由于TQ3568 CoreB板卡上測試4G模塊時，需接上USB 4G模塊，如下圖所示：

一、上/掉電4G模塊

系統開機時默認就已經給4G模塊上電了。用戶也可以通過以下命令控制4G模塊的上/掉電。

echo 1/0 > /sys/class/rk_modem/modem_status #0為掉電，1為上電

4G測試程序在/test_utils/4G目錄下，我司提供了SLM750、SLM320，N720三種4G模塊的測試腳本如下圖所示：

用戶可根據實際情況執行測試腳本進行測試，測試前請插上4G天線。

例如測試slm750：只需要執行sh 4G_slm750_TQ3568.sh即可判斷4G功能是否正常：

下面以SLM750模塊為例：

執行效果如下所示：

root@RK356X:/test_utils/4G# sh 4G_slm750_TQ3568.sh
cat: '/sys/bus/usb/devices/7-1:1.1/modalias': No such file or directory
4G_slm750_TQ3568.sh: line 16: echo: write error: Invalid argument

Usage:
kill [options] [...]

Options:
[...] send signal to every listed
-, -s, --signal
specify the to be sent
-q, --queue integer value to be sent with the signal
-l, --list=[] list all signal names, or convert one to a name
-L, --table list all signal names in a nice table

-h, --help display this help and exit
-V, --version output version information and exit

For more details see kill(1).
set dns to 120.80.80.80 221.5.88.88
set def gateway
PING ins-r23tsuuf.ias.tencent-cloud.net (61.241.54.211) from 10.154.10.66 ppp0: 56(84) bytes of data.
64 bytes from 61.241.54.211: icmp_seq=1 ttl=52 time=24.9 ms
64 bytes from 61.241.54.211: icmp_seq=2 ttl=52 time=31.5 ms
64 bytes from 61.241.54.211: icmp_seq=3 ttl=52 time=22.3 ms
64 bytes from 61.241.54.211: icmp_seq=4 ttl=52 time=19.5 ms
64 bytes from 61.241.54.211: icmp_seq=5 ttl=52 time=22.6 ms
64 bytes from 61.241.54.211: icmp_seq=6 ttl=52 time=23.4 ms
64 bytes from 61.241.54.211: icmp_seq=7 ttl=52 time=25.7 ms
64 bytes from 61.241.54.211: icmp_seq=8 ttl=52 time=27.4 ms
64 bytes from 61.241.54.211: icmp_seq=9 ttl=52 time=24.6 ms
64 bytes from 61.241.54.211: icmp_seq=10 ttl=52 time=24.3 ms

--- ins-r23tsuuf.ias.tencent-cloud.net ping statistics ---
10 packets transmitted, 10 received, 0% packet loss, time 17267ms
rtt min/avg/max/mdev = 19.469/24.618/31.501/3.067 ms

二、 報錯

1、 提示XXX目錄找不到

執行腳本后提示找不到xxx/7-1:1.1/modalias目錄，如下圖所示：

原因是4G模塊上電時分配的USB接口不匹配，可以進入/sys/bus/usb/devices目錄下查看是否有類似如下圖所示：

上圖紅框有5-1:1.x多個子集目錄的為內核分配給4G模塊的USB接口目錄，故需要將/test_utils/4G/4G_xxx_TQ3568.sh文件里的目錄修改為對應的5-1:1.x。我們任意選一個5-1：x.x目錄即可，因為這些5-1:1.x目錄里的modies文件所包含的PID、VID值是一樣的。如下圖所示：

2、提示ttyUSB占用：

執行腳本后，報以下錯誤：

Device ttyUSB2 is locked by pid 1366

解決方法：請先執行掉電，重新上電，然后再執行腳本，或者重啟板子。

3、出現超時如：

Script /usr/sbin/chat -s -v -f /etc/ppp/peers/tq_slm750_connect finished (pid 1435), status = 0x0
Serial connection established.
using channel 3
Using interface ppp0
Connect: ppp0 <--> /dev/ttyUSB2
sent [LCP ConfReq id=0x1 ]
rcvd [LCP ConfReq id=0x0 ]
No auth is possible
sent [LCP ConfRej id=0x0 ]
rcvd [LCP ConfAck id=0x1 ]
rcvd [LCP ConfReq id=0x1 ]
sent [LCP ConfAck id=0x1 ]
sent [CCP ConfReq id=0x1 ]
sent [IPCP ConfReq id=0x1 ]
rcvd [LCP DiscReq id=0x2 magic=0xd0c305c0]
rcvd [LCP ProtRej id=0x3 80 fd 01 01 00 07 15 03 2f]
Protocol-Reject for 'Compression Control Protocol' (0x80fd) received
sent [IPCP ConfReq id=0x1 ]
sent [IPCP ConfReq id=0x1 ]
sent [IPCP ConfReq id=0x1 ]
sent [IPCP ConfReq id=0x1 ]
sent [IPCP ConfReq id=0x1 ]
sent [IPCP ConfReq id=0x1 ]
sent [IPCP ConfReq id=0x1 ]
sent [IPCP ConfReq id=0x1 ]
sent [IPCP ConfReq id=0x1 ]
IPCP: timeout sending Config-Requests # 出現這種
sent [LCP TermReq id=0x2 "No network protocols running"]
sent [LCP TermReq id=0x3 "No network protocols running"]
Connection terminated.
Modem hangup
[root@RK356X:/test_utils/4G#

出現這種有可能是天線沒有接好，沒有信號，請檢查一下天線。或者是卡沒有錢，卡上不了網等。