在使用ubuntu配置vscode 的 platformio插件时，常常需要魔法上网来下载依赖

我们可以直接配置好vscode的proxy来下载,也可以用手机热点来下载

然而废了大半天劲配置好网络之后我的platformio却连不上板子

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lsusb
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li@li-MS-7C94:~$ lsusb
Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 008: ID 8087:0032 Intel Corp. AX210 Bluetooth
Bus 001 Device 006: ID 1462:7c94 Micro Star International MYSTIC LIGHT 
Bus 001 Device 004: ID 05e3:0608 Genesys Logic, Inc. Hub
Bus 001 Device 009: ID 0d28:0204 NXP ARM mbed
Bus 001 Device 007: ID 1ea7:0064 SHARKOON Technologies GmbH 2.4GHz Wireless rechargeable vertical mouse [More&Better]
Bus 001 Device 005: ID 1a86:7523 QinHeng Electronics CH340 serial converter
Bus 001 Device 003: ID 05e3:0610 Genesys Logic, Inc. Hub
Bus 001 Device 002: ID 3151:4015 ROYUAN Gaming Keyboard
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

如上所示lsusb显示识别到了我有CH340(即我的esp32开发板)

但是tty串口设备里面却没有

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ls /dev
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li@li-MS-7C94:~$ ls /dev
autofs           input             nvme1n1p6  tty23  tty6       ttyS8
block            kmsg              nvram      tty24  tty60      ttyS9
bsg              log               port       tty25  tty61      
btrfs-control    loop0             ppp        tty26  tty62      udmabuf
bus              loop1             psaux      tty27  tty63      uhid
char             loop10            ptmx       tty28  tty7       uinput
console          loop2             ptp0       tty29  tty8       urandom
core             loop3             pts        tty3   tty9       usb
cpu              loop4             random     tty30  ttyACM0    userfaultfd
cpu_dma_latency  loop5             rfkill     tty31  ttyprintk  userio
cuse             loop6             rtc        tty32  ttyS0      vcs
disk             loop7             rtc0       tty33  ttyS1      vcs1
dma_heap         loop8             sda        tty34  ttyS10     vcs2
dri              loop9             sda1       tty35  ttyS11     vcs3
ecryptfs         loop-control      sda2       tty36  ttyS12     vcs4
fb0              mapper            serial     tty37  ttyS13     vcs5
fd               mcelog            sg0        tty38  ttyS14     vcs6
full             mem               shm        tty39  ttyS15     vcsa
fuse             mqueue            snapshot   tty4   ttyS16     vcsa1
gpiochip0        net               snd        tty40  ttyS17     vcsa2
gpiochip1        ng0n1             stderr     tty41  ttyS18     vcsa3
hidraw0          ng1n1             stdin      tty42  ttyS19     vcsa4
hidraw1          null              stdout     tty43  ttyS2      vcsa5
hidraw2          nvidia0           tty        tty44  ttyS20     vcsa6
hidraw3          nvidia-caps       tty0       tty45  ttyS21     vcsu
hidraw4          nvidiactl         tty1       tty46  ttyS22     vcsu1
hidraw5          nvidia-modeset    tty10      tty47  ttyS23     vcsu2
hpet             nvidia-uvm        tty11      tty48  ttyS24     vcsu3
hugepages        nvidia-uvm-tools  tty12      tty49  ttyS25     vcsu4
hwrng            nvme0             tty13      tty5   ttyS26     vcsu5
i2c-0            nvme0n1           tty14      tty50  ttyS27     vcsu6
i2c-1            nvme0n1p1         tty15      tty51  ttyS28     vfio
i2c-2            nvme0n1p2         tty16      tty52  ttyS29     vga_arbiter
i2c-3            nvme1             tty17      tty53  ttyS3      vhci
i2c-4            nvme1n1           tty18      tty54  ttyS30     vhost-net
i2c-5            nvme1n1p1         tty19      tty55  ttyS31     vhost-vsock
i2c-6            nvme1n1p2         tty2       tty56  ttyS4      zero
i2c-7            nvme1n1p3         tty20      tty57  ttyS5      zfs
i2c-8            nvme1n1p4         tty21      tty58  ttyS6
initctl          nvme1n1p5         tty22      tty59  ttyS7

这么长一串都没有ttyUSB之类的

之后拔插我的esp32开发板然后查看内核日志

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sudo dmesg | tail -n 50
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[  375.204403] usb 1-6.4: USB disconnect, device number 8
[  379.529854] usb 1-6.4: new full-speed USB device number 9 using xhci_hcd
[  379.774322] usb 1-6.4: New USB device found, idVendor=1a86, idProduct=7523, bcdDevice= 2.64
[  379.774329] usb 1-6.4: New USB device strings: Mfr=0, Product=2, SerialNumber=0
[  379.774332] usb 1-6.4: Product: USB Serial
[  379.794042] ch341 1-6.4:1.0: ch341-uart converter detected
[  379.794495] usb 1-6.4: ch341-uart converter now attached to ttyUSB0
[  380.332411] input: BRLTTY 6.4 Linux Screen Driver Keyboard as /devices/virtual/input/input24
[  380.440472] usb 1-6.4: usbfs: interface 0 claimed by ch341 while 'brltty' sets config #1
[  380.441054] ch341-uart ttyUSB0: ch341-uart converter now disconnected from ttyUSB0
[  380.441094] ch341 1-6.4:1.0: device disconnected

原来是被狗草的brltty 服务抢占了我的 CH340 串口设备，导致它刚被识别为 ttyUSB0，立刻又被 brltty 抢走并断开了。

现在直接卸载brltty,然后重启就能解决了

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sudo apt remove brltty # 重启

brltty 是 为盲人或视力障碍用户提供的 braille（盲文）终端支持服务