AN2120: Connecting an M68HC08 Family Microcontroller to an ...

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Application Note The most common LCP negotiations happening during initial connection are maximum-receive-unit, protocol-field-compression, magic-number, authentication-protocol and async-control-character-map, all described in RFC1661 and RFC1662. This application note tries to force negotiations to go our way. It first tries to use the default settings provided by the ISP and goes from there. However, different implementations should modify the state machine inside HandleLCPOptions () routine to handle LCP options differently. Password Authentication Protocol (PAP) The password authentication protocol is defined in RFC 1334. PAP is intended primarily for use by hosts and routers that connect to a PPP network server commonly via dial-up lines, but it might be applied to dedicated point-to-point links as well. The server can use the identification of the connecting host or router in the selection of options for network layer negotiations. The authenticate-request packet format is shown in Figure 17. 1 BYTE 1 BYTE 2 BYTES CODE IDENTIFIER USER ID LENGTH LENGTH 1 BYTE LENGTH BYTES USER ID ... 1 BYTE LENGTH BYTES PASSWORD LENGTH PASSWORD PPP HEADER 7F FF 03 C0 23 01 05 00 0A 00 PPP CHECKSUM 04 72 65 6E 65 D9 FA 7F Figure 17. PAP Packet Layout and Sample — User ID = "", Password = "rene" AN2120 22 MOTOROLA
Internet Protocol Control Protocol PPP Negotiations AN2120 Application Note Internet Protocol Control Protocol After the PPP host has been authenticated, the next phase is the network-layer protocol. The Internet protocol control protocol (IPCP) is used to configure the Internet protocol environment to be used in a PPP link. Options such as IP address, IP compression, primary DNS server, etc., are negotiated using IPCP. The format of an IPCP frame is similar to that of LCP: a 1 byte negotiation code followed by ID, length, and options. Once the IP protocol has been configured, datagrams from each network can be sent in both direction over the link. Further details of IPCP are covered in RFC 1332. All LCP negotiations are performed in a state machine implemented inside the PPP.C module. When the first LCP packet arrives from the ISP, the state machine responds with a NAK packet with the same options the ISP sent us before. This will force the ISP to reply with a request for the authentication protocol to be used. The negotiation flow is shown in Figure 18. MOTOROLA 23
Page 1 and 2: © Motorola, Inc., 2001 Semiconduct
Page 3 and 4: Internet Primer AN2120 M68HC08 FAMI
Page 5 and 6: AN2120 A1 A2 A3 NETWORK A B1 B2 B3
Page 7 and 8: AN2120 OSI REFERENCE MODEL INTERNET
Page 9 and 10: AN2120 Application Note Internet Pr
Page 11 and 12: UDP Protocol AN2120 Application Not
Page 13 and 14: AN2120 Application Note Internet Co
Page 15 and 16: Dialing an Internet Service Provide
Page 17 and 18: Start Flag 0x7F PPP Framing AN2120
Page 19 and 20: AN2120 Application Note PPP Framing
Page 21: AN2120 Field Type A description of
Page 25 and 26: AN2120 (1) First LCP packet sent by
Page 27 and 28: AN2120 Application Note Serial Line
Page 29 and 30: Software Operation AN2120 Applicati
Page 31 and 32: AN2120 Table 4. MC68HC908GP32 Inter
Page 33 and 34: Overview of the Modem Interface AN2
Page 35 and 36: AN2120 Application Note Operation o
Page 37 and 38: AN2120 FIFO INITIALIZED FIFO AT RUN
Page 39 and 40: PPP Module AN2120 InBuffer [0] InBu
Page 41 and 42: Listing 4. Body of PPPEntry Functio
Page 43 and 44: AN2120 Application Note Internet Pr
Page 45 and 46: AN2120 Application Note Summary Int
Page 47 and 48: Code Implementation AN2120 Applicat
Page 49 and 50: CommEventProc (ProcPPPReceive); //
Page 51 and 52: AN2120 Application Note Code Implem
Page 53 and 54: ***********************************
Page 55 and 56: Parameters : Date : July 2000 Desc
Page 57 and 58: } AN2120 } else { } Application Not
Page 59 and 60: } AN2120 } case ICMP: IcmpHandler (
Page 61 and 62: ***********************************
Page 63 and 64: } AN2120 } else { } PPPStatus &= ~I
Page 65 and 66: AN2120 switch (InBuffer [4] ) { App
Page 67 and 68: } AN2120 //////////////////////////
Page 69 and 70: } AN2120 } break; case REJ: break;
Page 71 and 72: This will force the server to reply
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#include "CommDrv.h" #include "Mode
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***********************************
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} AN2120 } return False; /*********
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***********************************
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} AN2120 } Data+=2; Sum = (Sum >> 1
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} AN2120 Checksum = IPCheckSum (&ud
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*/ #include "IP.h" #include "ICMP.h
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PLL.C Code of InitPLL Function /*//
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BUSFREQ: EQU 2 _1msDelay: PSHA ;2 c
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Current Revision : 0.0 Notes : Defi
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#define ESC_ESC 0xDD //335 octal ex
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void IPBindAdapter (INTERFACE Inter
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Delay.h Header Definitions for Dela
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WORD CommPort (void) { return Port;
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CommDrv.H Serial Communications Int
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AN2120 Application Note Code Implem
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