Android 3G porting "Go"

This article was reproduced from: http://blog.csdn.net/hanmengaidudu/article/details/17028383

Introduction to a development environment

             ubutun 10.04

Content         & nbsp                          ,         &NB SP;
3G module	em820w ( WCDMA)
3G SIM card	China Unicom 3G card
Embedded Linux version	&nbs P            linux-2.6.37
Host development environment

Two main steps

1	Support for adding 3G module drivers (option drivers for USB to serial ports) and PPP network protocols to the Linux kernel
&NBS P                          ,         &NB Sp        2                           &N Bsp                          ,         &NB Sp                          ,         &NB Sp                          ,         &NB Sp	Cross-compiling ppp-2.4.4 source code Copy the two applications PPPD and chat required for dial-up Internet to the Development Board/usr/sbin folder, Write PPP dial scripts WCDMA, Wcdma-chat-connect, wcdma-chat-disconnect and stored in the/etc/ppp/peers directory. Writes DNS to the/etc/resolv.conf file
3	Perform the "PPPD call WCDMA" command to Dial

Three configuration 3G module driver and PPP network protocol stack

First go to make Menuconfig interface

1 Configuring 3G Module drivers

Figure 1

1 First select Device Drivers

Figure 2

2 Entering USB support

Figure 3

Go down to USB support until you find Figure 3 and select USB to serial port

Figure 4

Finally select USB driver for GSM and CDMA modems to this 3G card driver has been added complete

The main additions are driver/usb/serial/option.c and driver/usb/serial/usb_wwan.c.

Two files, although the driver has been added, but this is only a USB-to-serial driver, and can not be used as a network device directly, at this time need to support the PPP network protocol, he will ttyusb* and other devices to simulate the use of network equipment (/dev/ttyusb0<----> PPP0)

2 Adding PPP protocols

Also enter make Menuconfig interface

Figure 5

The first is also to enter the driver configuration Interface Device Drivers

Figure 6

6 Select Network Device Support

Figure 7

7 Choosing PPP

Both drivers and protocols have been configured successfully. The next step is to compile and download to the board.

Log in to Linux, DMESG view kernel printing information

Figure 8

While viewing the/dev/directory, you have created

/dev/ttyusb0,/dev/ttyusb1,/dev/ttyusb2,/dev/ttyusb3,/dev/ttyusb4,/dev/ttyusb5

7 device files such as/DEV/PPP indicate that the kernel correctly identifies the EM820W3G module

Four writing PPP dialing scripts

Because the dial-up script needs to use CHAT,PPPD, such as commands, you need to download ppp-2.4.4

After the download is successful, the first is compile

1 Compiling ppp-2.4.4

./configure

Make CC=ARM-NONE-LINUX-GNUEABI-GCC

After the compilation is successful, the compiled generated chat,pppd,pppdump and other commands are copied to the/usr/sbin directory of the board file system.

2 Writing a dial-up script

Create three files below the/etc/ppp/peers directory of the board file system below

Wcdma,chat-wcdma-connect,chat-wcdma-disconnect

WCDMA Configuration file Contents

Debug

Nodetach

/dev/ttyusb0

115200

Usepeerdns

Noauth

Noipdefault

Novj

Novjccomp

Noccp

Defaultroute

Ipcp-accept-local

Ipcp-accept-remote

Connect '/usr/sbin/chat-s-v-f/etc/ppp/peers/chat-wcdma-connect '

Disconnect '/usr/sbin/chat-s-v-f/etc/ppp/peers/chat-wcdma-disconnect '

Wcdma-chat-connect Configuration file Contents

TIMEOUT 5

ABORT ' NO CARRIER '

ABORT ' ERROR '

ABORT ' Nodialtone '

ABORT ' BUSY '

ABORT ' NO ANSWER '

"' \rat

OK \ratz

Ok \rat+cgdcont=1, "IP", "3GNET", 0,0

Ok-at-ok atdt*99#

CONNECT \d\c

Wcdma-chat-disconnect Configuration file Contents

ABORT "ERROR"

ABORT "Nodialtone"

SAY "\nsending break to the modem\n"

"\k"

"+++ath"

SAY "\ngoodbay\n"

After the dial script is created, it's officially dialed.

