GPRS与PPP(GPRS模块虚拟成网口)


一、参考网址

  1、linux下GPRS模块ppp拨号上网

  2、关于PPP拨号 和 AT指令实现GPRS模块联网的疑问

  3、ppp 完全理解(一)

  4、GPRS模块在Linux平台上ppp拨号上网总结与心得

  5、GPRS模块--PPP手动拨号

  6、脚本示例

  7、实现4G模块EC20在linux系统下的拨号上网

二、技术细节

  1、ppp拨号的必要条件

    

   2、pppd执行需要用到动态链接库

    libpcap.so  libpcap.so.1  libpcap.so.1.8.1

    在buildroot目录下:output/target/usr/lib

三、实现步骤

  1、内核编译添加支持ppp网络设备驱动, 截图如下:   

    执行脚本:linux/BSP/A7/kernel/A7-linux-src-4.14/build.sh

    

    

     生成的内核zImage存放目录:linux/BSP/A7/kernel/A7-linux-src-4.14/kernel-output/zImage   或 linux/BSP/A7/kernel/A7-linux-src-4.14/arch/arm/boot/zImage

     用file命令查看zImage文件信息,如下:

zImage: Linux kernel ARM boot executable zImage (little-endian)

  2、buildroot下编译pppd和chat 应用程序

     执行脚本:linux/BSP/ROOTFS/buildroot/v2017.08/build.sh, 截图如下:

    

    

     生成的文件目录:  linux/BSP/ROOTFS/buildroot/v2017.08/output/target/usr/sbin, 其有如下可执行程序: chat   pppd   pppdump    pppoe-discovery   pppstats

     把这些程序拷贝到开发板的相应目录下(/usr/sbin),并添加可执行权限

     把生成的动态链接库(output/target/usr/lib)拷贝到相应目录下/usr/lib,因为执行pppd会用到:libpcap.so  libpcap.so.1  libpcap.so.1.8.1

  3、增加拨号脚本

    1)在开发板添加新目录:/etc/ppp/peer

    2 ) 通过hfs,把移远提供的脚本(linux-ppp-scripts_V1.2文件夹)拷贝到/etc/ppp/peer目录下:

      quectel-ppp   quectel-chat-connect   quectel-chat-disconnect   quectel-ppp-kill  quectel-pppd.sh   readme

      把ip-up脚本拷贝到/etc/ppp目录下

      所有脚本增加可执行权限

  4、搭建硬件测试环境

    1)断开RTU集中器的ARM与GPRS模块的串口连接

    2)编写一个小程序拷贝到RTU集中器上,可以控制GPRS模块的电源

    3)把gprs模块的串口与A7开发板的TX3、RX3和GND相连

      4)控制GPRS模块上电

  5、修改脚本的串口名称或者APN

    1) 修改脚本quectel-ppp中的串口名称为/dev/ttymxc2(实际连接串口名称)

      开发板串口测试,在开发板上输入如下命令:

            stty -F /dev/ttymxc2 115200

            echo Test > /dev/ttymxc2   (测试发送,在电脑上用串口调试器监视)

            cat /dev/ttymxc2   (测试接收)

    2) 在 quectel-chat-connect 脚本里可修改APN

  6、运行及测试

    1)运行命令:

pppd call quectel-ppp &

    2)运行结果,如下截图:

[root@fonda peers]# pppd call quectel-ppp &
[root@fonda peers]# pppd options in effect:
debug        # (from /etc/ppp/peers/quectel-ppp)
nodetach        # (from /etc/ppp/peers/quectel-ppp)
dump        # (from /etc/ppp/peers/quectel-ppp)
noauth        # (from /etc/ppp/peers/quectel-ppp)
user test        # (from /etc/ppp/peers/quectel-ppp)
password ??????        # (from /etc/ppp/peers/quectel-ppp)
remotename 3gppp        # (from /etc/ppp/peers/quectel-ppp)
/dev/ttymxc2        # (from /etc/ppp/peers/quectel-ppp)
115200        # (from /etc/ppp/peers/quectel-ppp)
lock        # (from /etc/ppp/peers/quectel-ppp)
connect chat -s -v -f /etc/ppp/peers/quectel-chat-connect        # (from /etc/ppp/peers/quectel-ppp)
disconnect chat -s -v -f /etc/ppp/peers/quectel-chat-disconnect        # (from /etc/ppp/peers/quectel-ppp)
nocrtscts        # (from /etc/ppp/peers/quectel-ppp)
modem        # (from /etc/ppp/peers/quectel-ppp)
hide-password        # (from /etc/ppp/peers/quectel-ppp)
novj        # (from /etc/ppp/peers/quectel-ppp)
novjccomp        # (from /etc/ppp/peers/quectel-ppp)
ipcp-accept-local        # (from /etc/ppp/peers/quectel-ppp)
ipcp-accept-remote        # (from /etc/ppp/peers/quectel-ppp)
ipparam 3gppp        # (from /etc/ppp/peers/quectel-ppp)
noipdefault        # (from /etc/ppp/peers/quectel-ppp)
ipcp-max-failure 30        # (from /etc/ppp/peers/quectel-ppp)
defaultroute        # (from /etc/ppp/peers/quectel-ppp)
usepeerdns        # (from /etc/ppp/peers/quectel-ppp)
noccp        # (from /etc/ppp/peers/quectel-ppp)
abort on (BUSY)
abort on (NO CARRIER)
abort on (NO DIALTONE)
abort on (ERROR)
abort on (NO ANSWER)
timeout set to 30 seconds
send (AT^M)
expect (OK)
AT^M^M
OK
 -- got it

