I have a raspberry pi, powered by one 1 Amp power supply (named A) , and a 7 port USB hub powered by a second 1 Amp power supply (named B). The 7 port USB hub is used for a 1 TByte USB disk and a USB wireless adapter. The raspberry pi is only connected to 10/100 ethernet, as I operate the raspberry pi via X and ssh only.
I note that if I do not power up the A power supply, the then USB hub powers the raspberry pi. I have not undertaken any load tests with using just the USB hub to power the raspberry pi.
Question: - is it recommended to use one or two power supplies? And if two power supplies are used, is there any risk to the raspberry pi due to possible voltage differences between the two power supplies? Or is there sufficient isolation within the USB connection to minimise the risks?
Thanks in advance
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Re: Power Supplies
Hi,
What you could do is to cut red wire of the cable linking RasPi and the USB hub.
Best wishes, Ivan Zilic.
One only for supplying one box.rif6894 wrote:is it recommended to use one or two power supplies?
There is no isolation at all.rif6894 wrote:Or is there sufficient isolation within the USB connection to minimise the risks?
What you could do is to cut red wire of the cable linking RasPi and the USB hub.
Best wishes, Ivan Zilic.
Running out of GPIO pins and/or need to read analog values?
Solution: http://www.flyfish-tech.com/FF32
Solution: http://www.flyfish-tech.com/FF32
Re: Power Supplies
If your Pi suffers from freezing, kernel panics, weird boot up messages or random reboots then you've probably got a power supply issue.
Usually checking TP1/TP2 for out of spec voltage is a good indication but doesn't always follow true - http://elinux.org/R-Pi_Troubleshooting# ... r_problems
As for the USB hub it's important that it doesn't backfeed power into the Pi and is powering it without using the normal route.
There is a small possibility that input voltage maybe too high and could burn out the TVS protection diode, if your hub is backfeeding then open it up and cut the red wire inside.
Richard S.
Usually checking TP1/TP2 for out of spec voltage is a good indication but doesn't always follow true - http://elinux.org/R-Pi_Troubleshooting# ... r_problems
As for the USB hub it's important that it doesn't backfeed power into the Pi and is powering it without using the normal route.
There is a small possibility that input voltage maybe too high and could burn out the TVS protection diode, if your hub is backfeeding then open it up and cut the red wire inside.
Richard S.