GSM/GPRS module and PPP protocol

Vitor M

# 11 Dec 2010 . Edited: 11 Dec 2010

-----------GPRS/GSM for mbed at low cost for WEB connection/SMS/callings---------

I found a low cost GSM/GPRS module such this used in this project . http://finch.am/projects/arduinogsm/ it can be used for both SMS, calls and internet acess via GPRS for only $25

This module is a perfect add on to mbed for GSM communication

The only problem with GPRS connection to acess WEB is that this module need to do the PPP negotiation for getting WEB acess

Using AT commands over serial port after doing the ATDT*99***1# it get the CONNECTED, bellow is a sniff of serial port for the process to connect to site www.google.com and receive it. (using the module software)

Any one as the knowledge how the PPP negotiation is implemented?

According to the protocol http://www.tcpipguide.com/free/t_PPPGeneralFrameFormat.htm . The frames start and end with 7E (Hexadecimal) flag as we can see bellow.

Any ideias are welcome for a kind of emulation for get GPRS connections on mbed via serial port

Request: 11-12-2010 16:07:07.71864 (+0.0156 seconds)

 41 54 44 54 2A 39 39 2A 2A 2A 31 23 0D            ATDT*99***1#.   

Answer: 11-12-2010 16:07:07.71864 (+0.0000 seconds)

 0D 0A 43 4F 4E 4E 45 43 54 0D 0A                  ..CONNECT..     

Request: 11-12-2010 16:07:07.78064 (+0.0625 seconds)

 7E FF 7D 23 C0 21 7D 21 7D 20 7D 20 32 7D 22 7D   ~ÿ}#À!}!} } 2}"}
 26 7D 20 7D 20 7D 20 7D 20 7D 25 7D 26 36 77 78   &} } } } }%}&6wx
 D8 7D 27 7D 22 7D 28 7D 22 7D 2D 7D 23 7D 26 7D   Ø}'}"}(}"}-}#}&}
 31 7D 24 7D 26 4E 7D 33 7D 37 7D 21 EA 71 B3 28   1}$}&N}3}7}!êq³(
 9C 7D 21 48 CB 89 4D A8 6C B2 BA 25 A4 7D 20 7D   }!HËM¨l²º%¤} }
 20 7D 20 7D 20 7D 32 8E 7E                         } } }2~       

Answer: 11-12-2010 16:07:07.78064 (+0.0000 seconds)

 7E FF 7D 23 C0 21 7D 24 7D 20 7D 20 28 7D 25 7D   ~ÿ}#À!}$} } (}%}
 26 36 77 78 D8 7D 2D 7D 23 7D 26 7D 31 7D 24 7D   &6wxØ}-}#}&}1}$}
 26 4E 7D 33 7D 37 7D 21 EA 71 B3 28 9C 7D 21 48   &N}3}7}!êq³(}!H
 CB 89 4D A8 6C B2 BA 25 A4 7D 20 7D 20 7D 20 7D   ËM¨l²º%¤} } } }
 20 3D 91 7E                                        =~            

Request: 11-12-2010 16:07:07.79664 (+0.0000 seconds)

 7E FF 7D 23 C0 21 7D 21 7D 21 7D 20 7D 2E 7D 22   ~ÿ}#À!}!}!} }.}"
 7D 26 7D 20 7D 20 7D 20 7D 20 7D 27 7D 22 7D 28   }&} } } } }'}"}(
 7D 22 70 34 7E                                    }"p4~           

Answer: 11-12-2010 16:07:07.79664 (+0.0000 seconds)

 7E FF 7D 23 C0 21 7D 22 7D 21 7D 20 7D 2E 7D 22   ~ÿ}#À!}"}!} }.}"
 7D 26 7D 20 7D 20 7D 20 7D 20 7D 27 7D 22 7D 28   }&} } } } }'}"}(
 7D 22 4E B7 7E 7E FF 7D 23 C0 21 7D 21 7D 25 7D   }"N·~~ÿ}#À!}!}%}
 20 7D 33 7D 22 7D 26 7D 20 7D 20 7D 20 7D 20 7D    }3}"}&} } } } }
 23 7D 25 C2 23 7D 25 7D 27 7D 22 7D 28 7D 22 F8   #}%Â#}%}'}"}(}"ø
 EB 7E                                             ë~              

