETUP;
input		pid_DATA0, pid_DATA1, pid_DATA2, pid_MDATA;
input		pid_ACK, pid_PING;

input		token_valid;		// Token is valid，零牌包或是握手ack包

input		rx_data_done;		// Indicates end of a transfer，从包拆装获得
input		crc16_err;		// Data packet CRC 16 error

// Packet Assembler Interface
output		send_token;
output	[1:0]	token_pid_sel;
output	[1:0]	data_pid_sel;

// IDMA Interface
output		rx_dma_en;	// Allows the data to be stored
output		tx_dma_en;	// Allows for data to be retrieved
output		abort;		// Abort Transfer (time_out, crc_err or rx_error)
input		idma_done;	// DMA is done indicator

input		ep_full;	// Indicates the endpoints fifo is full
input		ep_empty;	// Indicates the endpoints fifo is empty

// Register File interface
input		fsel;		// This function is selected，一位
input	[3:0]	ep_sel;		// Endpoint Number Input
input		match;		// Endpoint Matched，端点匹配
output		nse_err;	// no such endpoint error

output		int_upid_set;	// Set unsupported PID interrupt
output		int_crc16_set;	// Set CRC16 error interrupt
output		int_to_set;	// Set time out interrupt
output		int_seqerr_set;	// Set PID sequence error interrupt

input	[13:0]	csr;		// Internal CSR Output，注意14位

input		send_stall;	// Force sending a STALL during setup，这个信号要注意


///////////////////////////////////////////////////////////////////
//
// Local Wires and Registers
//

// tx token decoding，这个应该是给token_pid_sel的,全是用来组装握手包的
parameter	ACK   = 0,
		NACK  = 1,
		STALL = 2,
		NYET  = 3;

// State decoding
parameter	[9:0]	// synopsys enum state，一位热码
		IDLE	= 10'b000000_0001,
		TOKEN	= 10'b000000_0010,
		IN	= 10'b000000_0100,
		IN2	= 10'b000000_1000,
		OUT	= 10'b000001_0000,
		OUT2A	= 10'b000010_0000,
		OUT2B	= 10'b000100_0000,
		UPDATEW	= 10'b001000_0000,
		UPDATE	= 10'b010000_0000,
		UPDATE2	= 10'b100000_0000;//这个好象没什么印象

reg	[1:0]	token_pid_sel;
reg	[1:0]	token_pid_sel_d;
reg		send_token;
reg		send_token_d;
reg		rx_dma_en, tx_dma_en;
reg		int_seqerr_set_d;//是int_seqerr_set的什么东西
reg		int_seqerr_set;
reg		int_upid_set;

reg		match_r;//跟match的关系要注意

// Endpoint Decoding
wire		IN_ep, OUT_ep, CTRL_ep;		// Endpoint Types注意是wire型
wire		txfr_iso, txfr_bulk, txfr_int;	// Transfer Types

reg	[1:0]	uc_dpd;//全然不知这是什么，现在有点感觉了

// Buffer checks
reg	[9:0]	/* synopsys enum state */ state, next_state;
// synopsys state_vector state

// PID next and current decoders
reg	[1:0]	next_dpid;
reg	[1:0]	this_dpid;
reg		pid_seq_err;//要注意它的用途，跟int_seqerr_set相区别，int_seqerr_set是用来输出的
wire	[1:0]	tr_fr_d;//干什么的？Number of transfers per micro-frame

wire	[13:0]	size_next;//14位：好象就没用过？
wire		buf_smaller;//好象也没用过

// After sending Data in response to an IN token from host, the
// host must reply with an ack. The host has XXXnS to reply.
// "rx_ack_to" indicates when this time has expired.
// rx_ack_to_clr, clears the timer
reg		rx_ack_to_clr;
reg		rx_ack_to_clr_d;
reg		rx_ack_to;
reg	[7:0]	rx_ack_to_cnt;//计数空间

// After sending a OUT token the host must send a data packet.
// The host has XX nS to send the packet. "tx_data_to" indicates
// when this time has expired.
// tx_data_to_clr, clears the timer
wire		tx_data_to_clr;
reg		tx_data_to;
reg	[7:0]	tx_data_to_cnt;

wire	[7:0]	rx_ack_to_val, tx_data_to_val;//注意是wire型


wire	[1:0]	next_bsel;//这是什么,好象也没有用过
reg		uc_stat_set_d;//指示要不要data0,data1变化的
reg		uc_dpd_set;//？是允许改变epN_dpid的标志，上面有个uc_dpd

reg		in_token;//输入令牌
reg		out_token;//输出令牌
reg		setup_token;//setup令牌

wire		in_op, out_op;	// Indicate a IN or OUT operation，应该是相对主机说的

reg	[1:0]	allow_pid;

reg		nse_err;
reg		abort;

wire	[1:0]	ep_type, txfr_type;//两位可以表达清楚了,txfr_type:txfr_iso,txfr_int,txfr_bulk
                                   //ep_type:IN_ep,OUT_ep,CTRL_ep
///////////////////////////////////////////////////////////////////
//
// Misc Logic
//

// Endpoint/CSR Decoding
assign IN_ep   = csr[9];//都是wire型，要注意
assign OUT_ep  = csr[10];
assign CTRL_ep = csr[11];

assign txfr_iso  = csr[12];//wire型
assign txfr_bulk = csr[13];
assign txfr_int = !csr[12] & !csr[13];//不是同步也不是批量，则是中断传输

assign ep_type = csr[10:9];//233行定义，也是wire型，00就是控制端点
assign txfr_type = csr[13:12];//与245，246，247呼应了，也是wire型

always @(posedge clk)
	match_r <= #1 match  & fsel;//fsel：This function is selected,一定搞清match怎么来的
                                //match是从外面输入的
// No Such Endpoint Indicator
always @(posedge clk)
	nse_err <= #1 token_valid & (pid_OUT | pid_IN | pid_SETUP) & !match;//是有效的令牌包，但是不匹配
                                                                       //则nse_err高
always @(posedge clk)
	send_token <= #1 send_token_d;//意料之中的事

always @(posedge clk)
	token_pid_sel <= #1 token_pid_sel_d;

///////////////////////////////////////////////////////////////////
//
// Data Pid Storage,数据包标识符存储
//

	reg	[1:0]	ep0_dpid, ep1_dpid, ep2_dpid, ep3_dpid;
reg	[1:0]	ep4_dpid, ep5_dpid, ep6_dpid, ep7_dpid;

always @(posedge clk or negedge rst)
	if(!rst)				ep0_dpid <= 2'b00;//复位用data0初始化
	else
	if(uc_dpd_set & (ep_sel == 4'h0))	ep0_dpid <= next_dpid;//uc_dpd_set是允许改变epN_dpid的标志

always @(posedge clk or negedge rst)
	if(!rst)				ep1_dpid <= 2'b00;
	else