CPU：RK3288
系统：Android 5.1
主板有两个USB接口，一个接USB摄像头，一个接身份证模块。
插入摄像头可以正常打开，再插入身份证模块时，摄像头就会卡主，而且身份证模块无法识别，内核log如下：
[ 208.492045] u*** 3-1.3: new full-speed USB device number 7 using u***20_host
[ 208.571251] u*** 3-1.3: device descriptor read/64, error -32
[ 208.758662] u*** 3-1.3: device descriptor read/64, error -32
[ 208.945433] u*** 3-1.3: new full-speed USB device number 8 using u***20_host
[ 209.024159] u*** 3-1.3: device descriptor read/64, error -32
[ 209.211003] u*** 3-1.3: device descriptor read/64, error -32
[ 209.398208] u*** 3-1.3: new full-speed USB device number 9 using u***20_host
[ 209.810731] u*** 3-1.3: device not accepting address 9, error -32
[ 209.890155] u*** 3-1.3: new full-speed USB device number 10 using u***20_host
[ 210.302863] u*** 3-1.3: device not accepting address 10, error -32
[ 210.303805] hub 3-1:1.0: unable to enumerate USB device on port 3
有时可以识别身份证模块，内核log如下：
[ 743.983805] u*** 3-1.4: new full-speed USB device number 10 using u***20_host
[ 744.062096] u*** 3-1.4: device descriptor read/64, error -32
[ 744.270232] u*** 3-1.4: New USB device found, idVendor=0400, idProduct=c35a
[ 744.270433] u*** 3-1.4: New USB device strings: Mfr=0, Product=0, SerialNumber=0
出现这种现象的原因是2组USB使用同一路供电，当身份证模块插入时，瞬间拉低了USB电源，导致USB供电不足。
两种解决办法：
1、两组USB单独供电；
2、在USB电源上接一个较大的电容，防止电压瞬间被拉低。
CPU：RK3288
系统：Android 5.1
主板有两个USB接口，一个接USB摄像头，一个接身份证模块。
插入摄像头可以正常打开，再插入身份证模块时，摄像头就会卡主，而且身份证模块无法识别，内核log如下：
[ 208.492045] u*** 3-1.3: new full-speed USB device number 7 using u***20_host
[ 208.571251] u*** 3-1.3: device descriptor read/64, error -32
[ 208.758662] u*** 3-1.3: device descriptor read/64, error -32
[ 208.945433] u*** 3-1.3: new full-speed USB device number 8 using u***20_host
[ 209.024159] u*** 3-1.3: device descriptor read/64, error -32
[ 209.211003] u*** 3-1.3: device descriptor read/64, error -32
[ 209.398208] u*** 3-1.3: new full-speed USB device number 9 using u***20_host
[ 209.810731] u*** 3-1.3: device not accepting address 9, error -32
[ 209.890155] u*** 3-1.3: new full-speed USB device number 10 using u***20_host
[ 210.302863] u*** 3-1.3: device not accepting address 10, error -32
[ 210.303805] hub 3-1:1.0: unable to enumerate USB device on port 3
有时可以识别身份证模块，内核log如下：
[ 743.983805] u*** 3-1.4: new full-speed USB device number 10 using u***20_host
[ 744.062096] u*** 3-1.4: device descriptor read/64, error -32
[ 744.270232] u*** 3-1.4: New USB device found, idVendor=0400, idProduct=c35a
[ 744.270433] u*** 3-1.4: New USB device strings: Mfr=0, Product=0, SerialNumber=0
出现这种现象的原因是2组USB使用同一路供电，当身份证模块插入时，瞬间拉低了USB电源，导致USB供电不足。
两种解决办法：
1、两组USB单独供电；
2、在USB电源上接一个较大的电容，防止电压瞬间被拉低。
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