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An USB plug that goes both ways

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Re: An USB plug that goes both ways

#101

Post by Natsu »

AlexandrB wrote: post #62
marshray wrote: post #38

Earlier quoted context omitted.

I'd expect current limiting to be a feature of even the cheapest USB interface ICs. It's really easy to test and potentially a short-circuit/fire hazard. Not the kind of thing any testing lab would be likely to overlook.

Funny story. I assumed this as well - but while working on a school project I fried a very nice motherboard when our project got a short from a wire that had come loose. Lesson learned - use a separate power supply and keep the USB only for signalling.

Also in this vein: try explaining to your bosses why spending money for an AC adapter for a USB I/O device in a business-critical piece of hardware that does not tolerate lost signals well is a justifiable expense when it is perfectly capable of getting power from a USB cable into a computer that is already powering entirely too many things.

I actually bought it myself and smuggled in the upgrade just because the headaches it would cause me, personally, weren't worth it.

Re: An USB plug that goes both ways

#102

Post by artsrc »

sliverstorm wrote: post #26
colanderman wrote: post #9

I've always wondered, why aren't USB connectors designed to be able to be inserted either way? Does having 4 contacts vs 8 really save all that much money?

My other wish has always been 'uni-sex' USB plugs, but I don't know if you can easily have both 'uni-sex' and invertible together.

Raskin described a plug like that in his human factors book that I read. Probably:

http://www.amazon.com/Humane-Interface-Directions-Designing-...

Re: An USB plug that goes both ways

#103

Post by thushan »

I never understood why plugs like that needed to go a certain way. On a technical standpoint, yes, I get that the leads need to be oriented in such a way, but why design it so people have to think about it? Apple's mag safe connector is a perfect example of how plugs should work - it does not require anyone to think about what the correct orientation is.

Same with magnetic stripe readers for credit cards and transit passes. At this point, that reading technology is so ridiculously cheap that there should be no reason why we can't put in four different sensors so that it doesn't matter what orientation you swipe a card with.

Re: An USB plug that goes both ways

#105

Post by eru »

JacobAldridge wrote: post #100
eru wrote: post #94

Earlier quoted context omitted.

Put your hands in front of you, palms facing outwards. Your left hand is where thumb and index finger form an L. (Or if he's into cars, explain it via `where the cars drive'.)

Put your hands in front of you, palms facing inwards . Where the thumb and index finger form an L, that's your right hand. And of course, cars where I grew up (Australia) drove on the opposite side of the road to the cars on tv (mostly US shows and movies). I think these are both great ways to help teach kids left and right; I just like to point out the flaws since neither way helped me (and I still have to think abo…

Didn't I imply that cars drive on the right side i.e. the left side of the road?

Re: An USB plug that goes both ways

#106

Post by eru »

tedunangst wrote: post #84
eru wrote: post #58

Earlier quoted context omitted.

That's what coins are good for.

The chances are only 50/50 before you decide. After making your choice, the state collapses to 90% wrong.

That's why you don't decide. It's called a mixed strategy. (http://en.wikipedia.org/wiki/Strategy_(game_theory)#Mixed_st...)

Re: An USB plug that goes both ways

#107

Post by pbhjpbhj »

eru wrote: post #94
bad_user wrote: post #93

Earlier quoted context omitted.

How cute :) Btw, to help him learn you could attach a bracelet to his left or his right hand. Give him a landmark that he can recognize.

Put your hands in front of you, palms facing outwards. Your left hand is where thumb and index finger form an L. (Or if he's into cars, explain it via `where the cars drive'.)

>Your left hand is where thumb and index finger form an L.

This would work except that young kids get letters wrong too and a common mistake is to mirror L.

Re: An USB plug that goes both ways

#108

Post by JBiserkov »

Reminds me of Microsoft's Instaload design for batteries: "The two batteries can be inserted in any of the four possible orientations as shown above and the device works."

Source: http://www.microsoft.com/hardware/mouseandkeyboard/licensing...

HN Discussion http://news.ycombinator.com/item?id=1480059

Re: An USB plug that goes both ways

#109

Post by JoeAltmaier »

jws wrote: post #30
marshray wrote: post #25

Earlier quoted context omitted.

What? You didn't notice the mark clearly embossed in black plastic on the black plastic background while holding it in the illuminated space between the back of your computer and the wall? Or maybe yours doesn't have a mark at all like the mouse I'm using now. Or maybe it has one mark on one side and a slightly different mark on the other. Who came up with this stupid idea anyway of making a plug that looks and feels…

Come on, it's right there in section 6.5.1 of the specification which you'd know if you searched the web, downloaded 11MB of data, unzipped it and sorted through it for the "Universal Serial Bus Specification Revision 2.0", then read all 622 pages of that. 6.5.1 USB Icon Location The USB Icon is embossed, in a recessed area, on the topside of the USB plug. This provides easy user recognition and facilitates alignment…

So, how do you identify the hole orientation? Does it have a mark too? What possible use is identifying the plug orientation without that?

USB plugs are a giant step backward.

Re: An USB plug that goes both ways

#110

Post by JoeAltmaier »

nitrogen wrote: post #14
51Cards wrote: post #7

Very cool but here's my initial concern. When the set of four contacts are flipped over on top of themselves their order will be reversed and that leads to a potential for a short. The center two pins being data aren't as big of a deal but the outside pins, namely the +5 and ground would be opposite each other and quite close. Since the surface they are mounted on slides, it could potentially also wiggle up and down.…

USB ports are probably current limited, so it's unlikely that a momentary short will burn them out. However, dissipating 2.5-4W (depending on the port's power capability) through a few small components will cause them to heat up over time, which may burn out the port.

Plugged a device backward into my Dell monitor; got the "current limit" dialog popup; port was fried.
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