查看F1C的源代码

=== 4G ===

* [[EMTC]]
* [http://oldask.openluat.com/article/37 Air720模块Linux USB驱动以及PPP拨号说明]
* [http://oldask.openluat.com/article/79 Air720模块在linux设备上的RNDIS网卡使用]


[http://wiki.jackslab.org/EMTC#AT Air724 AT 接口]


入网不成功，可能导致枚举 usb 设备失败:

<source lang=bash>
[    7.780813] usb 1-1: new high-speed USB device number 2 using musb-hdrc
[    7.940764] usb 1-1: device descriptor read/64, error -71
[    8.210885] usb 1-1: device descriptor read/64, error -71
[    8.480803] usb 1-1: new high-speed USB device number 3 using musb-hdrc
[    8.630701] usb 1-1: device descriptor read/64, error -71
[    8.900700] usb 1-1: device descriptor read/64, error -71
[    9.020862] usb usb1-port1: attempt power cycle
[    9.510701] usb 1-1: new high-speed USB device number 4 using musb-hdrc
[    9.950713] usb 1-1: device not accepting address 4, error -71
[   10.100707] usb 1-1: new high-speed USB device number 5 using musb-hdrc
[   10.540723] usb 1-1: device not accepting address 5, error -71
[   10.546757] usb usb1-port1: unable to enumerate USB device
</source>

去除 sim 卡一样的错误 log，插入一个新卡一样，换 4G sim 卡一样的现象

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