Application Note Wing Poon Deon Roelofse Introduction networ
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Server Send Email Client Implementation with Ethernet Physical Layer
Application Note Wing Poon Deon Roelofse
Introduction
network device used refer electrical device connected network talking about, able communicate with other network devices through network protocols. Ethernet SX-Stack demo board. device driver distinct piece software consisting function calls variables that used network protocols control Ethernet controller network device. local used refer communications demo board network device software under discussion such local port local server. remote used refer physically removed network device communications thereof. Always used sense that communications between local remote device. also used distinguish remote port remote server from local one. server used refer software application network device such that offers network services such SMTP. client used refer software application network device such that uses services server. host used refer network device offering services application such email program. purposes terms host server means exactly same thing. Could also just refer application program either side communications channel, thus terms local remote host. Application Programmer's Interface. software functions variables application programmer utilize network communications network protocols. used transfer data over connection. connection used refer logical channel path communications between physically removed hosts applications. connection always certain state. connection closed open some other state. open connection also said established. Data only transferred between hosts when connection open established.
This Application Note describes implementation TCP/IP networking stack SX52BD communications controller. Ubicom created evaluation demonstrating Ubicom Internet connectivity networking stack. contains demonstration/evaluation board, source code, documentation use/customize stack using built-in Application Programming Interface (API). information setting running Ethernet SX-Stack demo board, please refer Ethernet SXStack Board User's Guide.
Quick Tutorial Internet Networking
transfer data between remote computers more commonly from applications computers applications remote computers over internet done with communication protocols. suite network communication protocols have been developed internet community there forever additions this list. Communication protocols sets rules that governs data transferred well should interpreted. Most network communication protocols defined documents called RFCs (Request Comments), example, RFC793 defines protocol. Network Communications Terminology Network protocols defined developed huge number different programmers organizations worldwide. There conflicting terms which workings networking communications described. Sometimes different terms used refer same thing. enormous amount confusion that sometimes caused, short list terms used this application note specific meaning thereof order: communications protocol rules communications pertaining specific protocol should handled interpreted. network protocols used refer collection communications protocols used perform network communications. Commonly called network device's TCP/IP stack.
Ubicomand Ubicom logo trademarks Ubicom, Inc. other trademarks mentioned this document property their respective componies.
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Server Send Email Client Implementation with Ethernet Physical Layer
octet used refer 8-bit quantity, commonly substituted "byte". Some processors have 32-bit bytes therefore term octet used RFCs avoid confusion. When this application note uses term byte, reference made 8-bit quantities used Ubicom controller. data bytes user application network protocol sends receives over connection. analogous payload missile. other material considered part necessities delivering payload. message also called data. header first number bytes ahead data bytes datagram, segment, message. header contains information described applicable protocol. data contained segment conveys information described applicable protocol's RFC. protocol used carrier another protocol, data interpreted according other protocol SMTP data carried protocol. segment used refer logical unit data. Almost universally used refer TCP. segment consists header data. data HTTP message SMTP data. datagram used refer complete block data. internet datagram consists header data. packet used refer block data physically transmitted over network. internet datagram handed network module transmit packet series packets, depending whether physical network send packets large datagram network cannot, fragments datagram into series packets which sent over network. packets reorganized receiving network node obtain original datagram. frame used exclusively refer packet transmitted Ethernet network. Commonly used when discussing Ethernet communications when only referring Ethernet protocol. socket used indicate unique logical address remote local connection's application. socket contains port number address. TCP/IP term "TCP/IP" commonly used whenever topic Internet communications discussed. Indeed, "TCP/IP" here refers whole suite networking protocols, with core building blocks being protocols. point keep mind here that TCP/IP used imply things first, more common interpretation, that collection standard networking protocols used communicating Internet, second, less common interpretation, that protocol protocol exclusively. Packet-Based Stream-Based Fundamentally, core, Internet packet-based network. Thus everything that flows through ultimately split into discrete packets, data head-
ers, which vary size. Often, application programmers prefer deal with stream-based data transfer mechanisms, which essentially open-ended form communication that amount data that transmitted non-finite. Stream-based mechanisms often have push-mechanism too, which `hurry' some section data along destination. protocol example packet-based protocol. example stream-based protocol. Knowing this will help determine which type network transport layer suitable your application Ethernet Ethernet shared-bus multiple-access with collisiondetection communication scheme. Ethernet defined broadly enough that supports several physical media types. media type used this implementation 10BaseT, commonly known twisted-pair. With Ethernet, important understand difference between logical node address physical node address. physical node address Ethernet guaranteed unique 48-bit number that assigned every Ethernet terminal interface manufactured. logical node address address that networking protocols when directing packets. allows many-to-one mapping physical addresses logical address. This essentially means that Ethernet controllers carry packets between different physical networks still deliver them only final destination. Internet world uses Address" logical addressing. This 32-bit number (commonly expressed "w.x.y.z"). addresses used segment internet into groups LANs each containing network devices. unique address each computer internet would impossible because huge volumes difficulty control assignments. Therefore, encounter different physical LANs that have same address. moment communication required from over internet, made gateway router that will behalf network device connected LAN. Ethernet best-attempt delivery network. other words, network will best deliver packet, once sent, destination. guaranteed delivery network, which means that additional software required ensure reliable packet delivery stream transport service. Furthermore, Ethernet does guarantee in-order delivery packets, once sent. Ethernet packet-switched network. term `frame' used refer packet data Ethernet. Ethernet frame must least bytes length, more than 1518 bytes. ensure data integrity (i.e. provide error-checking, error-correction), Ethernet frames constructed with 32-bit CRC. Ethernet interfaces, when receiving Ethernet frames, required check field discard (usually) frame should match.
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Ethernet SX-Stack think TCP/IP software being built four levels abstraction shown Figure 2-1.
specification independent logical addressing scheme used. delivery Ethernet frames specified exclusively Ethernet physical addresses. ARP, hence, bridge that maps addresses physical addresses. provides mechanism which node transmit packet destination, whose address that known, over Ethernet network. Datagrams datagram packet actual data combined with packet header. Internet communication travels form datagrams. They common mail pouches Internet world. Hence important understand role which described next.
