ppp on pic18

puppie7777 · Joined: 09 Jun 2004 Posts: 25 Location: Monterey, CA

my question maybe not so relative to this forum, but i hope if there are some people familar with it can help.

i am building ppp tcp/ip on pic18 thr GPRS modem. my ppp connection has been established already, i can get the ACK of ip and DNS, but i tried to ping to any server with sending a ICMP packet to GPRS modem, the modem didnt give me any echo response.

any suggestion is highly preciated!

Thx!

Darren Rook · Joined: 06 Sep 2003 Posts: 287 Location: Milwaukee, WI

Some ISPs and servers block ping because it's a security risk. Maybe that's your problem?

puppie7777 · Joined: 09 Jun 2004 Posts: 25 Location: Monterey, CA

Thx for your kind concerning. but the "Trick" is that i have try those public ones such like yahoo.com which can be ping from any MS DOS client. still got he same problem.

Darren Rook · Joined: 06 Sep 2003 Posts: 287 Location: Milwaukee, WI

Well, I don't know what anyone can do here to help you. I've written an IP stack with PPP so I know a lot, but you really havent given us any information to help you.

puppie7777 · Joined: 09 Jun 2004 Posts: 25 Location: Monterey, CA

Thanks so much Darren!
my current problem in details is that now i dont know how to link up the ip with the ppp, my GPRS modem is connected thru RS232 to pic18, i have established the GPRS connection thru AT commands, and finished all the LCP-PAP-IPCP handshakings, so from the Rx pin of MCU, i can finally get the ACK of ipcp as following:
7E
FF 7D 23 80 21 7D 22 7D 21 7D 20 7D 30 7D 23
7D 26 AC 7D 36 3A 7B 81 7D 26 CA 4F 7F A6 3F 67
7E
Then, i tried to send an ICMP packet or IP packet data to Tx PIN, but the GPRS modem didn't give me any response. Did i miss anything here?

one more question is, i try to use the TCP/IP stack from "TCP/IP LEAN"(second edition) written by Jeremy Bentham, but those coding seems quite messy. those codes for SLIP or Ethernet NIC(i no need to use) ... ... confuses me so much... ...

xpercad · Joined: 27 Jun 2004 Posts: 12 Location: MÉXICO

Hi puppie7777,

Did you finally solve the TCP/IP with PPP project on the PIC18 with the GPRS modem ??? I am about to start development for a similar project and would very much like to hear some feedback from somebody who has been around the block.

Feedback from anybody will be highly apreciated.

Regards,

Aaron

Guest · Posted: Mon Aug 02, 2004 8:48 am

What type of GPRS modem you use? I use Wavecom adapters with IP stack included so I am able e.g. to send an e-mail with a plain at#sendmail command (FTP is also supported by AT commands).

xpercad · Joined: 27 Jun 2004 Posts: 12 Location: MÉXICO

I am using a Siemens XT55 (GSM/GPRS + GPS) and it does not include a TCP/IP Stack. There is a big price advantage using this integrated module (GPS is included) but the downside is that there is no TCP/IP Stack.

I have very little time for development and my big question is how long will it take me to have the stack operational. The TCP/IP services I need are PPP (to establish the link) and basicaly TCP and UDP for information exchange.

Regards,

Aaron

Guest · Posted: Mon Aug 02, 2004 9:49 am

Price advantage? I bought Wavecoms for cca. $100 each Smile

How much the XT55 costs? (Wavecom has something with GPS and IP stack for cca. $150 but I don't know the exact type number...)
The time for implementing PPP is depended upon your original source Smile

xpercad · Joined: 27 Jun 2004 Posts: 12 Location: MÉXICO

I can not disclose exact price figures for the Siemens XT55 beacuse I have a NDA with them. What I can tell you is that their pricing is very attractive. The Wavecom module that includes the GPS is not intended for the North American market.

If you are interested in the Siemens modules you should contact:

Shawn Sanderson
Sales Manager
Wireless Modules
Direct: (858) 521-3398
Mobile: (858) 776-0432
Fax: (858) 521-3105
Email: shawn.sanderson@siemens.com
www: http//www.siemens-mobile.com/wm