Request: 11-12-2010 16:07:10.68764 (+0.0000 seconds)

 7E FF 7D 23 C0 21 7D 22 7D 25 7D 20 7D 33 7D 22   ~ÿ}#À!}"}%} }3}"
 7D 26 7D 20 7D 20 7D 20 7D 20 7D 23 7D 25 C2 23   }&} } } } }#}%Â#
 7D 25 7D 27 7D 22 7D 28 7D 22 32 56 7E 7E C0 21   }%}'}"}(}"2V~~À!
 0C 02 00 12 36 77 78 D8 4D 53 52 41 53 56 35 2E   ....6wxØMSRASV5.
 31 30 3B 87 7E 7E C0 21 0C 03 00 1F 36 77 78 D8   10;~~À!....6wxØ
 4D 53 52 41 53 2D 30 2D 56 49 4B 54 4F 52 2D 30   MSRAS-0-VIKTOR-0
 35 41 37 38 39 30 34 68 6F 7E                     5A78904ho~      

Answer: 11-12-2010 16:07:10.68764 (+0.0000 seconds)

 7E C2 23 01 03 00 16 11 FF FB BD 93 A0 03 4D 63   ~Â#.....ÿû½ .Mc
 24 7D 5F DB 04 C2 80 30 4E 41 6C 5B 7E            $}_Û.Â0NAl[~   

Request: 11-12-2010 16:07:10.68764 (+0.0000 seconds)

 7E C2 23 02 03 00 15 10 52 82 33 8C FA D4 DA 95   ~Â#.....R3úÔÚ
 1F B7 EC C0 7D 5E 98 91 73 1C A5 7E               .·ìÀ}^s.¥~    

Answer: 11-12-2010 16:07:10.68764 (+0.0000 seconds)

 7E FF 7D 23 C0 21 7D 27 7D 25 7D 20 7D 36 7D 2C   ~ÿ}#À!}'}%} }6},
 7D 22 7D 20 7D 32 36 77 78 D8 4D 53 52 41 53 56   }"} }26wxØMSRASV
 35 2E 31 30 60 A1 7E 7E FF 7D 23 C0 21 7D 27 7D   5.10`¡~~ÿ}#À!}'}
 26 7D 20 23 7D 2C 7D 23 7D 20 7D 3F 36 77 78 D8   &} #},}#} }?6wxØ
 4D 53 52 41 53 2D 30 2D 56 49 4B 54 4F 52 2D 30   MSRAS-0-VIKTOR-0
 35 41 37 38 39 30 34 6E DB 7E 7E C2 23 03 03 00   5A78904nÛ~~Â#...
 04 7A 09 7E                                       .z.~            

Request: 11-12-2010 16:07:10.70264 (+0.0000 seconds)

 7E 80 FD 01 04 00 0A 12 06 00 00 00 01 C3 2F 7E   ~ý..........Ã/~
 7E 80 21 01 05 00 28 02 06 00 2D 0F 01 03 06 00   ~!...(...-.....
 00 00 00 81 06 00 00 00 00 82 06 00 00 00 00 83   .............
 06 00 00 00 00 84 06 00 00 00 00 3E 6F 7E         ..........>o~  

Answer: 11-12-2010 16:07:10.71864 (+0.0156 seconds)

 7E FF 7D 23 C0 21 7D 28 7D 23 7D 20 7D 30 80 FD   ~ÿ}#À!}(}#} }0ý
 7D 21 7D 24 7D 20 7D 2A 7D 32 7D 26 7D 20 7D 20   }!}$} }*}2}&} } 
 7D 20 7D 21 7D 3A 4E 7E                           } }!}:N~        

