MiSTer FPGA Forum

Hi all, very quick question. I have a generic 4-port USB hub connected to my DE10 Nano. I power the DE10 via a 5v 6A PSU. Everything has worked fine so far, but I have only ever used 2 of the USB ports. If I start using all four ports, do I need to power the USB hub separately or will it be fine drawing from the DE10?

I hope this hasn't been answered before - I have searched the forum extensively and couldn't find it being addressed.

Welcome!

I think a 6A PSU is overkill, and might even be dangerous if you don't have it plugged into a separate wall socket. I'm using a 4A PSU and I've thrown everything but the kitchen sink on it (including an external DAC/amp); all ports (7 + serial port with a SNAC @ 5V) except one are always occupied (nb: I've a blisSTer through which both the DE10 and I/O board are fed) and I've never experienced a voltage drop.

However, don't try to drive an HDD or any other mechanical device off the hub in parallel with any other peripheral. The MiSTer follows the old usb 2.0 standard and allows for only 500mA on each port.

tl;dr: Yeah, you're better off powering the hub on its own.

Thanks. I was planning on using a DC splitter cable. So there's no risk of the power to the USB hub feeding back into the DE10 via the OTG cable?

GaiusMarius wrote: ↑Wed Jul 28, 2021 10:13 am Thanks. I was planning on using a DC splitter cable. So there's no risk of the power to the USB hub feeding back into the DE10 via the OTG cable?

No, the only risk of a power feedback is only through an HDMI cable that's at the same time 'CEC aware' (as in when you got your MiSTer interconnected to a home theater or something). With normal use you're good, as long as you don't plug that 6A PSU on the same power line with your PC (or your A/C, or your vac, or your power tools) etc.

lamarax wrote: ↑Thu Jul 29, 2021 7:15 pm With normal use you're good, as long as you don't plug that 6A PSU on the same power line with your PC (or your A/C, or your vac, or your power tools) etc.

Why exactly?
Perhaps I'm mistaken but I always thought that 5V 6A equals 30W. That is less power than the average old-fashioned light bulb.

PQR wrote: ↑Sat Jul 31, 2021 12:45 pm

lamarax wrote: ↑Thu Jul 29, 2021 7:15 pm With normal use you're good, as long as you don't plug that 6A PSU on the same power line with your PC (or your A/C, or your vac, or your power tools) etc.

Why exactly?
Perhaps I'm mistaken but I always thought that 5V 6A equals 30W. That is less power than the average old-fashioned light bulb.

Not sure. 30w might be 6A at 5V but if you're on 240v mains it is only 130ma (plus some extra for losses) so I don't see an issue. Cabling in walls is specced above the current rating of the fuse box. So the issue is power strips where they can become a problem when people start sticking loads of high load items on them, fan heater with a kettle etc... And only in nations like America really where they have lower line voltage and plugs without fuses, that always seems like a recipe for fire

With you average strip powering your electronics there is no big problem outside of having a mess of cables.

Given that breakers blow at 15A for most outlets, any MiSTer setup even with the highest PSU size you can imagine is just a small drop compared to anything that might actually put you in trouble of blowing the breaker.

Blitzwing wrote: ↑Tue Aug 03, 2021 10:40 am

PQR wrote: ↑Sat Jul 31, 2021 12:45 pm

lamarax wrote: ↑Thu Jul 29, 2021 7:15 pm With normal use you're good, as long as you don't plug that 6A PSU on the same power line with your PC (or your A/C, or your vac, or your power tools) etc.

Why exactly?
Perhaps I'm mistaken but I always thought that 5V 6A equals 30W. That is less power than the average old-fashioned light bulb.

Not sure. 30w might be 6A at 5V but if you're on 240v mains it is only 130ma (plus some extra for losses) so I don't see an issue. Cabling in walls is specced above the current rating of the fuse box. So the issue is power strips where they can become a problem when people start sticking loads of high load items on them, fan heater with a kettle etc... And only in nations like America really where they have lower line voltage and plugs without fuses, that always seems like a recipe for fire

With you average strip powering your electronics there is no big problem outside of having a mess of cables.

Exactly, that is what I was thinking too. Thanks for confirming.