Figure 2-1. Ethernet SX-Stack bottom, Physical layer, software that specific physical media being used transport packets (NIC Device Driver). Above this Internet layer, which implements protocols enable packets routed from node another Internet, well communications test diagnostic services (ARP, ICMP). next layer Transport protocols layer. This layer responsible end-to-end communication between application programs. protocols implemented this layer allow multiple connections established multiple application programs. These protocols regulate flow data, ensure data integrity, establish close-down connections (UDP, TCP). this point, layers discussed generally implemented Operating System running host. This that software developers need reinvent wheel when they need communicate information across network. Along these lines, stack provides same infrastructure thin, resourcescarce, embedded devices. Finally, capping stack, Applications layer. Software this level does need worry about mechanics information transported from machine Internet another. same time, applications guaranteed that whatever information they want communicate will transported over LANs WANs, including globe-spanning Internet. Application layer software implement standard services (e.g. DNS, FTP, SMTP, HTTP, etc.), they proprietary customized applications whose audience restricted same applications running other hosts. Address Resolution Protocol (ARP) allows dynamic mapping logical addresses physical addresses. discussed section 2.3, Ethernet physical interface supports unique 48-bit address. However, efficient routing packets, networks 32-bit logical address. This hierarchical addressing scheme allows individual nodes part subnet, which turn subsumed into larger subnet. Ethernet
Figure shows equivalent datagrams internet datagrams.
Figure 2-2. Datagrams
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Server Send Email Client Implementation with Ethernet Physical Layer
IP/ICMP stands Internet Protocol. common denominator entire TCP/IP suite protocols. protocol assumes unreliable, best-effort, connectionless packet delivery system, which exactly what Ethernet provides. describe each above terms more detail. unreliable, meant that sent packet guaranteed reach destination, even destination reachable. There several reasons packet reach destination: corrupted en-route discarded some point, destination node connected network. network routing tables were incorrect thus network does know deliver packet. Network congestion forced router somewhere en-route drop packet. Best-effort, means that network always tries best, given what knows, deliver packet. Connectionless, implies that there handshaking involved between sender recipient(s) prior packet being sent. Senders liberty send whenever they wish, subject course their getting time Ethernet, which shared-bus network. Packet, implies that data that traverses network have finite size, accompanied header. packets allowed fragmented network packet traverses network. However, SXStack does accept fragmented packets, since does packet reconstruction. DHCP Dynamic Host Configuration Protocol (DHCP) allows client-server paradigm host machines dynamically bootstrap, well configure, themselves when placed networked environment. Often used ability dynamically assign scarce addresses networked devices upon startup, DHCP however restricted that, capability configure server address, router address number vendor-specific configuration parameters. DHCP work, there must both client (such iSX) well server(s). client does need know address server, will discover itself. server(s) will offer address client request. Some servers allocate limited-time leases addresses, which means client will need periodically renew lease address. 2.10 User Datagram Protocol (UDP) allows applications send packets data across network each other. also used broadcast data multiple nodes. unreliable, connectionless delivery service (see section 2.7). packets lost network arrive order with other sent packets. However, packets checked data integrity; they
received, safe assume data contained within good. send packet destination application, source application must know both address destination host, well port number destination application. 2.11 Transmission Control Protocol (TCP) become protocol choice many applications because allows connection-based, reliable transport data across unreliable network. does this cost throughput, latency bandwidth utilization. Like UDP, achieves multiplexing through source destination ports. `connection' defined communication channel established between `end-points'. `end-point' defined unique combination both address port number. Before single byte data transmitted using TCP, connection between end-points. This typically done using three-way handshake involving transmission three segments. protocol takes care data sequencing, re-transmissions data-checking. important understand that HTTP messages SMTP data sent between applications remote network devices using transport service. HTTP messages SMTP data sent using nothing more than data bytes segment. important understand that based client-server paradigm. This does mean that transmits exclusively while other receives only. `client' application which initiates connection with `server'. achieve that, protocol allows server applications passive-open, which means listening that port accepting connections while allowing client applications active-open, which initiates connection. This current Ubicom TCP/IP stack software supports connections. Either connection established through passive-open active-open. 2.12 HTTP Hypertext Transfer Protocol used transfer images text browsers. browser contacts server such implemented Ethernet demo board. browser requests resources submits data using certain defined method information transfer. retrieve resources from server method "get". submit data program server method "post" "put". case "get" method, server will send requested resource such html file open connection browser. "post" method used submit data program server such found input fields some pages. data used control devices more commonly, generate html files send back browser such found internet "search engines" sending back results search.
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2.13 SMTP Simple Mail Transfer Protocol used send email SMTP server. sending program called send client. send client sends email recipient remote SMTP server receives email message. recipient will have retrieve email from mail server Post Office Protocol. SMTP protocol command response type protocol uses data carrier transport service.