Request: 11-12-2010 16:07:11.79664 (+1.0781 seconds)

 7E 80 21 01 06 00 28 02 06 00 2D 0F 01 03 06 00   ~!...(...-.....
 00 00 00 81 06 00 00 00 00 82 06 00 00 00 00 83   .............
 06 00 00 00 00 84 06 00 00 00 00 0C B0 7E         ...........°~  

Answer: 11-12-2010 16:07:12.23364 (+0.4375 seconds)

 7E 80 21 01 03 00 0A 03 06 5D 6C 47 3D E8 42 7E   ~!......]lG=èB~
 7E 80 21 04 06                                    ~!..           

Request: 11-12-2010 16:07:12.24964 (+0.0000 seconds)

 7E 80 21 02 03 00 0A 03 06 5D 6C 47 3D 81 36 7E   ~!......]lG=6~

Answer: 11-12-2010 16:07:12.24964 (+0.0000 seconds)

 00 16 02 06 00 2D 0F 01 82 06 00 00 00 00 84 06   .....-........
 00 00 00 00 A8 56 7E                              ....¨V~         

Request: 11-12-2010 16:07:12.24964 (+0.0000 seconds)

 7E 80 21 01 07 00 16 03 06 00 00 00 00 81 06 00   ~!............
 00 00 00 83 06 00 00 00 00 66 F8 7E               ........fø~    

Answer: 11-12-2010 16:07:12.24964 (+0.0000 seconds)

 7E 80 21 03 07 00 16 03 06 5D 6C 47 3D 81 06 D4   ~!......]lG=.Ô
 12 A0 85 83 06 D4 12 A0 86 41 24 7E               . .Ô. A$~    

Request: 11-12-2010 16:07:12.26564 (+0.0000 seconds)

 7E 80 21 01 08 00 16 03 06 5D 6C 47 3D 81 06 D4   ~!......]lG=.Ô
 12 A0 85 83 06 D4 12 A0 86 9F 49 7E               . .Ô. I~    

Answer: 11-12-2010 16:07:12.26564 (+0.0000 seconds)

 7E 80 21 02 08 00 16 03 06 5D 6C 47 3D 81 06 D4   ~!......]lG=.Ô
 12 A0 85 83 06 D4 12 A0 86 69 BA 7E               . .Ô. iº~    

Request: 11-12-2010 16:07:12.32764 (+0.0625 seconds)