send (ATE0^M)
expect (OK)
^M
ATE0^M^M
OK
 -- got it

send (ATI;+CSUB;+CSQ;+CPIN?;+COPS?;+CGREG?;&D2^M)
expect (OK)
^M
^M
Quectel^M
EC20F^M
Revision: EC20CEHCR06A02M1G^M
^M
SubEdition: V03^M
^M
+CSQ: 24,99^M
^M
+CPIN: READY^M
^M
+COPS: 0,0,"CHINA MOBILE",7^M
^M
+CGREG: 0,1^M
^M
OK
 -- got it

send (AT+CGDCONT=1,"IP","3gnet",,0,0^M)
expect (OK)
^M
^M
OK
 -- got it

send (ATD*99#^M)
expect (CONNECT)
^M
^M
CONNECT
 -- got it

Script chat -s -v -f /etc/ppp/peers/quectel-chat-connect finished (pid 298), status = 0x0
Serial connection established.
using channel 1
Using interface ppp0
Connect: ppp0 <--> /dev/ttymxc2
sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x4827b4fe> <pcomp> <accomp>]
rcvd [LCP ConfReq id=0x0 <asyncmap 0x0> <auth chap MD5> <magic 0x71f3af97> <pcomp> <accomp>]
sent [LCP ConfAck id=0x0 <asyncmap 0x0> <auth chap MD5> <magic 0x71f3af97> <pcomp> <accomp>]
rcvd [LCP ConfAck id=0x1 <asyncmap 0x0> <magic 0x4827b4fe> <pcomp> <accomp>]
rcvd [LCP DiscReq id=0x1 magic=0x71f3af97]
rcvd [CHAP Challenge id=0x1 <4003ccc71a6535e1f787fb38456a6f5e>, name = "UMTS_CHAP_SRVR"]
sent [CHAP Response id=0x1 <2ebf1a489416e080a2dc61cc525fae82>, name = "test"]
rcvd [CHAP Success id=0x1 ""]
CHAP authentication succeeded
CHAP authentication succeeded
sent [IPCP ConfReq id=0x1 <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
rcvd [IPCP ConfReq id=0x0]
sent [IPCP ConfNak id=0x0 <addr 0.0.0.0>]
rcvd [IPCP ConfNak id=0x1 <addr 10.34.181.249> <ms-dns1 120.196.165.7> <ms-dns2 221.179.38.7>]
sent [IPCP ConfReq id=0x2 <addr 10.34.181.249> <ms-dns1 120.196.165.7> <ms-dns2 221.179.38.7>]
rcvd [IPCP ConfReq id=0x1]
sent [IPCP ConfAck id=0x1]
rcvd [IPCP ConfAck id=0x2 <addr 10.34.181.249> <ms-dns1 120.196.165.7> <ms-dns2 221.179.38.7>]
Could not determine remote IP address: defaulting to 10.64.64.64
local  IP address 10.34.181.249
remote IP address 10.64.64.64
primary   DNS address 120.196.165.7
secondary DNS address 221.179.38.7
Script /etc/ppp/ip-up started (pid 301)
Script /etc/ppp/ip-up finished (pid 301), status = 0x0

  3)ifconfig 查看虚拟网口

  

 

  4)使用ps查看pppd守护进程

 

   5) ping外网测试

 

 四、多路串口复用

  1、必备资料

    1)源码:gsm0710muxd_bp.c和Makefile

    2)说明文档:《Quectel_Android&Linux_CMUX_Driver_User_Guide_V1.1.pdf》

  2、目的

    用1个物理串口,模拟出多个串口;如1路串口用于ppp拨号,另1路串口用于AT指令测试(检测信号强度、IMEI、ICCID和模块信息)

  3、步骤

    1)修改Makefile, 使用交叉编译器编译,生成可执行程序gsm0710muxd_bp

    2)执行程序:/usr/bin/gsm0710muxd_bp -s /dev/ttymxc7 -b 115200 -n 3

    3)在/dev/chn目录下会生成1、2、3,如下图:

      

 

     4)多路串口复用OK

 

  


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