segments sent over Ethernet requesting web-browser. RS232 port downloading content memory, RS232 port board used download content serial memory. voltage level converter that used change voltage levels from RS232 vice versa when communicating with RS232 port such serial port power supply, power supply board implemented with voltage regulator, associated components. supplies steady +5VDC components board. user expansion port, user port used interfacing daughter board each either output input pin. Java Virtual Machine port, JP5, Contact sales@ubicom.com further information. Sigma Delta Analog Digital Conversion circuit, R1,7,10, Sigma Delta conversion technique commonly used implement cost analog digital converters. circuit this case basically works alternating voltage between high Ubicom controller. This either charges discharges capacitor sensing capacitor's voltage level Ubicom controller through utilizing inherent voltage trip level input stage this pin, comparator implemented. output comparator used increment software result counter whenever comparator swings into state. Another software counter also incremented each swing comparator count number "conversions" certain number after which value result counter valid. conversion starts clearing counters. voltage level affected external influence which voltage divider feeding capacitor through R10. resistance thermistor changes with temperature will thus influence initial voltage level from which charged discharged. This means that time takes comparator swing over from other state either increased decreased result counter will counting higher lower according temperature thermistor. This effectively makes analog digital converter which result counter value representation temperature demo board software only displays value result counter dynamic page server demo does attempt translate this value real temperature value. Ubicom port programming Ubicom controller debugging code, Program debug tools currently from Parallax Advanced TransData plugged into JP2. single jumper connector, also included isolate res-
Ethernet Demo Board
3.0.1 Hardware Description Ethernet demo board connected 10/100BaseT Ethernet connection. describe board's Ethernet capability, simply consists controllers transformer, Ethernet controller, handles Ethernet communication over physical media while Ubicom controller, controls setup commanding Ethernet controller. Ubicom controller runs only program code named Ubicom Ethernet SX-Stack software board. stack software consists driver interface Ethernet controller various network protocols used communicate remote network devices over Ethernet. other components sections circuitry either supporting basic Ethernet components implement additional functionality board. more detailed description hardware demo board follows: Ubicom controller, Ubicom controller operates frequency 50MHz implemented with external resonator, controller executes instruction clock cycle, thus every 20ns. controller 4096 electrically erasable FLASH program memory bytes SRAM data memory. Ethernet physical layer controller, board connected 10/100BaseT Ethernet connection through Ethernet electrical signalling control interface Ubicom controller implemented Ethernet Controller, Ethernet controller interfaces Ubicom controller through ports Ubicom controller. Port bidirectional databus transfer 8-bit data from Ethernet controller. Port used address lines. SA0-4, read write signals complete interface Ethernet controller. Since Realtek Ethernet controller developed type plug-in cards, addressing control interface Ethernet controller according standard. Memory storing pages, server board implemented storing resources consisting html files graphics data serial EEPROM memory, Ubicom controller will request certain resource from remote browser Ethernet will retrieve applicable html file graphics content from serial memory serial implemented pins Ubicom controller. data then packaged into
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onator, from port during programming debugging.
Demo Programs
Server server implemented software exclusively using which explained "Using API". Ubicom Ethernet stack software supports simultaneous connections Ethernet SX-Stack demo board. connection remote server either initiated from demo board established from remote server initiating connection. server essentially passive device that waits requests from remote web-browsers. remote browser initiates connection demo board. Once demo board receives request establish connection, creates socket that consists remote port number remote address. connection manager function TCP/IP stack software demo board uses this socket recognize subsequent incoming datagrams from remote server running web-browser directs data from those packets application software using connection bound that socket. This means that another application using other connection receiving data from whole different remote server only data destined will delivered remote web-browser requests resources from demo board server asking very first text line HTTP message. HTTP message payload segment meaning that data section segment whole HTTP message. server supports types requests, also referred methods: method request text line looks something like this: /index.htm resource stored EEPROM memory under index.htm will then retrieved from memory, packaged into segments sent back requesting web-browser using information socket bound connection server. post post method request text line looks something like this: POST /postctrl.htm Normally, html file associated with post method will contain text input forms buttons that clicked send control values server. This means that before post text control values take place, web-browser will first html file display page with input controls. HTTP message containing post method line will sent server once user presses submit button page with controls. variable that known server used control variable control something like board will sent along with post request. Web-browsers different ways doing post request server. Some like Internet Explorer will send only HTTP message containing post
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text line variables. Web-browsers like Netscape Navigator sends seperate messages, each seperate segment. contains post method text line other contains variables. server demo demo board distinguishes between posts from these types browsers will still find control variables first following HTTP message. Once server sends resource, html file's text other graphics data, web-browser will close open connection connection manager demo board will delete socket that bound that open connection. Subsequent requests from server will result socket being created. reason open connection should closed immediately after successful data transfer conserve memory that taken storing sockets well prevent spurious packets internet cause false data transfers. resources serial EEPROM memory stored pure text data retrieved hash value that stored lookup table memory ahead actual content. Essentially, when data stored EEPROM, every resource's data-bytes were added together clipped byte value which handle hash that identifies resource. server application searches resource name post text line HTML message adds byte values resource name together this value corresponds handle hash value which stored serial memory when resources were transferred memory RS232 serial port. lookup table simply contains pointers into memory indicating starting addresses number bytes each resource. 4.1.1 Dynamic Pages serial EEPROM memory contains three dynamic pages: temperature.htm resources.htm postctrl.htm dynamic page contains content that changes according some external value parameter. simple example page that shows temperature sensor board. temperature degrees when page retrieved again. Ethernet SX-Stack demo board implements dynamic pages very easy understand manner. Dynamic pages stored serial EEPROM with special sequence data bytes characters embedded exact location where dynamic content needs inserted. Look temperature.htm file below: <HTML> <HEAD> <TITLE> Board Temperature Monitor </TITLE> </HEAD> <BODY BGCOLOR=#404040 text=#80FF00>
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<H2> Real-time Board Temperature Monitor </H2>
