Electricity Supply for BeagleBoard

So I need a regulated 5V DC power supply for my BB. What do folk recommend? I want something portable, preferably. This is another item I don’t see in the hardware compatibility list. Is this the sort of thing one gets from Maplin? Gosh, I think I am joining the geeks.

Try Maplin’s L45BL

¹ satfooldeals.co.uk (registered on the Channel Isles!)

This is another item I don’t see in the hardware compatibility list.

AIUI the Cortex-A8 hardware compatability list is for peripherals (which acutally could include monitors, I suppose). Have you had a look at the shopping list ?

The L45BL is the one I bought. But be warned, make sure you get the polarity of the DC plug the right way round :-) Just in case you are tempted to chop off the adapter and solder a 2.1mm plug directly on the end of the wire – the internals might not be what you expect. It is hard to explain, but just imagine a multicore cable where half of the cores are coated in clear varnish and the other half coated in a red varnish. Most odd.

If you’re considering cases (as recommended in the how to get started page) note that there’s a customs charge on items from the US. The acrylic case is not the only one, either. But this metal alternative doesn’t give access to the board buttons. However, you can always use ctrl-break to reset (or unplug if desperate). Finally, there’s Jeffrey’s Lego case for inspiration.

imagine a multicore cable where half of the cores are coated in clear varnish and the other half coated in a red varnish.

Aargh!

The L45BL is the one I bought. But be warned, make sure you get the polarity of the DC plug the right way round :-)

The thing is, I’m not sure the polarity is actually mentioned anywhere in the reference manual! (Or at least it wasn’t when I got my beagleboard). Luckily I guessed right on the first attempt – the inner part of the jack should be positive, and the outer part negative.

As long as the power supply you choose can supply around 2A at 5V (and has a connector of the right size and polarity) you shouldn’t run into any problems.

Did anyone check the lowest input voltage for safe operation of the BeagleBoard? (I am asking with LIPO cells in mind)

DC input – min 4.8V, max 5.2V

Be careful with the LIPO batteries. In an article about them in a recent RadCom magazine it stated they are very particular about how they are charged and have a propensity to burst into flames

The BeagleBoard must have the resistor removed according to the instruction manual if a battery is to be used. Under those circumstances, the charging current can be expected to be low, so I can’t imagine how there could be sufficient power to heat the cell significantly. It’s a different situation from trying to cyclically charge and discharge batteries; under those circumstances one is normally trying to charge them in as short a time as possible, which does provide enough power to heat them significantly.

There will be roughly 2 volts across whatever resistor charges the battery connected to the BB, so there won’t be a huge difference in the current flowing through it within the permitted tolerance of the 5 volt input.

Has anyone found a cheap source of the aforementioned batteries? The best I’ve found, including postage, is still over GBP10.

The BeagleBoard must have the resistor removed according to the instruction manual if a battery is to be used.

That text is talking about the RTC battery. If you tried powering the board through the RTC battery connections then you’d be in serious trouble :)

Also I’ll second what John says about LIPO batteries. Search on youtube if you want to see what happens when they’re mistreated!

OK, you want to run a BB from batteries? You’ll need a regulator of some sort: (a) there’sno such thing as a 5 volt battery; (b) the discharge curve of any battery covers a range of more than +/-4%, so you’d lose a fair proportion of its capacity.

Choose a battery of the power capacity you need, then choose a regulator with an output voltage of 5 V and an input range to suit the battery. The choice of the two is likely to be somewhat interactive.

Regarding battery-powered beagles, this thread on the beagle newsgroup may be of interest.

Jeffrey Lee said: “The thing is, I’m not sure the polarity is actually mentioned anywhere in the reference manual! (Or at least it wasn’t when I got my beagleboard). Luckily I guessed right on the first attempt – the inner part of the jack should be positive, and the outer part negative.” What I find confusing is how to determine which way round to insert the power tip into the power supply socket of the L45BL power supply unit to ensure that the centre is positive. I know that in the strings o) and (o the o represents the centre and ) or ( represents the outside, but the markings can be interpreted in two ways. I know I had it right when someone tested it with a meter, but I have since taken the power tip out and don’t have access to a voltage meter.

Just to document that I’ve had no problem powering an xM board from a powered hub via a 5V DC USB male to 3.5mm barrel connector power cable with a 2A adapter. The setup was a Digitus USB 2.0 4-Port Powered Hub connected via USB OTG. I was fetching a page with NetSurf and copying files between 2 USB flash drives, running at 1GHz. The devices were attached as follows:

• On-board USB host
  1. Ethernet adapter
  2. USB flash drive 0
  3. USB flash drive 1
• 4-port powered hub (2A PSU)
  1. Keyboard
  2. Mouse
  3. USB male to 3.5mm barrel connector power cable (to board)

I know that powering a board in this way isn’t recommended, but in this instance nothing untoward happened. I guess physically spinning hard drives require more current, and so probably wouldn’t work like this.