 7E 21 45 00 01 48 F3 CC 00 00 80 11 A1 2F 5D 6C   ~!E..HóÌ...¡/]l
 47 3D FF FF FF FF 00 44 00 43 01 34 D8 1F 01 08   G=ÿÿÿÿ.D.C.4Ø...
 06 00 08 AA 7F 27 06 00 00 00 5D 6C 47 3D 00 00   ...ª'....]lG=..
 00 00 00 00 00 00 00 00 00 00 00 53 45 00 00 00   ...........SE...
 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
 00 00 00 00 00 00 00 00 00 00 63 82 53 63 35 01   ..........cSc5.
 08 3D 07 08 00 53 45 00 00 00 0C 0F 76 69 6B 74   .=...SE.....vikt
 6F 72 2D 30 35 61 37 38 39 30 34 3C 08 4D 53 46   or-05a78904<.MSF
 54 20 35 2E 30 37 06 06 2C 2B 01 F9 0F 2B 03 DC   T 5.07..,+.ù.+.Ü
 01 00 FF 00 00 00 00 00 00 00 AF 0D 7E 7E 21 45   ..ÿ.......¯.~~!E
 00 00 A1 F3 CD 00 00 01 11 30 DB 5D 6C 47 3D EF   ..¡óÍ....0Û]lG=ï
 FF FF FA 07 09 07 6C 00 8D B5 D1 4D 2D 53 45 41   ÿÿú...l.µÑM-SEA
 52 43 48 20 2A 20 48 54 54 50 2F 31 2E 31 0D 0A   RCH * HTTP/1.1..
 48 6F 73 74 3A 32 33 39 2E 32 35 35 2E 32 35 35   Host:239.255.255
 2E 32 35 30 3A 31 39 30 30 0D 0A 53 54 3A 75 72   .250:1900..ST:ur
 6E 3A 73 63 68 65 6D 61 73 2D 75 70 6E 70 2D 6F   n:schemas-upnp-o
 72 67 3A 64 65 76 69 63 65 3A 49 6E 74 65 72 6E   rg:device:Intern
 65 74 47 61 74 65 77 61 79 44 65 76 69 63 65 3A   etGatewayDevice:
 31 0D 0A 4D 61 6E 3A 22 73 73 64 70 3A 64 69 73   1..Man:"ssdp:dis
 63 6F 76 65 72 22 0D 0A 4D 58 3A 33 0D 0A 0D 0A   cover"..MX:3....
 4E AF 7E 7E 21 45 00 01 48 F3 D0 00 00 80 11 A1   N¯~~!E..HóÐ...¡
 2B 5D 6C 47 3D FF FF FF FF 00 44 00 43 01 34 D5   +]lG=ÿÿÿÿ.D.C.4Õ
 1F 01 08 06 00 08 AA 7F 27 09 00 00 00 5D 6C 47   ......ª'....]lG
 3D 00 00 00 00 00 00 00 00 00 00 00 00 00 53 45   =.............SE
 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
 00 00 00 00 00 00 00 00 00 00 00 00 00 63 82 53   .............cS
 63 35 01 08 3D 07 08 00 53 45 00 00 00 0C 0F 76   c5..=...SE.....v
 69 6B 74 6F 72 2D 30 35 61 37 38 39 30 34 3C 08   iktor-05a78904<.
 4D 53 46 54 20 35 2E 30 37 06 06 2C 2B 01 F9 0F   MSFT 5.07..,+.ù.
 2B 03 DC 01 00 FF 00 00 00 00 00 00 00 9D 1F 7E   +.Ü..ÿ........~
 7E 21 45 00 00 3C F3 D6 00 00 80 11 2D 99 5D 6C   ~!E..<óÖ...-]l
 47 3D D4 12 A0 85 FA C0 00 35 00 28 A4 93 B8 2B   G=Ô. úÀ.5.(¤¸+
 01 00 00 01 00 00 00 00 00 00 03 77 77 77 06 67   ...........www.g
 6F 6F 67 6C 65 03 63 6F 6D 00 00 01 00 01 18 6A   oogle.com......j
 7E 7E 21 45 00 00 3C F3 D7 00 00 80 11 2D 98 5D   ~~!E..<ó×...-]
 6C 47 3D D4 12 A0 85 EE 57 00 35 00 28 8C F6 DC   lG=Ô. îW.5.(öÜ
 31 01 00 00 01 00 00 00 00 00 00 03 77 77 77 06   1...........www.
 67 6F 6F 67 6C 65 03 63 6F 6D 00 00 01 00 01 C1   google.com.....Á
 3C 7E                                             <~   



Above we can see in the frame it make a request to www.google.com- - - - - - - - - - - - - - 

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - – – - - - - - - - - - - - -           



Answer: 11-12-2010 16:07:42.43764 (+0.4844 seconds)

