1 BB xM 2 PSUs

The HDD that I bought for my Beagleboard xM has a Y USB lead to gain sufficient power. It had problems getting that from the BB so I plugged the second lead into a USB mains adapter. Pulling the BB’s power plug I was surprised to find the BB remaining live, taking its supply from the 2nd adapter. I didn’t realise it could be powered through the A receptacles.

Before adding the 2nd PSU I gained the best response plugging the drive into 2 ports on my monitor’s built in hub. Even then booting up gave a waiting for drive message, continuing to boot after a significant pause. With the the extra supply it all ‘just works’.

Is this OK or likely to cause problems?

I would also be interested to know the answer to this, having had a similar experience when using the Beagleboard with a powered USB hub. I use a Freecom Classic HDD which, until after the Wakefield Show this year worked happily with just one USB socket (N.B. not a Freecom Classic II: I have one of those also and it’s always needed a Y USB lead).

Strangely when setting up at home again after the show, the older Freecom drive was no longer happy booting to Linux on the Beagleboard with only the one plug (it was fine in RISC OS, which is on the first partition on the drive). We tried using a little powered USB hub, and it was then fine, apart from two things. One was the business of the Beagleboard getting power this way, like Frederick’s, and I was slightly uneasy about that. The second problem was that somehow our ADSL Switch/Router got upset whenever the Beagleboard was operated this way, and kept losing its internet connection! I really don’t understand this: if an electronics expert could suggest an explanation that would be wonderful. Could some sort of over-voltage be getting through from the USB hub, to the Beagleboard and via the Ethernet lead to the router?

In the meantime we have had to resort to using the HDD via a Y cable, but with keyboard and mouse plugged in too we end up with no USB sockets free, which is a nuisance. Adding the powered hub causes the problem with ADSL.

If anyone can recommend another model of drive (maybe solid state) which really can run off the power from a single USB socket, that would be of interest to me. I know from experience that many PCs can provide more power via a single socket, so support a wider range of USB drives. The Iyonix, the Beagleboard, and the NSLU2 all conform to the USB spec more closely, I suspect, and don’t have much spare power to dole out. So please don’t recommend unless you’ve tried with a Beagleboard.

A few days ago we had another couple of ideas. Using the USB hub without power it is possible to plug the keyboard and mouse into it instead and free up one socket that way, but the devices are not always activated after booting, so it’s unreliable.

Finally, we discovered that the USB’s power supply actually fitted a little power socket on the HDD itself, so we could try powering the drive direct. But the drive made funny clicking noises when plugged in this way, so I didn’t like to leave it like that.

I think we either need a better USB hub, that doesn’t interfere with the Beagleboard’s power and the router, a better router which doesn’t get upset, or a USB hard drive which can run off one socket and no other power. I’d be glad of any recommendations!

Hi,
Do you have the correct PSU for the HD ?
I take it from what you said above you tried it with the PSU belonging to the USB hub ?
If that’s the case, it may not be high enough voltage or current capability, or even both.

If you can use the original PSUs for both the USB hub & the HD, that’s the best solution.
I know that’s using 2 extra 13A sockets, but reliability is more important surely ?

It should be possible to provide one PSU that will power both HD & USB hub, but that requires some ‘hands-on’, which unless you’re in Aberdeen, I can’t provide.

HTH

Hi Dave,

Assuming you were replying to me (not sure) then I can clarify that the HDD does not have its own power supply. It just has a little socket for power, but the manufacturer expected the single USB plug to be enough and did not supply a power supply. It was the power supply from the powered hub we tried.

So originally we had the drive plugged in with a single USB plug direct into the Beagleboard: everything was fine, and we had a free socket, but it stopped finding the drive when booting to Linux for no apparent reason.

We’re now using it with a Y cable, occupying the only previously spare USB socket, and RISC OS and Linux are both fine.

We’ve tried with the drive plugged in (via Y cable) to a small powered USB hub, but (a) the Beagleboard manages to get power in from the hub too, which worried me as it worries Frederick, and (b) the router loses its ADSL connection frequently in this configuration (why?).

We’ve tried the keyboard and mouse in the hub (unpowered) and the drive via the Y cable direct into the board. This often works, but sometimes the keyboard/mouse are not picked up, so it’s not ideal.

Finally, we noticed the USB hub power supply fitted the hard drive’s power socket. It was my brother-in-law (an electronic engineer) who noticed this and plugged it in, trying it unconnected to anything at the time. The drive appeared to power up, but made clicking noises so I hastily unplugged it as I liked that even less. But it might be OK like that: who knows?

The voltage and current capability must be sufficient for the drive because it works when the drive is connected via Y cable to the hub. It’s just that when we have the powered hub connected to the Beagleboard the router keeps losing its ADSL connection!

Sorry I seem to have hijacked this thread: I’d also like to know the answer to the original question.

Plus any recommendations for drives that are happy with just one socket to power them: I’d be prepared to buy a new drive if it was going to solve the problem.

Hi Matthew,
Yes, I was replying to you :) Sorry I didn’t make that clear.
Having said that the advice was generic enough to apply to Fred.
The Y lead is ONLY intended to connect to 2 USB ports on 1 powered device, usually a laptop, since these usually restrict the current available through each port.

Most modern 2.5" USB drives should only need the power from one port.
Best solution, I would ask your brother-in-law to check the specs for the HD, and pick up a PSU from Maplins or similar.

HTH