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Terms:
DC: Dialing Control
The overall 3G dial
process is designed as a module called DC, and depicted as a timing
synchronization (to handle race condition) , dialing control, modem
replacement, SIM card replacement, pin code verification, error handling,
dial-on-demand.
The 3G logistic schema of dialing function is
designed to base on the hot-plug mechanism of MR3306a USB subsystem to have 3G dialer behavior dynamically and automatically handle
3G connection to ISP 3G network per crond cycle(i.e. the period
set in crontab).
When the 3G is running, then the cron daemon will
periodically call the function, cron_3g _start,
a entry function of dialing control (DC), to maintain 3g connection. This is also the auto re-start
mechanism, and the 3g connection
will be initiated by cron daemon when no any 3G connection.
There
are 3 major parts in 3G
application, i.e. device management, dialer, budget control.
The device
management, Our design in it mainly rely on 3 mechanism:
1. the
device detection
To look into the kernel for 3G /HSPA device id and product id to make sure
what device is discovered..
2. USB
subsystem hot-plug mechanism
udevd handles all device discovery, we will
have working rules to tell what device
2.1
plug-in detection
serialize the signaling from kernel,
exclusive successive signal.
according to the signaling event, we define
the handling routine.
2.2
unplug detection
according to the signaling event, we
define the handling routine.
shut down 3G /HSPA service.
3.
install device driver:
Because
the 3G modem in the market is
often being in the style of zeroCD, i.e. when the device insert into USB
connector, then it is be identified as a storage device, like CDROM. When it is
a storage mode, the usbserial driver cannot scratch it, so the driver
installation is failed.
This is due to he fact that device has usb storage
to store windows driver etc. as well as modem. Due to this Linux kernel drivers
get confused. While Huawei seems to be working to get the appropriate
modification in kernel drivers done, as of now it is not there. One way to solve is using 'usb_modeswitch' program to
switch USB gear from the storage mode to the modem mode. A utility called mode
switch can do that.
driver:
usbserial, cdcam, airprime, option,
sierra, or customized
USB_ModeSwitch
is a mode switching tool for controlling "flip flop" (multiple
device) USB gear.
Configuration
-----------------
mainly pppd profile and chat script to dial up the internet
we should know (1)3G operator server's basic settings and
(2)modem device settings.
such
as,
crtscts
modem
noauth
usepeerdns
defaultroute
noipdefault
noccp
nobsdcomp
novjmodem
port: /dev/ttyUSB0, baud rate:460800, AT command string
Statistics
- BC settings and policy rules of
time and data,
remaining budget, summated elapsed
time(elapse base),
download/upload/DL+UL(data base)
Troubleshooting
1.
remote debugging
2. manual mode --> pppd debug mode to look into --> embedded codes to verify what happen and resolve
1. Dialing Control(DC)
1.1 no any modem device is detected
1.2 no dial process is initiated.
1.3 already have dial process is
on-going,
1.4 pin code is wrong
1.5 no budget is over, except that
budget is reset during the same billing period.
2. PIN code protection verification(VPC)
what we do is to exam PIN code consistence with both user input side and
SIM card side, just a correction verification.
There are 2 times of opportunities to verify the pin code consistence. The
VPC issue a command to SIM card, then SIM card reply the message according to
its status.
3.hot-plug -udevd
If you do hot-plug the 3G
modem, please give it a period of 5~8 seconds(suggestion) because it need some time to shut down all
wan service.
1.
Cyclically monitor 3g device exists
Monitor on-line is a mechanism to maintain 3g connection status, by means of cron schedule. The hot-plug mechanism is not function well
in all 3G modems.
Some is good, and some is function bad. It needs detection on schedule when
every cycle. When a device with abnormal hot-plug behavior, then we have to do
clean action to let start 3g
go. i.e. remove garbage flag,
information, pppd process, and drivers.
The function of cron 3g
automatically restart when 3g
disconnected is relying on system hot-plug mechanism.
Initially, the cron 3g
process will be blocked outside the protection area of 3g dial process, but the successive cron 3g process has its own short life cycle to
die. In general, it have good behavior, so you see the alias from
"ps" command. But it still have its limitation when overall system is
confusing and out of controlled. After
that, the cron daemon will periodically call cron 3g
4. device existence detection
Please see the file /var/3gs/simlog.
The file tell you some basic action when call comgt.
1: SIM READY -- pin code protection enable and verification OK.
2. Netowrk registrate to some local 3G ISP network.
3. signal quality
The function of cron 3g
automatically restart when 3g
disconnected is relying on system hot-plug mechanism.
Initially, the cron 3g
process will be blocked outside the protection area of 3g dial process, but the successive cron 3g process has its own short life cycle to
die. In general, it have good behavior, so you see the alias from
"ps" command. But it still have its limitation when overall system is
confusing and out of controlled. After
that, the cron daemon will periodically call cron 3g
If you do hot-plug the 3G
modem, please give it a period of 5~8 seconds(suggestion) because it need some time to shut down all
wan service.
The variables:
wan_3g _last_setPincode_Error:
0: Normal
correct pincode
1: Wrong PIN Code
wan_3g _connection_state:
0: network connected
1: dial failure code
2: unreachable host or
network
3: gateway ip address
not found
4: 3G /HSDPA usb device not ready
5: iface $run_if
connection has ready
6: plug-out or doesn't
exist on USB port
7: plugged in
8: force stop 3G
9: Wrong PIN Code
10: No iface $run_if
available
11: time-out
wan_3g _err_pincode_count
pin remaining attempt
number
LED message lights:
Start 3G by auto/manual
mode
2.
Manual start
2.1 Networking settings/start mode
Scenario
1: user select what start mode is used auto start or manual start
Function name:
Start_by_mode
0: automatically start
1:
manually start
Logistical:
Just only save parameters into meta when user select manually start
If
user select automatically start mode, then it is work as original designed
function.
2.2 WEB UI Information/manual start/manual stop
This is scenario is working in the manual mode only.
Scenario
2: manually start/stop 3G from
information page when in manual mode
this case does
not allow automatic mode function work.
2.3 Hardware button
scenario
3: user press the button on box. the hard push button is a toggle switching 3g service on or off
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