 7E 21 45 00 01 28 00 00 40 00 3C 11 24 84 D4 12   ~!E..(..@.<.$Ô.
 A0 85 5D 6C 47 3D 00 35 FA C0 01 14 22 7B B8 2B    ]lG=.5úÀ.."{¸+
 81 80 00 01 00 06 00 04 00 04 03 77 77 77 06 67   .........www.g
 6F 6F 67 6C 65 03 63 6F 6D 00 00 01 00 01 C0 0C   oogle.com.....À.
 00 05 00 01 00 08 A8 59 00 08 03 77 77 77 01 6C   ......¨Y...www.l
 C0 10 C0 2C 00 01 00 01 00 00 00 55 00 04 4A 7D   À.À,.......U..J}
 5D E6 52 C0 2C 00 01 00 01 00 00 00 55 00 04 4A   ]æRÀ,.......U..J
 7D 5D E6 53 C0 2C 00 01 00 01 00 00 00 55 00 04   }]æSÀ,.......U..
 4A 7D 5D E6 54 C0 2C 00 01 00 01 00 00 00 55 00   J}]æTÀ,.......U.
 04 4A 7D 5D E6 50 C0 2C 00 01 00 01 00 00 00 55   .J}]æPÀ,.......U
 00 04 4A 7D 5D E6 51 C0 10 00 02 00 01 00 02 10   ..J}]æQÀ........
 D8 00 06 03 6E 73 33 C0 10 C0 10 00 02 00 01 00   Ø...ns3À.À......
 02 10 D8 00 06 03 6E 73 34 C0 10 C0 10 00 02 00   ..Ø...ns4À.À....
 01 00 02 10 D8 00 06 03 6E 73 31 C0 10 C0 10 00   ....Ø...ns1À.À..
 02 00 01 00 02 10 D8 00 06 03 6E 73 32 C0 10 C0   ......Ø...ns2À.À
 B4 00 01 00 01 00 03 64 B0 00 04 D8 EF 20 0A C0   ´......d°..Øï .À
 C6 00 01 00 01 00 03 64 B0 00 04 D8 EF 22 0A C0   Æ......d°..Øï".À
 90 00 01 00 01 00 03 64 B0 00 04 D8 EF 24 0A C0   ......d°..Øï$.À
 A2 00 01 00 01 00 03 64 B0 00 04 D8 EF 26 0A 86   ¢......d°..Øï&.
 CC 7E 7E 21 45 00 01 28 00 00 40 00 3C 11 24 84   Ì~~!E..(..@.<.$
 D4 12 A0 85 5D 6C 47 3D 00 35 EE 57 01 14 0A DE   Ô. ]lG=.5îW...Þ
 DC 31 81 80 00 01 00 06 00 04 00 04 03 77 77 77   Ü1.........www
 06 67 6F 6F 67 6C 65 03 63 6F 6D 00 00 01 00 01   .google.com.....
 C0 0C 00 05 00 01 00 08 A8 59 00 08 03 77 77 77   À.......¨Y...www
 01 6C C0 10 C0 2C 00 01 00 01 00 00 00 55 00 04   .lÀ.À,.......U..
 4A 7D 5D E6 53 C0 2C 00 01 00 01 00 00 00 55 00   J}]æSÀ,.......U.
 04 4A 7D 5D E6 54 C0 2C 00 01 00 01 00 00 00 55   .J}]æTÀ,.......U
 00 04 4A 7D 5D E6 50 C0 2C 00 01 00 01 00 00 00   ..J}]æPÀ,.......
 55 00 04 4A 7D 5D E6 51 C0 2C 00 01 00 01 00 00   U..J}]æQÀ,......
 00 55 00 04 4A 7D 5D E6 52 C0 10 00 02 00 01 00   .U..J}]æRÀ......
 02 10 D8 00 06 03 6E 73 31 C0 10 C0 10 00 02 00   ..Ø...ns1À.À....
 01 00 02 10 D8 00 06 03 6E 73 32 C0 10 C0 10 00   ....Ø...ns2À.À..
 02 00 01 00 02 10 D8 00 06 03 6E 73 33 C0 10 C0   ......Ø...ns3À.À
 10 00 02 00 01 00 02 10 D8 00 06 03 6E 73 34 C0   ........Ø...ns4À
 10 C0 90 00 01 00 01 00 03 64 B0 00 04 D8 EF 20   .À......d°..Øï 
 0A C0 A2 00 01 00 01 00 03 64 B0 00 04 D8 EF 22   .À¢......d°..Øï"
 0A C0 B4 00 01 00 01 00 03 64 B0 00 04 D8 EF 24   .À´......d°..Øï$
 0A C0 C6 00 01 00 01 00 03 64 B0 00 04 D8 EF 26   .ÀÆ......d°..Øï&
 0A 94 9B 7E                                       .~            