<center>Temperature now: <font color=#FF99FF> </font></center> <font color=#FFFFFF>Hit 'F5' click 'Refresh' button your browser current temperature</font> </BODY> </HTML> three characters indicated with bold text "magic key" that used indicate location dynamic content this page. this case value from analog digital converter needs inserted here when text this file resource being packaged into segment ready sent requesting web-browser. server software will look these three characters while retrieving data bytes from serial memory will replace them with value from analog digital converter. important note that magic needs non-printable characters that could never mistaken real text repeated elsewhere file. resources.htm file below also contains dynamic content which value page visited counter. magic same temperature.htm page. server software distinguishes which dynamic content belongs which dynamic webpages file also looking hash value requested resource. this case requested resource /resources.htm <HTML> <HEAD> <TITLE> Resource Usage </TITLE> </HEAD> <BODY BGCOLOR=#404040 text=#FF8000> <H2>Resource Usage:</H2> <CENTER> <TABLE border=2 bgcolor=#000000 width="50%"> <TR> width="30%">ROM</TD> align="center">2527</TD> </TR> <TR> width="30%">RAM</TD> align="center">98</TD> </TR> </TABLE> </CENTER> size=+2
This pages been accessed color=#FF99FF> </font> times. </BODY> </HTML> Finally, postctrl.htm page shown below. Only characters magic used here indicate requesting browser which graphic picture once been controlled using http post method. this case server software will always replace magic character with either after checking status LED. switched http post method, will send back this page with giving ledon.gif. page will thus display bright picture indicating that http post method request switch successful. <HTML> <HEAD><TITLE>Ubicom POST</TITLE></HEAD> control HTML <font size=+2
<BODY BGCOLOR=#404040 text=#80FF00> <H2> Remote control demo </H2> <FONT color=#FFFFFF>Control messages sent HTTP POST method. this devices such conditioners remotely switched from standard web-browser. <BR><BR>Select radio button click Submit control demo board.<BR><BR> LED<BR> <left><img <form method="POST">
<input type="radio" name="led" value="1"> On<input type="radio" name="led" value="0" CHECKED> Off<input type="radio" gle
</form> </FONT> </BODY> </HTML> name="led" value="t"> Tog-
<input type="submit" value="Submit">
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Send Email Client Send Email client also implemented using functions listed "Using API". server uses connection while connection used email client. email client differs from server sense that passively waiting request establish connection with remote server order transfer data segments. email client initiates opening connection with remote server that listening SMTP server. Listening refers half socket created remote server that contains only remote SMTP server's port number which universally assigned Once connection established between demo board's email client remote SMTP server, SMTP server will fill socket with demo board's address port number. demo board socket already fully defined before email client attempts establish connection with remote SMTP server. socket demo board contains address remote SMTP server port number local connection. before, incoming data from remote SMTP server will delivered send email client application which using connection send email user presses button demo board. This sets SMTP send state machine into motion. SMTP protocol command-response type protocol. sender, this case demo board, sends SMTP command segment remote SMTP server which will respond with response code applicable data bytes segment. Even though email client demo board commander during data transfers, first SMTP data sent from remote SMTP server email client directly after connection been established. This very first SMTP data serves identifier which contains something like following text: Eserv/2.92 ESMTP Server Ready. response code always sent first three characters. this case means "service ready". email client will identify itself sending SMTP command like this: HELO SMTP server respond with error code ready recognizing "sx" user with email account SMTP server, will respond with: Hello 10.1.1.20 response code means "Requested mail action completed". send email client will send packet containing: MAIL FROM: <sx> sender's email address name inserted between braces. sender valid SMTP server (you need email account SMTP server able send email) will respond with:
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send email client will send: RCPT <joe@demo.sx> This indicates recipient mail. SMTP server will accept this command email account there relay email another SMTP server that will deliver email joe. SMTP server will respond with: This indicates email client that SMTP server will accept mail. email client will send: DATA indicate that email data sent. SMTP server respond with text string which contains formatting instructions whatever needed custom implementation: send mail data, with This indicates send email client send mail data must with definite <CRLF>.<CRLF> since packets usually padded with extra data bytes that confused mail data. email client will send mail data follows segment: From: Subject: Button Pressed! Button Pressed!
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SMTP server indicate syntax error some other error code mail format wrong will respond with following mail data acceptable: message accepted delivery send email client will indicate SMTP server nothing more with: QUIT
SMTP server will respond with following message other errors encountered: Service closing transmission channel Now, SMTP server will initiate closing connection established between demo board itself. This change command response roles SMTP protocol probably give large degree confidence email send client program that SMTP server indeed alive during whole mail transfer very when transmission channel closed.
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TCP/IP Stack Software
SX_ETH_ADDR0-5 Ethernet controller, U5's address This 48-bit Ethernet address Media Access Controller address which will used Ethernet controller when sending listening Ethernet frames. demo board uses address that used only temporary. change this need assign address. INT_PERIOD This value from that subtracted from free-running hardware counter that causes interrupt when overflows. interrupt routine called response overflowing counter currently stack uses interrupt routine advance various software counters well flash read value temperature sensor. value INT_PERIOD subtracted from counter's value when return from interrupt instruction executed interrupt routine. This ensures known interrupt frequency with jitter. frequency which interrupt routine called easily determined dividing Ubicom controller, U2's clock frequency number INT_PERIOD. Since hardware timer advances once every cycle calculation simple divide. important note that various state machines used stack (TCP/UDP/SMTP) execute fast possible. They implemented with virtual peripheral type code such other Ubicom virtual peripheral software. Virtual peripheral software always inside interrupt routine thus executed periodically. stack's state machines inside interrupt routine. They mainline loop code such following code will explain: main: state machines code :main
TCP/IP stack software consists three API's which programmer use: SMTP Since there only Ethernet controller board, board have address Ethernet address (also referred address). Every Ethernet controller unique address since electrical signalling done these devices. following variables before stack used: myIP3-0 board's address Typically could have: myIP3 myIP2 myIP1 myIP0 giving demo board address 10.1.1.20
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Server Send Email Client Implementation with Ethernet Physical Layer
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Using
only transmit data once connection established open. Incoming data delivered correct application with flag called TCP_SOCK. state machine sets this flag when incoming internet datagram application using connection clears when incoming datagram application using connection every function (except TCPApp1Init TCPApp2Init), there piece code that checks this flag will jump label under either space where connection application code goes where connection application code goes. your application used TCPApp1Init must insert your code functions under label indicated connection vice versa. transmission data. Each connection same priority transmit therefore each pass through functions called state machine alternated between connection every function (except TCPApp1Init TCPApp2Init), there piece code that checks flag called TCP_TXSEMA will jump label under either space where connection application code goes where connection application code goes. your application used TCPApp1Init must insert your code functions under label indicated connection vice versa. TCP_TXSEMA flag alternated inside main loop code TCP/IP stack software. Establishing connection description logical sequence steps will need take establish connection follows: will need have stack variables such described under 5.0. They board's address address Ethernet controller. There functions available, each connection. They are: TCPApp1Init Only used doing active open. TCPApp2Init Only used doing passive open. These functions called continuously long connection state closed. these functions will insert "trigger code" that will start passive open active open response some trigger. will also define sockets here. example trigger code continuously check whether switch pressed once pressed, have active open done send email. Passive open code will more than often just definition socket since trigger open connection will from remote TCP. example doing passive open TCPApp2Init shown below:
collection functions which state machine calls variables that used state machine. must think typical interrupt routine programming language used programmer. programmer that wants execute code inside interrupt routine function, let's advance counter check switch pressed, doesn't need call interrupt routine. interrupt routine automatically called response event periodically called response hardware timer's value. state machine calls certain functions when events occur such incoming data that available. also calls other functions periodically like check application such send email client wants open connection. programmer using never call function directly would rather simply insert your code space where function called. Your code will executed once applicable event occurs will executed periodically. Before look example API, note following: There connections available this TCP/IP stack. applications cannot share connection since connection defined socket that describes only remote connection. connection only used active open. connection only used passive open. Your application software either open connection remote server referred "active open" initiating connection, your software "passive open" waiting remote server initiate connection. server case "passive open" send email client uses "active open". active open need specify address remote server wish establish connection with port number application wish connect with. passive open need specify local port your application will use. connection manager will "listen" this port incoming segments from remote servers wishing establish connection with your application software. short discussion connections handled order now. prevent overrun receive buffer Ethernet controller possible resulting dropped frames, main loop TCP/IP stack software gives precedence reception internet datagrams opposed transmission internet datagrams. This means that software will continue handling incoming internet datagrams whatever protocols until there more datagrams receive buffer Ethernet controller. Once receive buffer empty will call necessary functions check application wants transmit something. case state machine, your application
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************** _TCPApp2Init Called repeatedly long connection2 state closed [TCP Function] INPUT: none OUTPUT: none ************** _bank TCB2_BANK tcb2LocalPortLSB, #HTTP_PORT_LSB tcb2LocalPortMSB, #HTTP_PORT_MSB bank HTTP_BANK httpParseState httpURIHash indicate tcp2 connection setb flags2.TCP_SOCK @TCPAppPassiveOpen retp Looking code excerpt local port that will listening being tcb2LocalPortLSB tcb2LocalPortMSB. this case value declared elsewhere used which worldwide standard port number server listens requests from browsers. http variables cleared which needed initialize http protocol. last section code where flag flags2 variable indicate state machine using connection Finally jump made function called TCPAppPassiveOpen. This function will start state machine putting into "Listening" state. Note that since connection state closed more "listen", TCPApp2Init will called again from main loop. Only when another function named TCPAppClose called, will connection state reset closed will TCPAppPassiveOpen called again. When trigger code however, would jump over call TCPAppPassiveOpen will only allow this function called once trigger made "web server enable" push button board. will look TCPApp1Init function active open.
************** _TCPApp1Init Called repeatedly long connection1 state closed [TCP Function] INPUT: none OUTPUT: none ************** trigger code test switch retp exit, switch pressed _bank SMTP_BANK #SMTP_CONNECT start SMTP state machine connect smtpState, local remote ports tcp1 connection _bank TCB1_BANK tcb1LocalPortLSB, #100 tcb1LocalPortMSB, #100 tcb1RemotePortLSB, #SMTP_PORT_LSB tcb1RemotePortMSB, #SMTP_PORT_MSB fill remote connect with socket _bank TCPSOCKET_BANK sock1RemoteIP3,#SMTP_SERVER_IP3 sock1RemoteIP2,#SMTP_SERVER_IP2 sock1RemoteIP1,#SMTP_SERVER_IP1 sock1RemoteIP0,#SMTP_SERVER_IP0 indicate tcp1 connection clrb flags2.TCP_SOCK @TCPAppActiveOpen; open connection socket1 retp trigger code function checks state switch variable will keep exiting function until switch pressed. SMTP code inserted here used start SMTP state machine once switch pressed. Note setup socket this connection. local port used email application with tcb1LocalPortLSB
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tcb1LocalPortMSB. remote port email client must contact tcb1RemotePortLSB tcb1RemotePortMSB. this case value defined elsewhere used which worldwide standard port number SMTP servers listen incoming connections. Finally, remote SMTP server's address wish contact sock1RemoteIP3-0. Note clearing flags2 indicate connection state machine then final jump function named TCPAppActiveOpen which will state machine into motion connect remote SMTP server. Also note that again, TCPApp1Init will called again from main loop since connection state connection transitioning from closed other states. Only when connection closed will TCPApp1Init called again trigger code will again block opening connection until switch pressed again. Note that only once connection established actual data transferred. During opening process, single byte data transmitted received your application. Handling incoming data sending data Once connection open there situations: data received from remote server connected send data remote server connected important realize again that there difference between segment data. segment contains header data. incoming segments, state machine strips header from segment only delivers data your application. outgoing segments, your application only hands data state machine once done, state machine will append header data send segment. incoming segment will cause receive event that state machine will call following functions following order: TCPAppRxBytes This function called only once after segment received. variable called tcpAppRxBytesMSB, contains value number data bytes segment contains. This value checked against expected bytes prepare counter. TCPAppRxData This function will called many times value tcpAppRxBytesMSB, represents. Note that data bytes passed here through working register. here where could parse store incoming data bytes. TCPAppRxDone This function called only once after last call TCPAppRxData. This handy since need counter TCPAppRxData know when last byte will delivered. Your application this function acknowledgement that
data been successfully received. Also, need make decision after reception data will insert your code here. previously said, main loop TCP/IP stack software gives precedence reception internet datagrams opposed transmission internet datagrams. This means that software will continue handling incoming internet datagrams whatever protocol until there more receive buffer Ethernet controller. Once receive buffer empty will call necessary functions check application wants transmit something. case state machine, your application only transmit data once connection established open. Once connection open, state machine will call following functions following order: TCPAppTxBytes This function called only once before rest functions shown below. this function your application must indicate many data bytes wants send. This done loading variables named tcpXUnAckMSB, with value indicating number bytes sent. Because there connections, each internet datagram containing segment stored separate transmit buffer Ethernet controller. This needed that segments re-sent they were acknowledged remote remote server connected with. tcpXUnAck variable needs replaced with depending which connection using. TCPAppTxData This function will called many times value tcpXUnAckMSB, represents. Each time function exits loads data byte working register into segment being constructed. Here pass data that wish transmit state machine. TCPAppTxDone This function called only once after last call TCPAppTxData. Your application this acknowledgement that data been sent. Also, need make decision after sending data would insert your code here. Note that this function called indicate that data been successfully delivered remote server. doesn't even mean that acknowledged remote TCP. outgoing internet datagram containing your data will loaded into transmit buffer Ethernet controller will re-transmitted every approximately every seconds until acknowledge received from remote TCP. There however timeout implemented stack which will cause connection close reset should there reply from remote about seconds after first transmission made.
