A few weeks ago I aquired the Pi2, my second Pi and I have to say I am generally very happy with its performance.
There are a few questions regarding its setup and use...
One problem I have is to find a suitable powered hub. I bought one of those 7 port hubs (silver, upright with stand- lots of those on various internet sites), as it promised 3 amp (!!) current supply. I intend to connect everything USB to the hub and then to the Pi2, like I did with my first Pi.
I have a problem though... If I power the hub first and then the Pi, I get lots of errors (I/O errors, exec format errors interrupts errors and so on, and the Pi is lost... If I pull the Pi2 power cable the Pi2 continues to be powered apparently through the USB HUB!!!!!
If I power the Pi2 first and then power the hub or connect it after the Pi2 boot everything is OK!!!!
Is there a conflict with the power supply here??? Should I modify somehow the cable connecting the hub to the Pi2, disconnect the red power wire and leave only the signal wires?
I have to say here that if I use the powered hub supplied by Maplin -that triangular one- (I bought my previous Pi as a complete kit from Maplin) everything is OK.
There is a problem here.... You cannot say the USB hub is suitable until you use it ie open its pack.. if unsuitable it cannot be retuned! Same goes for some power supplies advertised as suitable for the Pi but useless in practice – giving the same sort of errors at boot!!!
Another problem associated with the hub is that if the Pi is left for some time on without any activity, USB devices connected to the hub do not respond, I have to disconnect the hub from the Pi port, reconnect and then they become active again.
I never had this kind of problem with the Pi1!!
Another question regarding the I/O pins.... Can I use all the GPIO pins as digital I/O?
And a final question.... As soon as the graphic interface starts I get a dialog box with the following error:
GDBus.Error:org.freedesktop.PolicyKit1.Error.Failed: Cannot determine user of subject
What does it mean and how can I get rid of this?