I assume that HL7800 is already in USB mode. You can confirm this with AT+KUSBCOMP? command. If it returns “1”, that means device is in USB mode.
Once in USB mode, you will see three ttyACMx ports. Typically, ttyACM0, ttyACM1 and ttyACM2.
USB-ACM0 — AT port
USB-ACM1 — AT/PPP data port
USB-ACM2 — NMEA data port
I will recommend to you ACM1 as your PPP port.
You will also need PPP daemon installed on your host. Check that pppd is available with pppd version
Check that your kernel is built with the ppp module: uname -a; dmesg | grep -i ppp
Before configuring the ppp link, check first you can connect to your ISP (Internet Service Provider) manually. Send manually ATDT123 (or “ATD99**1#” for later releases). You should get a response of “CONNECT or CONNECTED”. Then close the AT link.
Create an /etc/chatscripts/hl78xx-chat file which contains:
ABORT “NO CARRIER”
ABORT “NO DIALTONE”
ABORT “NO ANSWER”
Create an /etc/ppp/peers/hl78xx file which contains:
connect “/usr/sbin/chat -v -t 5 -f /etc/chatscripts/hl78xx-chat”
Launch PPP session with : sudo pppd call hl78xx
If PPP was successfully established, “ifconfig” should show something like:
ppp0 Link encap:Point-to-Point Protocol
inet addr:10.0.0.10 P-t-P:1xx.xx.xx.xx Mask:255.255.255.255
UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1
RX packets:7 errors:0 dropped:0 overruns:0 frame:0
TX packets:7 errors:0 dropped:0 overruns:0 carrier:0
RX bytes:345 (345.0 B) TX bytes:201 (201.0 B)
- If you have access to the embedded Linux shell, the syslog file shows very useful information about the ppp connection.
I have also uploaded PPP chatscripts that you can use.
PPP.7z (422 Bytes)