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Using
Since connectionless protocol, packets sent fire forget fashion opposed which waits acknowledgment that segment indeed been received remote host. Note that this acknowledgement does mean that remote application received data segment. TCP/IP stack uses protocol state machines only connection-oriented protocols. state machine would typically start closed state transition through various states open state once connection established. could stay specific state until acknowledges received until connections open closed. Outgoing packets constructed sent immediately without waiting response from destination. Incoming packets handled function calls functions which insert your application code. commonly want following: Send data remote server Receive data from remote host Listening packets function named UDPAppInit called once never again when TCP/IP stack software starts executing. have specify local port number which listen incoming packets. function shown below: ************** UDPAppInit Application Initialization code (Example) This function called automatically once stack During startup [UDP Function] INPUT: none OUTPUT: none ************** _bank UDP_BANK udpRxDestPortMSB, #UDP_RX_DEST_MSB udpRxDestPortLSB, #UDP_RX_DEST_LSB retp
Handling incoming data sending data Whenever packet received listening port specified UDPAppInit, TCP/IP stack software calls following functions: UDPAppProcPktIn This function called only once when packet received. stack also receives packets that were sent broadcast mode, those packets handled other functions stack that part API. Therefore, UDPAppProcPktIn called stack when broadcast packet received. Broadcast packets commonly used DHCP protocol this stack. opposed state machine that calls TCPAppRxData many times there data bytes received segment pass data application, must call NICReadAgain which will each time called, retrieve data byte from received packet. databyte delivered working register. following variables also contains value number databytes received packet:udpRxDataLenMSB, LSB. remote port from which packet came indicated value variable called udpRxSrcPortMSB, LSB. respond immediately received packet calling UDPStartPktOut UDPAppProcPktIn. Before calling UDPStartPktOut, will have local port number from which will sending packet well remote port number will sending packet Since immediately responding packet, remote port number will available variable udpRxSrcPortMSB, LSB. local port udpTxSrcPortMSB, remote port udpTxDestPortMSB, LSB. will also have variable called udpTxDataLenMSB, which indicates number data bytes will transmitting packet. After call UDPStartPktOut load databytes into packet loading each databytes into working register calling NICWriteAgain after each load. Once databytes loaded must call UDPEndPktOut send packet. sequence described above shown below: **************
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Server Send Email Client Implementation with Ethernet Physical Layer
AN37
UDPAppProcPktIn Application Incoming packet handler (Example) This function called whenever application (matches udpRxDestPortxSB) packet received. NICReadAgain() extract appplication call
sequentially extract each byte <data> field packet. [UDP Function] INPUT: number bytes <data> <source_port> OUTPUT: none ************** call NICReadAgain_7 retrieve first databyte from packet #%01000000 toggle pins _bank UDP_BANK udpTxSrcPortMSB local port udpTxSrcPortLSB udpTxDestPortMSB, udpRxSrcPortMSB remote port (reply received packet) udpTxDestPortLSB, udpRxSrcPortLSB udpTxDataLenMSB, number databytes loaded into packet udpTxDataLenLSB, call UDPStartPktOut send port state, (set databyte no1) call NICWriteAgain_7 write databyte into packet #$00; one-byte padding, (set databyte no2) call NICWriteAgain_7 write databyte into packet call UDPEndPktOut retp
also above code statements custom function called from main loop need periodically transmit packets transmit packet response local hardware trigger such switch press. will however need variable called remoteIP3-0 with remote address remote server sending packet RemoteIP3-0 also used other protocols stack above code example remoteIP3-0 variable already with correct address remote server since replying immediately incoming packet. variable loaded TCP/IP stack software when packet received.
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Server Send Email Client Implementation with Ethernet Physical Layer
AN37
Using SMTP
send email client uses this domain name identify itself remote SMTP server. code shown below, domain name created email account demo board called board@acme.com, domain name will acme. ************** _senderDomainName Contains sender's domain name. [SMTP function] INPUT: none OUTPUT: none ************** SMTPTEXT_HELO 'HELO insert Domain name here 'sx' CR,LF SMTPTEXT_HELO_END _mailFrom SMTP state machine reads databytes stored here program words send email client uses this name sender. code below, sender's name board's email address created board@acme.com, sender's name would board. ************** _mailFrom Contains sender's name. [SMTP function] INPUT: none OUTPUT: none ************** SMTPTEXT_MAIL=$ dw'MAIL FROM: insert sender's name here dw'<sx>' dwCR,LF SMTPTEXT_MAIL_END=$
SMTP does consist function calls does API. SMTP uses carrier transport protocol send receive SMTP data. SMTP thus consists only pre-defined locations program memory where insert SMTP data. SMTP data commonly consists sender recipient email addresses, domain name email text. locations source file where SMTP data located indicated with assembler labels looking similar function definitions. When that SMTP "function" "called" will meaning that SMTP data located SMTP function will read SMTP state machine. SMTP state machine also called part overall application code called send email client. Using carrier SMTP data Before SMTP state machine read data stored SMTP locations, there established connection between demo board remote SMTP server. SMTP servers listen port number incoming connections. will therefore have insert "trigger code" TCPApp1Init establish connection with remote SMTP server. TCPApp2Init cannot used since only used passive open connection. Refer "Using API" example code using TCPApp1Init establish connection. Starting SMTP state machine SMTP state machine implemented send email client application code. application code inserted functions since SMTP uses data carrier. This means that incoming SMTP data will delivered SMTP state machine receive functions outgoing SMTP data will loaded from functions related transmission segments. SMTP state machine started loading variable called smtpState with value pre-defined SMTP_CONNECT. This must done TCPApp1Init since this function will called again once connection established. SMTP state machine does actually start anything until connection open. Once connection open, send email client will connect with remote SMTP server send email. Sending email Email commonly sent SMTP servers listening port This universally well-known port number setup setting SMTP_PORT_MSB SMTP_PORT_LSB value This changed using private SMTP server listening different port. following SMTP "functions" will "called" SMTP state machine once connection open state machine started: _SenderDomainName SMTP state machine reads databytes stored here program words
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Server Send Email Client Implementation with Ethernet Physical Layer
AN37
_mailTo SMTP state machine reads databytes stored here program words uses this email address recipient. code shown below, recipient's email address joe@demo.sx ************** _mailTo Contains recipient's email address. [SMTP function] INPUT: none OUTPUT: none ************** SMTPTEXT_RCPT=$ 'RCPT insert recipient's email address here '<joe@demo.sx>' CR,LF SMTPTEXT_RCPT_END=$ _mailData SMTP state machine reads databytes stored here program words uses this email message text that sent recipient. Standard fields interpreted email programs such Outlook Express commonly included email message. Some these fields "From:, Subject".