Request: 11-12-2010 16:07:42.54664 (+0.0000 seconds)

 7E 21 45 00 00 30 F3 D8 40 00 80 06 31 75 5D 6C   ~!E..0óØ@..1u]l
 47 3D 4A 7D 5D E6 53 07 0E 00 50 72 F2 8F E5 00   G=J}]æS...Pròå.
 00 00 00 70 02 40 00 63 6F 00 00 02 04 05 B4 01   ...p.@.co.....´.
 01 04 02 16 E2 7E                                 ....â~          

Answer: 11-12-2010 16:07:43.14064 (+0.5938 seconds)

 7E 21 45 00 00 30 C7 10 00 00 37 06 E7 3D 4A 7D   ~!E..0Ç...7.ç=J}
 5D E6 53 5D 6C 47 3D 00 50 07 0E FA AD A3 84 72   ]æS]lG=.P..ú£r
 F2 8F E6 70 12 16 58 EF 37 00 00 02 04 05 50 01   òæp..Xï7.....P.
 01 04 02 3F 14 7E                                 ...?.~          

Request: 11-12-2010 16:07:43.14064 (+0.0000 seconds)

 7E 21 45 00 00 28 F3 DA 40 00 80 06 31 7B 5D 6C   ~!E..(óÚ@..1{]l
 47 3D 4A 7D 5D E6 53 07 0E 00 50 72 F2 8F E6 FA   G=J}]æS...Pròæú
 AD A3 85 50 10 45 10 EC DF 00 00 0A 49 7E 7E 21   £P.E.ìß...I~~!
 45 00 02 01 F3 DC 40 00 80 06 2F A0 5D 6C 47 3D   E...óÜ@../ ]lG=
 4A 7D 5D E6 53 07 0E 00 50 72 F2 8F E6 FA AD A3   J}]æS...Pròæú£
 85 50 18 45 10 05 51 00 00 47 45 54 20 2F 20 48   P.E..Q..GET / H
 54 54 50 2F 31 2E 31 0D 0A 41 63 63 65 70 74 3A   TTP/1.1..Accept:
 20 2A 2F 2A 0D 0A 41 63 63 65 70 74 2D 4C 61 6E    */*..Accept-Lan
 67 75 61 67 65 3A 20 70 74 0D 0A 55 73 65 72 2D   guage: pt..User-
 41 67 65 6E 74 3A 20 4D 6F 7A 69 6C 6C 61 2F 34   Agent: Mozilla/4
 2E 30 20 28 63 6F 6D 70 61 74 69 62 6C 65 3B 20   .0 (compatible; 
 4D 53 49 45 20 38 2E 30 3B 20 57 69 6E 64 6F 77   MSIE 8.0; Window
 73 20 4E 54 20 35 2E 31 3B 20 54 72 69 64 65 6E   s NT 5.1; Triden
 74 2F 34 2E 30 3B 20 41 73 6B 54 62 46 58 54 56   t/4.0; AskTbFXTV
 35 2F 35 2E 39 2E 31 2E 31 34 30 31 39 29 0D 0A   5/5.9.1.14019)..
 41 63 63 65 70 74 2D 45 6E 63 6F 64 69 6E 67 3A   Accept-Encoding:
 20 67 7A 69 70 2C 20 64 65 66 6C 61 74 65 0D 0A    gzip, deflate..
 48 6F 73 74 3A 20 77 77 77 2E 67 6F 6F 67 6C 65   Host: www.google
 2E 63 6F 6D 0D 0A 43 6F 6E 6E 65 63 74 69 6F 6E   .com..Connection
 3A 20 4B 65 65 70 2D 41 6C 69 76 65 0D 0A 43 6F   : Keep-Alive..Co
 6F 6B 69 65 3A 20 50 52 45 46 3D 49 44 3D 64 38   okie: PREF=ID=d8
 34 62 66 62 36 35 66 35 30 38 65 61 31 36 3A 55   4bfb65f508ea16:U
 3D 37 39 61 35 36 62 66 35 38 61 64 39 36 66 64   =79a56bf58ad96fd
 38 3A 46 46 3D 30 3A 54 4D 3D 31 32 39 31 39 30   8:FF=0:TM=129190
 35 37 34 32 3A 4C 4D 3D 31 32 39 31 39 33 35 33   5742:LM=12919353
 34 38 3A 53 3D 5F 56 41 6D 62 4C 59 52 41 77 32   48:S=_VAmbLYRAw2
 65 54 78 33 77 3B 20 4E 49 44 3D 34 31 3D 52 6D   eTx3w; NID=41=Rm
 53 67 6E 55 35 31 53 6A 52 37 36 6F 2D 45 6C 6F   SgnU51SjR76o-Elo
 35 30 59 72 65 35 6C 6F 38 6C 41 55 72 45 50 48   50Yre5lo8lAUrEPH
 5F 72 6F 64 65 59 68 4E 5F 62 74 6B 73 62 64 74   _rodeYhN_btksbdt
 52 71 45 73 72 75 36 6A 61 41 66 30 31 70 4C 4D   RqEsru6jaAf01pLM
 45 53 5F 49 76 49 73 49 78 56 66 32 57 65 4E 4C   ES_IvIsIxVf2WeNL
 63 72 32 74 52 48 78 6C 75 4E 4A 58 39 77 4A 33   cr2tRHxluNJX9wJ3
 32 42 71 47 71 4C 62 46 48 79 54 73 44 6B 6C 59   2BqGqLbFHyTsDklY
 63 6A 31 41 42 46 6C 72 73 6E 79 6A 64 4D 0D 0A   cj1ABFlrsnyjdM..
 0D 0A 14 C3 7E                                    ...Ã~

