GPRS jibberish - PPP data

Wireless & IoT
1

Greetings to you all.

It seems that nobody knows what to do when once connected to GPRS network after receiving PPP data such as:

CONNECT
~ }#Ŕ!}!} } }2}#}$Ŕ#}!}$}%Ãœ}"}&} }*} } g}%~~ }#Ŕ!}!} } }2}#}$Ŕ#}!}$}%Ãœ}"}&} }*}

I also do not have a clue what to do next.

Is there anyone in this WORLD who could tell us all what is the next step?

I am connected to Nokia 6230i through HyperTerminal and this is my AT command list:

AT&FV1&D2&S0&C1S0=0                   
OK  

ATS7=60+DS=3,0;&K3
OK

ats0=0
OK

AT&FV1&D2&S0&C1S0=0
OK

ATS7=60+DS=3,0;&K3
OK

ATD*99***1#

After that I receive this:

CONNECT
~ }#Ŕ!}!} } }2}#}$Ŕ#}!}$}%Ãœ}"}&} }*} } g}%~~ }#Ŕ!}!} } }2}#}$Ŕ#}!}$}%Ãœ}"}&} }*}
} g}%~~ }#Ŕ!}!} } }2}#}$Ŕ#}!}$}%Ãœ}"}&} }*} } g}%~~ }#Ŕ!}!} } }2}#}$Ŕ#}!}$}%Ãœ}"}&
} }*} } g}%~~ }#Ŕ!}!} } }2

… and so on.

WHAT NEXT? Eventually I will use PIC microcontroller to do all the stuff, but really, how do people build stuff such as real-time tracking if this is impossible to figure out? I just want to transfer some text like “HELLO WORLD” :smiley:

I have an online web server which will receive data from my “device” but it seems everyone is stuck at this point?

Best regards,

Muris Trax

2

PPP has a bunch of sub-protocols that you’ll need to deal with in order to get an actual IP connection. What’s going on is that the phone is emulating a Hayes modem and a dialup ISP. You need to get past all that in order to get an IP packet to the GPRS network.

I guess you’ll need rfc1661 for the basic outline of PPP, rfc1332 for IPCP (to tell PPP you’re making an IP connection instead of, say, an X.25 connection), and possibly rfc1334 for PAP (sending a password — completely pointless, but your device might require it anyway). That’s a lot of RFCs, but the nice thing is that since they’re internet standards instead of ISO standards, they’re all freely available.

This is all unnecessarily baroque and complex, but it seems to be the only way to do it. I really wish there were a way to get to the GPRS interface more directly instead of going through all this emulated rigamarole, but I haven’t seen an implementation that does. :frowning: Of course, once you get the IP connection set up, you still need to deal with the usual IP issues — hostname resolution (DNS), and TCP, and whatever protocol you’re running on top of TCP (SMTP, HTTP, etc.). If you can, I suggest not trying to write all this yourself.

Here’s an example of my laptop setting up a connection to my cell phone, just to give an example of the PPP setup conversation:

23:40:24: Write : AT\13
23:40:24: Matched : OK\13\10
23:40:24: Write : AT+CGMI\13
23:40:24: Matched : Nokia
23:40:24: Write : AT&FE0V1&D2&S0&C1S0=0+IFC=0,2\13
23:40:24: Matched : OK\13\10
23:40:26: Write : AT+CBST=14,0,1\13
23:40:26: Matched : OK\13\10
23:40:26: Dialling *99#
23:40:26: Write : ATX5DT*99#\13
23:40:26: Matched : CONNECT
23:40:30: Serial connection established.
23:40:31: Connect: ppp0 <--> /dev/cu.Bluetooth-Modem
23:40:32: sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x8be97632> <pcomp> <accomp>]
23:40:32: rcvd [LCP ConfRej id=0x1 <magic 0x8be97632> <pcomp> <accomp>]
23:40:32: sent [LCP ConfReq id=0x2 <asyncmap 0x0>]
23:40:32: rcvd [LCP ConfAck id=0x2 <asyncmap 0x0>]
23:40:32: rcvd [LCP ConfReq id=0x0 <auth pap> <mru 1500> <asyncmap 0xa0000>]
23:40:32: No auth is possible
23:40:32: lcp_reqci: returning CONFREJ.
23:40:32: sent [LCP ConfRej id=0x0 <auth pap>]
23:40:32: rcvd [LCP ConfReq id=0x1 <mru 1500> <asyncmap 0xa0000>]
23:40:32: lcp_reqci: returning CONFACK.
23:40:32: sent [LCP ConfAck id=0x1 <mru 1500> <asyncmap 0xa0000>]
23:40:32: sent [IPCP ConfReq id=0x1 <compress VJ 0f 01> <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns3 0.0.0.0>]
23:40:32: rcvd [IPCP ConfReq id=0x0 <addr 10.6.6.6>]
23:40:32: ipcp: returning Configure-ACK
23:40:32: sent [IPCP ConfAck id=0x0 <addr 10.6.6.6>]
23:40:33: rcvd [IPCP ConfRej id=0x1 <compress VJ 0f 01>]
23:40:33: sent [IPCP ConfReq id=0x2 <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns3 0.0.0.0>]
23:40:33: rcvd [IPCP ConfNak id=0x2 <addr 10.169.61.47> <ms-dns1 66.94.9.120> <ms-dns3 66.94.25.120>]
23:40:33: sent [IPCP ConfReq id=0x3 <addr 10.169.61.47> <ms-dns1 66.94.9.120> <ms-dns3 66.94.25.120>]
23:40:33: rcvd [IPCP ConfAck id=0x3 <addr 10.169.61.47> <ms-dns1 66.94.9.120> <ms-dns3 66.94.25.120>]

You can see it dialling the (fake) modem, then doing PPP negotiations (each line corresponds to one PPP packet). At the end of this, the host knows what IP address it’s been assigned and knows what DNS servers to use, and can start sending IP packets across the link.

3

Thanks for the reply.

So, I will stop surfing the web for some magic “AT” commands to send data over internet through GPRS connection on conventional GSM telephone such as Nokia.

I have found this though: http://www.gsm-modem.de/gprs-http_.html

It is some kind of GPRS modem with built-in tcp/ip stack, ppp negotiation and other required thingies. Well, someday… someday :smiley:

Good luck

4

hi Muris Trax

Have u completed the data transfer thru gprs using PIC if so please let me know the process.i am struck with this probs…

5

No I haven’t. I gave up, and went for GSM GPRS modules that have built-in TCP/IP stack and Easy GPRS AT commands. Try SIMCOM 300Z module.

6

hi thx for reply…i am using PIC-GSM olimex board (SIMCOM 300dz) module,can u please help me how to send and receive data using the module.wat set of commands to use and the flow…

7

Look at the FAQ on this page http://www.madeeasykits.com/Faqs.asp titled ‘How do I make a GPRS connection and send an HTTP Request?’