Fri Apr 25, 2014 12:44 am
Hi all
I've examined these USB hub issues a lot and read many articles/forums about it. Also tried various USB hubs with my Pi. Some were powered, some were not and some of them with/without a no back power function.
here are my suggestions;
First of all, we must have a good quality, at least a real 1A power adaptor for the Pi itself. Most of the hub problems comes in if you do not feed your pi with a good power source. I've experienced different stability and boot up problems when I use different (cheap and expensive ones, all 5v 1A) power adaptors for the pi, with exactly the same pi & hardware setup (same usb hub, same sd card, same os, same usb devices.). Just power adaptor changes and boom, system loses stability like usb devices connected to the hub not working.
With 1 X logitech wireless keyboard & mouse, 1 XTP link wifi adaptor, 1 X external HDDs, 1 X usb light and 1 X 32 gb Usb stick;
I've tried using pi with an original 5v/1A iphone adaptor and it works good.
I've also tried original samsung galaxy note 2 5c/2A and it also works great. So main problem here is not he HUB itself I guess, but the power adaptor/s.
Secondly, we have to use a powered hub for sure, especially if we are going to use many usb connections like wireless keyboard, mouse, wifi adaptor, HDDs etc.. That is also a must.
As it comes to back power issues; I've found out that the most important element in these backpower issues is not the hub itself, but the power source of the pi as well as the power source of the Hub. I mean power adaptors. If you have a good quality power source (adaptor) for your pi with at least 1A (I mean real output, stable and good quality 1A) or more, your pi will work very very stable rather it's connected to a powered hub with a back power functionality or no backpower. Backpower won't effect your pi's power stability in most cases. I've used 4 different, cheap powered hubs, all made in china and had no problems with any of them on long terms. All still working smoothly.
After some research, I've found out that the best chip around manifactured and used in powered USB Hubs is so cheap that, most of the manufacturers use the same one for their powered USB hub products, even if it's a cheap china made model or a quality one like a Logitech or Microsoft. Both use the same chip in general. What makes the difference is the power adaptor. If you buy a cheap powered USB hub, it's power adaptor coming out of the box may not sustain the power that the hub needs. So, I also recommend to replace the power adaptor of the cheap powered hubs with quality ones.
To summerize what I can suggest is;
1. Use/buy quality adaptors, both for the Pi and the HUB.
2. If you have a digital meter, check their real rates/outputs. It's easy.
3. Try to keep it at least 1A when you are buying a (good) adaptor for the Pi.
4. You may go even over 2A as you add more usb devices to your Pi/Hub. Remember this if system gets unstable, USB devices gets suddenly disconnected or they become unresponsive randomly.
5. When buying a quality adaptor for the powered USB Hub, check the rates of the original one. Buy with the exact same voltage. But you will definitly want to buy one with a higher amper value, like 2A. Sooner or later, you'll need higher Ampers as you start to connect more and more usb devices.
6. If your powered USB hub has backpower function, try to power on both the Pi and Hub at the same exact time. This will highly reduce USB device errors. (like bad disk, mount/umount and safely remove errors) You may want to use a simple plug with a switch for that. Just turn the swith on and Pi & The Hub will power on at the same time. This will also keep fragile micro usb power port and usb ports of the pi safe.
7. If you are using 3.5' HDDs, do not try to power it from The Pi, nor from powered USB hub. Power it directy from another source. They consume very high power which will probably effect the stability and power balance of the system.
8. Rarely, backpower may create problems. But in most cases, the problem is the power adaptors. Buy a good one/s!