*** Above we can see that in this frame is done the GET request to google- - -  - - - - - - - - - - - - - - - - 
*GET / HTTP/1.1 …...........    (Line 6 and 7) (http protocol)- - - - - - - - - - - - - - - - - - - - - - - - -


Answer: 11-12-2010 16:07:43.62464 (+0.4531 seconds)

 7E 21 45 00 00 30 C7 11 00 00 37 06 E7 3C 4A 7D   ~!E..0Ç...7.ç<J}
 5D E6 53 5D 6C 47 3D 00 50 07 0E FA AD A3 84 72   ]æS]lG=.P..ú£r
 F2 8F E6 70 12 16 58 EF 37 00 00 02 04 05 50 01   òæp..Xï7.....P.
 01 04 02 A4 C1 7E                                 ...¤Á~          

Request: 11-12-2010 16:07:43.62464 (+0.0000 seconds)

 7E 21 45 00 00 28 F3 DD 40 00 80 06 31 78 5D 6C   ~!E..(óÝ@..1x]l
 47 3D 4A 7D 5D E6 53 07 0E 00 50 72 F2 91 BF FA   G=J}]æS...Prò¿ú
 AD A3 85 50 10 45 10 EB 06 00 00 4A 0B 7E         £P.E.ë...J.~  

Answer: 11-12-2010 16:07:44.93764 (+0.3125 seconds)

