posted by wap, platform: iPhone
要带供电隔离的
5口以上
给树莓派4用 买了两个都是usb 反向充电 导致只要插上usb hub树莓派就不能启动
抓狂

posted by wap, platform: MAC OS X
没看懂你说的是把树莓派的电源插在USB HUB上，还是把USB HUB插在树莓派上。如果是前者的话，你先考虑一下功率和供电方式。你要同时使用几个树莓派。一个树莓派4B的电源是5V3A,所以功率是15W。你要同时用5个口接树莓派。那就至少要75W。所以怎么想也应该是220V电压直接供电，不能用电脑的USB接口了吧？如果非得要USB接口供电还要保持稳定，至少是USB Type-C接口才行，可以提供100W供电。


如果是后者的话，你可能说的是单台树莓派。这样的话考虑一下树莓派的USB接口输出功率。树莓派的USB接口2.0的标准是500mA电流，也就是2.5W，3.0的接口标准最大是1A电流，也就是5W。所以你要考虑你希望插在树莓派的USB HUB上插接的设备的功率。如果你需要高功率的设备，可以采购带外置电源的USB HUB，这样的话功率上限看USB HUB的电源功率。在这个功率下都不会拉低5V电压，也就不影响树莓派启动。

实际上你两边都应该考虑，考虑一下树莓派的供电电源功率，和树莓派外接的USB HUB上设备的功率。谈到树莓派不能启动的话，我个人感觉还是前面树莓派的供电电源对启动的影响更大些。

posted by wap, platform: MAC OS X
选择USB HUB的时候，注意一下接口版本，尽量选择USB 3.0以上的。不过你要是老版本3B+以前的树莓派，是没有USB 3.0接口的，那么你把USB 3.0的USB HUB插到树莓派USB 2.0的接口上也没什么意义。如果是树莓派专用的，可以选择便宜的USB 2.0 HUB。

其实我觉得没什么好推荐的，你只要注意一下上面说的原则就能自己选了： 1. 要支持外接供电  2.USB协议不小于树莓派接口

引用:

原帖由 zxsoft 于 2021-5-22 16:48 发表
posted by wap, platform: MAC OS X
没看懂你说的是把树莓派的电源插在USB HUB上，还是把USB HUB插在树莓派上。如果是前者的话，你先考虑一下功率和供电方式。你要同时使用几个树莓派。一个树莓派4B的电源是5V3A,所以 ...

树莓派4所有usb都是接到供电电路
usbhub 接上以后 如果usbhub没有电源隔离 它回又电流流回树莓派usb口
这样就干扰树莓派的供电电路 树莓派就启动不起来
所以需要一个 带电源隔离的 usbhub 让它不反向充电
具体看这个讨论
https://www.raspberrypi.org/forums/viewtopic.php?t=244900

这是个野生解决方法 但是我动手能力不行
I currently have a Raspberry Pi 4 8GB with 2 USB 3 4 port hubs connected to 4 Hard Drives (18Tb total) as well as USB 3 SSD enclosure for USB booting. I am using it as an enhanced RAID system.

The problem is all these cheap 4 port USB 3 hubs that you find on both eBay and Amazon are very poorly designed. The external 5V is connected to both Upstream and Downstream VBUS which causes confusion in the Raspberry Pi USB controller and the back powering problems. It has been suggested to cut the red cable (VBUS Upstream) between the Pi and the USB hub, however this is only half the job. I have found that just cutting the red cable with my connected Hard Drives the Pi would randomly not recognised the attached Drives or not see the Drives after a reboot. I have also found that the Hard Drives would not reset or enter standby after a reboot leaving the Drives in a active state.

The only way was to send a software reset to the USB hub or disconnect and reconnect the Drive for the Pi to see the Drives which is a right pain.

:idea: The way round this problem is to disconnect the Pi Upstream VBUS Red Cable and connect it to the reset circuit of the USB Hub Controller chip. The USB Hubs I have been using have either a GL3510 or GL3520 Controller chip and both the external 5V rail and the Upstream VBUS are both connected to the reset circuit, so there is no way of resetting the Controller chip by lowering the Upstream VBUS. You need to lift one end of R1 disconnecting that end from the external 5V rail and solder the Pi Upstream VBUS cable to the other end of R1.

posted by wap, platform: Android
惠普的hstnn-ix06 3005pr

5V3A * 5