PPPD Call wcdma&

(plus the & symbol is mainly because after the successful dial, the program will continue to do not quit, so the use of the background to run, if there are multiple 3G cards may produce multiple ttyusb* device files, and will require multiple WCDMA files at this time can use PPPD call WCDMA1 to PPP dialing for 3G Module 1), PPPD call WCDMA is the role of establishing protocols and generating network interfaces Ppp0

The dial success will appear as shown in printing

Figure 9

After 9 printing appears, add the DNS address vi/etc/resolv.conf in the middle of the/etc/resocv.conf, adding content:

NameServer 202.99.160.68

NameServer 202.99.166.4

Use Ifconfig–a to see if there are ppp0 network devices

Finally, test whether the PPP0 network device can be used

Ping–i ppp0 www.baidu.com

The ability to ping means that the 3G card transplant driver is successful

At this stage the 3G card driver has been ported

Five commissioning

There have been many problems when porting the drive

1 PPPD call WCDMA invocation failed

[Email protected]:~# pppd Call wcdma&

Timeout set to 5 seconds

Abort on (NO CARRIER)

Abort on (ERROR)

Abort on (NO dialtone)

Abort on (BUSY)

Abort on (NO ANSWER)

Send (^MAT^M)

Expect (OK)

At^m^m

Ok

--Got It

Send (^MATZ^M)

Expect (OK)

^m

Atz^m^m

Ok

--Got It

Send (^mat+cgdcont=1, "IP", "3GNET",, 0,0^m)

Expect (OK)

^m

At+cgdcont=1, "IP", "3GNET", 0,0^m^m

ERROR

--Failed

Failed (ERROR)

Connect script failed

Call At+cgdcont=1, "IP", "3GNET", 0,0^m^m

This command failed, in order to test the serial port (command send channel) whether the normal use

Add several other at commands in the middle of the Chat-wcdma-connect

such as OK \rat+cgmi (manufacturer certification request, return module manufacturer information)

OK \RAT+CGSN (view product IMEI serial number)

Then the PPPD call wcdma& Discovery plus the few at commands that are going to execute normally

This means that it is possible that the em820w module does not correctly identify the SIM card

Later I added the OK \rat+csq instruction (view network signal quality) discovery will fail

The preliminary conclusion is that all the at instructions involved in the SIM card will fail, and the other can be executed successfully, which means that the data between the board and the em820w module can be correctly interacted with.

Also due to the failure of the em820w to identify the SIM card, the execution of the instructions failed

Later consulted the relevant personnel, said that my test method is not correct, I use the PPPD program to determine whether certain commands can be executed properly, so that can not be ruled out the PPPD program can resolve the interference caused by the command, so instead of using a more pure method to test

cat/dev/ttyusb0&

echo "AT+CGSN" >/dev/ttyusb0

echo "At+cgmi" >/dev/ttyusb0

echo "AT+CSQ" >/dev/ttyusb0

Observe the response of the serial port and PPPD call WCDMA

So I still think that em820w did not correctly identify the SIM card (but in the future testing still need to choose the right method)

Test the SIM card circuit 5 signal lines regardless of whether there is a SIM card, 5 lines each performance is the same, this means that the SIM card is not recognized, and SIM_VCC and sim_reset the timing of the same, this is not the same as the time series posted on the web, it is obvious that the reset signal is slower than VCC half beat

Figure 10

Figure 10

The hardware engineer modifies the circuit at this time, adding a large capacitor to the sim_reset line, adding a little delay

The PPD call wcdma& is then called

The dial was found to be successful, and a PPP0 network device was present with the Ifconfig–a command

Then test using Ping–i ppp0 www.baidu.com to find that the network is not

Oh, that's a lot.

2 Network not through

Network is not the problem from the beginning to feel sure with the card is not related, it is possible that the network itself, in order to exclude Ethernet port eth0 Interference I conducted the following test

Ifconfig eth0 Down

PPPD Call wcdma&

Ifconfig eth0 up

Ping–i www.baidu.com

After the above toss incredibly network also pass, magical.

Internet query says it is a routing problem caused by dual NIC

Sure enough, when the ppp0 doesn't work, the route command finds the routing table as follows

# route
Kernel IP Routing Table
Destination Gateway genmask Flags Metric Ref useiface
10.64.64.64 * 255.255.255.255 UH 0 0 0 ppp0
192.168.7.0 * 255.255.255.0 U 0 0 0 eth0
Default 192.168.7.1 0.0.0.0 UG 0 0 0 eth0

The routing table is as follows when the Ppp0 pass

# route
Kernel iprouting Table
Destination Gateway genmask Flags Metric Ref use Iface
10.64.64.64 * 255.255.255.255 UH 0 0 0ppp0
192.168.7.0 * 255.255.255.0 U 0 0 0 eth0
Default * 0.0.0.0 U 0 0 0 ppp0

From above can know ppp0 not pass because the default route is eth0, this certainly does not make sense

Six notes

Android 3G porting "Go"