RC7620-1 PPP Data Connection

IoT Modules RC76
1

Hi, I’m trying to setup a PPP connection on a Android box with this modem. I’ve setup CMUX to give myself multiple ports and it all seems to work up to when I go to setup the PPP connection, I get

pppd : Serial connection established.
pppd : using channel 2
pppd : Using interface ppp0
pppd : Connect: ppp0 <–> /dev/ttyGSM2
pppd : sent [LCP ConfReq id=0x4 <asyncmap 0x0> <magic 0x100e78c8> ]
pppd : rcvd [LCP ConfReq id=0x4 <asyncmap 0x0> <magic 0x98ef6e57> ]
pppd : No auth is possible
pppd : sent [LCP ConfRej id=0x4 ]
pppd : rcvd [LCP ConfAck id=0x4 <asyncmap 0x0> <magic 0x100e78c8> ]
pppd : rcvd [LCP ConfReq id=0x5 <asyncmap 0x0> <magic 0x98ef6e57> ]
pppd : sent [LCP ConfAck id=0x5 <asyncmap 0x0> <magic 0x98ef6e57> ]
pppd : sent [CCP ConfReq id=0x2 <deflate 15> <deflate(old#) 15> <bsd v1 15>]
pppd : sent [IPCP ConfReq id=0x2 <compress VJ 0f 01> <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
pppd : rcvd [LCP DiscReq id=0x6 magic=0x98ef6e57]
pppd : rcvd [LCP ProtRej id=0x7 80 fd 01 02 00 0f 1a 04 78 00 18 04 78 00 15 03 2f]
pppd : Protocol-Reject for ‘Compression Control Protocol’ (0x80fd) received
pppd : sent [IPCP ConfReq id=0x2 <compress VJ 0f 01> <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
pppd : sent [IPCP ConfReq id=0x2 <compress VJ 0f 01> <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
pppd : sent [IPCP ConfReq id=0x2 <compress VJ 0f 01> <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
pppd : sent [IPCP ConfReq id=0x2 <compress VJ 0f 01> <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
pppd : sent [IPCP ConfReq id=0x2 <compress VJ 0f 01> <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
pppd : sent [IPCP ConfReq id=0x2 <compress VJ 0f 01> <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
pppd : sent [IPCP ConfReq id=0x2 <compress VJ 0f 01> <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
pppd : sent [IPCP ConfReq id=0x2 <compress VJ 0f 01> <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
pppd : sent [IPCP ConfReq id=0x2 <compress VJ 0f 01> <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
pppd : IPCP: timeout sending Config-Requests
pppd : sent [LCP TermReq id=0x5 “No network protocols running”]
pppd : sent [LCP TermReq id=0x6 “No network protocols running”]
pppd : Connection terminated.
pppd : Modem hangup

I can validate with AT+CGCONTRDP=1 that I’m getting a valid IP, and the same script and setup works fine on a HL7650 module.

Is some additional configuration required?

2

Does PPP work without using CMUX?
why don’t you use AT!SCACT to establish data connection as it seems easier?

3

CMUX does not appear to make any difference.

How does AT!SCACT work? The documentation is unclear on what this command exactly does.
What sort of connection does it make? How do I use it? What protocol do I use?

4

Does PPP work without using CMUX?

For AT!SCACT, if you have install the GobiNet driver in Android RIL SDK, you can type the following to establish data connection:

AT+CGDCONT=1,“IP”,“APN”
AT!SCACT=1,1

You might also see here on how to use ndc command to let upper layer in Android to access data connection:

5

No, PPP does not work without CMUX. Exactly the same error.

So if I send
AT!SCACT=1,1
I should expect a data interface over QMI?

6

If you want to try PPP, you can try wvdial tool in Ubuntu Linux PC first.
I tried on Ubuntu14 with wvdial, I don’t see problem.

BTW, for AT!SCACT command, you can also verify in Ubuntu PC first.

7

Interesting, the AT!SCACT=1,1 command gives a CMEE error of 30
This would be no network? Yet I have a decent reception power and get an IP and network info.
Do you need to configure anything else?

I assume when you write
AT+CGDCONT=1,“IP”,“APN”
I should replace the APN with my actual APN?

8

yes, you need to use your actual APN of your sim card

9

Interesting, it looks like after sending the command, I disconnect from the network and that’s why it fails.
This is also why CGDATA fails with the same behaviour, though it shouldn’t really respond with “CONNECTED” and should respond with “NO CARRIER” .

10

seems your sim card has some problem.
Here i don’t see problem to dial up with wvdial in Ubuntu 14