Linux已经识别出数据卡对应的端口为 ttyUSB0和ttyUSB1 ，但是发送AT命令无法接收到终端响应（Windows下是正常的）.
另外，通过 cat /dev/ttyUSB0 也无法显示发送和接收的数据. 但是我通过write函数写的数据返回是成功的。
yaffs: Attempting MTD mount on 31.3, "mtdblock3"
yaffs: auto selecting yaffs2
yaffs: restored from checkpoint
yaffs_read_super: isCheckpointed 1
VFS: Mounted root (yaffs filesystem) on device 31:3.
Freeing init memory: 168K
usb 1-1: New USB device found, idVendor=12d1, idProduct=14fe
usb 1-1: New USB device strings: Mfr=2, Product=1, SerialNumber=0
usb 1-1: Product: HUAWEI Mobile
usb 1-1: Manufacturer: HUAWEI
usb 1-1: configuration #1 chosen from 1 choice
option 1-1:1.0: GSM modem (1-port) converter detected
usb 1-1: GSM modem (1-port) converter now attached to ttyUSB0
option 1-1:1.1: GSM modem (1-port) converter detected