_mailData Contains mail message Data. [SMTP function] INPUT: none OUTPUT: none ************** SMTPTEXT_TEXT=$ 'From: CR,LF insert field here 'To: Joe' CR,LF insert Subject: field here 'Subject: Button Pressed!' CR,LF,CR,LF insert body email message here 'Button pressed' CR,LF,'.',CR,LF SMTPTEXT_TEXT_END=$
**************
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Server Send Email Client Implementation with Ethernet Physical Layer
AN37
Application Programming Interface (API)
Functions
9.1.1 UDPAppInit()
Application Initialization code. This function called automatically once stack during startup. INPUT: none OUTPUT: none
9.1.2 UDPAppProcPktIn()
Application Incoming packet handler. This function called whenever application (matches udpRxDestPortxSB) packet received. application call NICReadAgain() extract sequentially extract each byte <data> field packet. INPUT: number bytes <data> <source_port> OUTPUT: none
9.1.3 UDPStartPktOut()
Starts outgoing packet constructing packet header. INPUT: {remoteIP0-3} destination addr Source Port Destination Port Data Length (just data) OUTPUT: none
9.1.4 UDPEndPktOut()
Wraps transmits packet. INPUT: none OUTPUT: none
9.1.5 NICReadAgain()
Call this function extract, byte time, data encapsulated packet This function should called withinUDPAppProcPktIn(). INPUT: none OUTPUT: byte read
9.1.6 NICWriteAgain()
Call this function write, byte time, data sent packet.This function should called after callingUDPStartPktOut(), before calling UDPEndPktOut(). INPUT: byte written OUTPUT: none
Variables
9.2.1 remoteIP[3:0]
Destination address outgoing packet, well Source address incoming packet.
9.2.2 myIP[3:0]
Source address outgoing packet, well filter Destination address incoming packets. This usually tothe address assigned
9.2.3 UDPRxSrcPortMSB, UDPRxSrcPortLSB
Source Port number incoming packet.
9.2.4 UDPRxDestPortMSB, UDPRxDestPortLSB
Filter Destination Port number incoming packets.
9.2.5 UDPRxDataLenMSB, UDPRxDataLenLSB
Length, bytes, data field incoming packet.
9.2.6 UDPTxSrcPortMSB, UDPTxSrcPortLSB
Source Port number outgoing packet.
9.2.7 UDPTxDestPortMSB, UDPTxDestPortLSB
Destination Port number outgoing packet.
9.2.8 UDPTxDataLenMSB, UDPTxDataLenLSB
Length, bytes, data field incoming packet.
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Server Send Email Client Implementation with Ethernet Physical Layer
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Functions
9.3.1 TCPApp1Init()
application initialization code. Called repeatedly long connection state closed. INPUT: none OUTPUT: none
9.3.2 TCPApp2Init()
application initialization code. Called repeatedly long connection state closed. INPUT: none OUTPUT: none
9.3.3 TCPAppTxBytes()
Called before transmitting packet application data wishes send. application cannot send more than TCP_SEG_SIZE (1400) bytes INPUT: none OUTPUT: {tcp1UnAckMSB,tcp1UnAckLSB} number bytes transmit connection no.1 {tcp2UnAckMSB,tcp2UnAckLSB} number bytes transmit connection no.2
9.3.4 TCPAppRxBytes()
Indicator application that packet been received that TCPAppRxByte about called many times they bytes data. INPUT: number received data bytes OUTPUT: none
9.3.5 TCPAppTxData()
This routine called once each byte application says wishes transmit. INPUT: none OUTPUT: data byte transmit
9.3.6 TCPAppRxData()
Called once each byte received packet. INPUT: received data byte OUTPUT: none
9.3.7 TCPAppTxDone()
This called following last call TCPAppTxData(). signifies transmitted data successfully reached remote host. INPUT: none OUTPUT: none
9.3.8 TCPAppRxDone()
This called following last call TCPAppRxData(). signifies received packet. INPUT: none OUTPUT: none
9.3.9 TCPAppPassiveOpen()
passive open. example, listen connections given port. INPUT: {tcb1LocalPortMSB, tcb1LocalPortLSB} port listen connection {tcb2LocalPortMSB, tcb2LocalPortLSB} port listen connection OUTPUT: none
9.3.10 TCPAppActiveOpen()
example, initiate connect remote TCP. INPUT: {tcb1LocalPortMSB, tcb1LocalPortLSB} port listen connection {tcb2LocalPortMSB, tcb2LocalPortLSB} port listen connection {tcb1RemotePortMSB, tcb1RemotePortLSB} remote port establish connection with connection {tcb2RemotePortMSB, tcb2RemotePortLSB} remote port establish connection with connection {sock1RemoteIP3-0} remote address connection {sock2RemoteIP3-0} remote address connection OUTPUT: none
9.3.11 TCPAppClose()
Force current connection close. INPUT: none OUTPUT: none
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Server Send Email Client Implementation with Ethernet Physical Layer
AN37
Variables
9.4.1 sock1RemoteIP[3:0], sock2RemoteIP[3:0]
address remote end-point which connection been, established.
9.4.2 myIP[3:0]
address local end-point. This usually address assigned
9.4.3 tcb1LocalPortMSB, tcb1LocalPortLSB, tcb2LocalPortMSB, tcb2LocalPortLSB
Local port number each connection. connection `end-point' specified unique pair comprising node's address, well socket, `port' number.
9.4.4 tcb1RemotePortMSB, tcb1RemotePortLSB, tcb2RemotePortMSB, tcb2RemotePortLSB
Remote port number each connection. connection `end-point' specified unique pair comprising node's address, well socket, `port' number.