 7E 21 45 00 00 28 C7 12 00 00 37 06 E7 43 4A 7D   ~!E..(Ç...7.çCJ}
 5D E6 53 5D 6C 47 3D 00 50 07 0E FA AD A3 85 72   ]æS]lG=.P..ú£r
 F2 91 BF 50 10 19 20 16 F7 00 00 52 B0 7E 7E 21   ò¿P.. .÷..R°~~!
 45 00 01 E1 C7 13 00 00 37 06 E5 89 4A 7D 5D E6   E..áÇ...7.åJ}]æ
 53 5D 6C 47 3D 00 50 07 0E FA AD A3 85 72 F2 91   S]lG=.P..ú£rò
 BF 50 18 19 20 47 B0 00 00 48 54 54 50 2F 31 2E   ¿P.. G°..HTTP/1.
 31 20 33 30 32 20 46 6F 75 6E 64 0D 0A 4C 6F 63   1 302 Found..Loc
 61 74 69 6F 6E 3A 20 68 74 74 70 3A 2F 2F 77 77   ation: http://ww
 77 2E 67 6F 6F 67 6C 65 2E 70 74 2F 0D 0A 43 61   w.google.pt/..Ca
 63 68 65 2D 43 6F 6E 74 72 6F 6C 3A 20 70 72 69   che-Control: pri
 76 61 74 65 0D 0A 43 6F 6E 74 65 6E 74 2D 54 79   vate..Content-Ty
 70 65 3A 20 74 65 78 74 2F 68 74 6D 6C 3B 20 63   pe: text/html; c
 68 61 72 73 65 74 3D 55 54 46 2D 38 0D 0A 44 61   harset=UTF-8..Da
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 68 74 74 70 3A 2F 2F 77 77 77 2E 67 6F 6F 67 6C   http://www.googl
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 0D 0A 88 90 7E                                    ..~

****above in this frame we got the google site (http protocol) - - - - - - - - - - - - - - - - - - - - - - - - -
----------- ------- ------------ ----------- -------- -------- - - - - - - - - - - - - - - - - - - - - - - - - -

Daniel Peter

# 11 Dec 2010

Hi Vitor

Have a look how Donatien implemented his UMTSStickNetIf, which inherits from a PPPNetIf class - it may be along the lines you want, although you might not need the complexity of the USB interface (there may be some other examples that inherit from PPPNetIf).

The class is here, in Donatien's source.

Regards
Daniel

Edit: I just had a look in the source, there's an AT class as well - seems like everything is there to make a PPP connection via a serially connected GPRS modem.

Daniel Peter

# 12 Dec 2010

Hi Vitor

I had a better look in the code again - there's a GPRSModuleNetIf class which inherits from PPPNetIf and also a Serial interface, so that's probably just want you want (no need to mess around in UMTSStickNetIf which includes the overhead of a USB interface).

Note that there is also a TelitModuleNetIf that inherits from GPRSModuleNetIf as a specific example.

Please let us know how you get on. I'm tempted to see if I can use GPRSModuleNetIf to drive my old T68i GSM mobile phone ...

Regards
Daniel

TK Boonchuk

# 13 Jan 2011

Hi

I try to implement GPRS serial modem and use the NetServices libraries http://mbed.org/users/simon/libraries/NetServices/lic997 where I notice that it has GPRSModuleNetIf module as Daniel mention. I have try with following code

#include "mbed.h"
#include "GPRSModuleNetIf.h"
#include "HTTPClient.h"



GPRSModuleNetIf modem( p28, p27, 9600); //(tx, rx, baud rate)

HTTPClient http;

int main() {
   
    PPPErr pppErr;
    printf("Connecting...\n");
    pppErr = modem.connect("www.apn.provider.com", NULL, NULL);
    
    if (pppErr) {
        printf("Error %d during connection.\n", pppErr);
        return -1;
    }

    HTTPText txt;

    HTTPResult r = http.get("http://mbed.org/media/uploads/donatien/hello.txt", &txt);
    if (r==HTTP_OK) {
        printf("Result :\"%s\"\n", txt.gets());
    } else {
        printf("Error %d\n", r);
    }

    printf("Disconnecting.\n");

    modem.disconnect();

    printf("Disconnected.\n");

    while (1) {

    }

    return 0;

}

But I got errors on compile said "Object of abstract class type "GPRSModuleNetIf" is not allowed: (E322) " Pls anyone could suggest or succeed to GPRS modem using GPRSModuleNetIf.

Regards,

Ronin

Rob Schw

# 25 Jun 2011

I have the same problem, is there any result? Regards, Robert

HM Yoong

# 14 Dec 2011

Any success on your ip connection over gprs? Thank

Klaus Kastler

# 16 Dec 2011

I have the same problem, did anyone solved it? tia

Rene Greiner