MiSTer FPGA Forum

All,
I am using an an external USB Hub that uses a 5V 3A AC adapter. I am also using a 5V 6A AC adapter to power my MisterFPGA.
I noticed that my Mister is still on even after when I unplugged my MisterFPGA power supply. I have a couple of questions.

1. Do I even need the power supply for my Mister if I use the power supply for the USB hub?
2. Is it safe to use both the power supply for my Mister and my external USB hub at the same time?
3. can I just use the 5V 3A AC Adapter for my USB hub to power both the MisterFPGA and USB hub?

TIA.

kubbie wrote: ↑Sun May 22, 2022 8:40 pm All,
I am using an an external USB Hub that uses a 5V 3A AC adapter. I am also using a 5V 6A AC adapter to power my MisterFPGA.
I noticed that my Mister is still on even after when I unplugged my MisterFPGA power supply. I have a couple of questions.

1. Do I even need the power supply for my Mister if I use the power supply for the USB hub?
2. Is it safe to use both the power supply for my Mister and my external USB hub at the same time?
3. can I just use the 5V 3A AC Adapter for my USB hub to power both the MisterFPGA and USB hub?

TIA.

I found out that a powered USB hub will back feed into the Mister FPGA USB hub keeping it on all the time, I honestly don't know how safe that is, or if it would cause problems, I do know it was keeping some of my wireless controller dongles active after the Mister FPGA was turned off, my fix was to use the same power supply to power everything, I used a three way power splitter like this one:

https://smile.amazon.com/dp/B01MG6T9XP

along with a power coupling adapter like this:

https://smile.amazon.com/dp/B081Z7H444

a USB Power Plug like this:

https://smile.amazon.com/dp/B07Q5PHHFK

and a USB power splitter like this:

https://smile.amazon.com/dp/B01EL7INUG

This is what that looks like put together:
There is an added short 90 Degree USB 3.0 Type A Male to Male cable in that image that you may not need, you can get that over here:

https://smile.amazon.com/dp/B08SLVYR67

One of the USB connectors goes to the Mister FPGA USB hub, the other end can go to the powered hub or external hard drive, BTW you can get USB to DC power plugs of different sizes if needed so you can power different things, the single DC 5.5 x 2.1mm socket goes to your power supply, the two DC 5.5 x 2.1mm plugs go to your Mister FPGA and Mister FPGA USB hub.

With this wired up to one power supply, everything is turned off at the same time, you have the option of using a better higher amperage power supply, any external hard drives will work better, and USB devices power down when the Mister FPGA is shut off.

This looks like a useful solution, I'd really like to know if it's "safe" for the MiSTer components from an electrical perspective. I'm not convinced that the USB hub is designed to be used in this fashion, it obviously _works_ but are there any associated risks versus powering the device the "normal" way. Are we able to find someone involved in the hardware design who might be able to comment?

Thanks very much for the detailed information. I'm also curious if it's a good or bad thing for the Mister.