SMTP functions
9.5.1 _senderDomainName
Contains send email client's domain name. Example: Ethernet SX-Stack board's email address eSX@acme.com, sender's domain name acme.com.
9.5.2 _mailFrom
Contains sender's name. Example: EthernetSX-Stack board's email address eSX@acme.com, sender's name eSX.
9.5.3 _mailTo
Contains recipient's email address. Example: Ethernet SX-Stack board sends email joe@demo.sx, recipient's email address joe@demo.sx
9.5.4 _mailData
Contains data email message.
Variables
9.6.1 SMTP_SERVER_IP[3:0]
address SMTP server contacted when sending email. Example: SMTP server's address 168.75.232.39, SMTP_SERVER_IP3=168, SMTP_SERVER_IP2=75, SMTP_SERVER_IP1=232, SMTP_SERVER_IP0=39
9.6.2 smtpState
Contains current state SMTP state machine. Must equal SMTP_CONNECT start state machine send ail.
9.6.3 flags3.SMTP_OK
flag that indicates SMTP state machine finished successfully (email accepted remote SMTP server). Equals successful error encountered.
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Server Send Email Client Implementation with Ethernet Physical Layer
AN37
Appendix Ethernet SX-Stack Demo Board Schematic
Following description elements schematic: frequency crystal/resonator, changed user, since TCP/IP protocol stack non-real time operates almost exclusively mainline context. course, certain restrictions apply. example, receive buffer should allowed overflow, packets will lost. loaded lieu cost-reduction (will reduce speed 20MIPS). supplied code will only work with SX52 Revision silicon (the production-release version). Whilst supplied reference design demonstration code works with prescribed pinouts, general, pinouts changed with little modification code. Some components reference design only used demonstration purposes, please Billof-Materials section list core components. Connectors future expansion. 32KB Serial EEPROM, used storing data only. Thus, users need HTTP need have this component their design. (and associated components) used reprogramming Serial EEPROM (U3). R10, implement temperature sensor, which will provide real-time data displayed dynamic web-page demonstration purposes. demonstration purposes only. reference design hardcodes 48-bit Ethernet physical address which FLASH-reprogrammable. user also store physical address separate configuration device attaching 9346 Serial 1k-bit EEPROM BD[5:7] Refer Sect. RTL8019AS datasheet more information. In-System-Programming (ISP) header. (re)programmed using just OSC1and OSC2 pins. more information visit http://www.realtek.com.tw/cn information ordering pricing visit more information visit information ordering pricing visit
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Server Send Email Client Implementation with Ethernet Physical Layer
AN37
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Server Send Email Client Implementation with Ethernet Physical Layer
AN37
Appendix Bill Material
reference designators highlighted bold components either used only demonstration purposes, whose optional.
C1,2 C10-12,15,16 C3,25,26,31,32 C4-9,14,1722,24,27,29,30 D3,4 FB1,2 JP1,6 R2,4,7,10,14 R3,5,8,9,12,13 R6,11,15 S1,2
47uF 0.1uF 0.01uF 0.1uF 4.7K 32Kx8 50MHz 20MHz
Description Electrolytic capacitor Ceramic capacitor SMT0805 Ceramic capacitor SMT0805 Ceramic capacitor SMT1206 Ceramic capacitor SMT0603 Orange Rectifier diode MELF Green Amber Ferrite bead SMT0805 2.0mm Power jack Modular connector 10pin dual male header 4pin single male header 2pin single male header 18pin dual male header thermistor SMT0805 Carbon film resistor SMT0603 Carbon film resistor SMT0603 Carbon film resistor SMT0603 Carbon film resistor SMT0603 Tact switch Filter transformer RS232 transceiver SOIC16 Comms controller PQFP52 Serial EEPROM SOIC8 Voltage regulator D^2PAK Ethernet controller QFP100-14 Ceramic resonator Crystal CSM-7
Part Panasonic: ECE-V1EA470UP Panasonic: ECJ-2VF1C105Z Panasonic: ECJ-2YB1H104K Panasonic: ECU-V1H103KBM Panasonic: ECJ-1VB1C104K Panasonic: LNJ808R8ERA Diodes Inc: DL4001 Panasonic: LNJ208R8ARA Panasonic: LNJ308G8TRA Panasonic: LNJ408K8ZRA Panasonic: EXC-ML20A390U Stack: PJ-002A AMP: 520426-4 Digikey: S2012-05-ND Digikey: S1012-04-ND Digikey: S1012-02-ND Digikey: S2012-09-ND Thermometrics: NC0805R502T10 Panasonic: ERJ-3GSYJ201V Panasonic: ERJ-3GSYJ103V
ERJ-3GSYJ471V Panasonic: ERJ-3GSYJ472V
Panasonic: Omron: B3S-1002 Bothhand: FB2022 Intersil: ICL232CBE Ubicom: SX52BD/PQ Microchip: 24LC256-I/SM L7805CD2T Realtek: RTL8019AS Murata: CSTCV50.00MXJ0H3 ECS: ECS-200-20-5P
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Server Send Email Client Implementation with Ethernet Physical Layer
AN37
Appendix References
AN23: PPP/UDP Virtual Peripheral Implementation [Ubicom] AN27: Virtual Peripheral Implementation [Ubicom] AN25: HTTP Virtual Peripheral Implementation [Ubicom] RTL8019 Datasheet [Realtek] RTL8019AS Datasheet [Realtek] DP83905 Datasheet [National Semiconductor] Internetworking with TCP/IP Volume Edition [Douglas Comer] RFC1533: DHCP Options RFC1541: DHCP 10.RFC791: 11.RFC792: ICMP 12.RFC793: 13.RFC951: BOOTP 14.RFC768:
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Server Send Email Client Implementation with Ethernet Physical Layer
AN37
AN37-05
Sales Tech Support Contact Information
latest contact support information devices, please visit Ubicom website www.ubicom.com. site contains technical literature, local sales contacts, tech support many other features.
1330 Charleston Road Mountain View, 94043 Contact: sales@ubicom.com http://www.ubicom.com Tel.: (650) 210-1500 Fax: (650) 210-8715
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