HL7692 linux networking activation


#1

Hi,

I have been sucessfully using an HL8548 (3G) module with an ARM processor running linux.
I am now trying an HL7692 (4G) module and have not worked out how to get it to provide a network connection for linux.

The HL8548 was configured to provide a CDC-ECM port (AT+KUSBCOMP=2).
This appeared under linux as eth0 and I could activate it using “ifup usb0” from linux and AT+XCEDATA=1,0 to the HL8548.

The HL7692 does not provide CDC-ECM, instead it provides NCM or MBIM.
These appear under linux as wwan0, wwan1 etc
The AT+XCEDATA command does not exist (fair enough because it is described as Establish ECM Data Connection, and ECM is not being used)
If I do “ifup wwan0” linux attemps to get an address using DHCP but fails.

Listening on LPF/wwan0/00:00:11:12:13:14
Sending on LPF/wwan0/00:00:11:12:13:14
Sending on Socket/fallback
DHCPDISCOVER on wwan0 to 255.255.255.255 port 67 interval 6
DHCPDISCOVER on wwan0 to 255.255.255.255 port 67 interval 10
DHCPDISCOVER on wwan0 to 255.255.255.255 port 67 interval 11
DHCPDISCOVER on wwan0 to 255.255.255.255 port 67 interval 16
DHCPDISCOVER on wwan0 to 255.255.255.255 port 67 interval 12
DHCPDISCOVER on wwan0 to 255.255.255.255 port 67 interval 6
No DHCPOFFERS received.
No working leases in persistent database - sleeping.

I suspect that I need to send something similar to the AT+XCEDATA command to the HL7692, but I haven’t spotted it in the AT Command Interface Guide.

Any suggestions?


#2

Hi,

Yes the HL7692 does not support the CDC-ECM interface (unfortunately given how easy it is to use) and consequently the xcedata command does not work. With a host system and an external IP stack other than PPP you do need to use the NCMHL7 NCM interface for AT&T.docx (118.8 KB)
which is a bit of a hack and not very clean, it is described in the attached document.

Regards

Matt


#3

Thanks Matt,

That worked for me.
Should I have been able to work that out for myself from information on the Sierra Wireless website?
Unless there’s some document that I have missed I can’t see how I would have worked out the AT+XDATACHANNEL=1,1,"/USBCDC/0","/USBHS/NCM/0",2,1
and
AT+CGDATA=“M-RAW_IP”,1

By the way I couldn’t see how to send the commands through the modem port under linux, so I sent them through /dev/ttyACM1 (one of the AT ports) - but it did work.

Tim


#4

Tim,

The at+xcedata command has been removed from newer WP76xx command manuals which effectively states it is not supported, it was included initially in older versions just because it was read across from other commands sets without being verified properly. The command might react because of legacy code in the firmware but it will not do anything.

To give you a hard answer to your question, no it is not specifically stated anywhere it is more implied, which is not great I agree for customers who have used it on the HL8 previously where it was implemented.

Regards

Matt


#5

Hi Matt,

Thanks very much for your help.

It wasn’t so much the lack of the AT+XCEDATA command that I struggled with - though, as you said, it would have been really nice if CDC-ECM had “just worked” the same way as the HL8.

Rather it was working out what I needed to do instead, i.e. could I have found the information that you provided in the HL7 NCM interface document without asking here on the forum?

Regards,

Tim


#6

Tim,

Ah right, no it is not in any official documentation anywhere or on the forum to my knowledge so you did need to ask the question. Typically speaking the HL’s are generally used with their embedded IP stacks or using PPP dial up, using the network interface is one of the lesser used mechanisms.

Regards

Matt