I’ve been shopping for a micro USB cable for a while now and had no luck – I have an Arduino board that seems to work with exactly one cable (Blackberry-branded) and nothing else. http://www.eevblog.com/forum/reviews/quick-and-dirty-micro-usb-test-jig-and-results/ suggests there can be considerable range in the voltage you can expect to get out of them, and there seems to be no way of telling what you’re getting just from looking at them.
I had some ~$3 ones that I got from a non-Amazon source (can’t recall where) that held up for a year of heavy use. I’m going to give these a try.
$9 for a USB cable is pretty crazy too. With reasonable care, the cheap retractable ones have lasted me indefinitely. The key is to pull from both ends to unspool or retract. Another option is a very short (<1’) non-retractable cable.
That is my usual option for my “go bag”. I tend to use the retractable ones in cars, so they tend to take a beating.
I have a couple 3-4 inch micro usb cables I tend to keep in motorcycle jacket pockets, I like retractable cables for a bit more room to spread stuff out when I can get it and if I am carrying a bag, I like them. All too often however the cheap ones do this to me:
I got a retractable ipod-to-usb cable out of a clearance bin at my grocery that worked great for the better part of a year until a car ran it over. I liked it because you could spool it out to any length and then the center of the spool was a button that retracted it. I assumed they were all like that.
I replaced it with like the cheapest one on Amazon. it was free shipping but it took like a month to arrive; also you have to unspool it all the way and then give it an extra tug to retract it–both points are mildly annoying but acceptable for $1.63. I use it every day at work for the last 2.5 months, no problems. I won’t run an ad for them but hit me up if you want the info.
I just attach a velcro One Wrap strap to the cable, and adjust the cable to whatever length I need. I’ve used retractables in the past, and it’s a toss-up as to whether or not the spring will break before the flimsy cable will. However, all the $1.99 USB cords I’ve picked up in the cut-out bins at Fry’s are still working great.
These are handy for more than just USB. Cut off the connectors, add other ones, voila - headset cable. (You can also mod the headset with a USB connector so you can exchange cables easily, shorter or longer as you wish. Different ends not so needed now when all I use has the 3.5mm jack.) Or charger cable (if current low enough). Or whatever you please cable, up to few 100s mA and 4 conductors.
I did this with the cable that goes between the wall socket and the laptop power supply. Saves a lot of space and weight as the mains cable is too thick and heavy.
Out of curiosity, is your one-magic-cable situation when running from a computer’s USB port, a USB charger wall wart, both?
I ask because, in addition to just plain lousy build quality and skimping on materials, there is all manner of goofy nonsense in the world of USB-for-power (signal voltages on D+ and/or D-, resistances within specific ranges between one or more pins, combinations of the above, possibly witchcraft) caused by a mixture of proprietary vendor idiocy and the ponderous vagaries of the USB-IF’s standards process (USB, then USB OTG, then USB ‘charging downstream ports’ which look like normal USB ports but have different power negotiation behaviors entirely, the addition, then removal, of resistor-based detection in “USB Battery Charging Specification” (added in 1.1, removed in 1.2).
An arduino board should be smart enough to handle good, honest, power unit load negotiation, if the device it is connected to is a full USB host rather than a dumb charger; but all bets are off if that isn’t the case.
If it is being connected to a computer, it might be interesting to see how it appears, and what it negotiates for, in terms of power. More than a few devices tell outrageous lies, some are even broken enough that they only work if the host politely ignores some parts of their request.
A cable is a cable. These resistors are handled on the side of the power supply, the D+/D- wires of the cable just carry the voltages to the device. If the wires themselves are thick enough for a given current to not cause too significant voltage drop.
The arduino board is “dumb” in this regard, as the Raspi is; no negotiation, just blindly taking current from the power/ground pair.
[quote=“fuzzyfungus, post:10, topic:44831”]Out of curiosity, is your one-magic-cable situation when running from a computer’s USB port, a USB charger wall wart, both?[/quote]That one cable works perfectly regardless of whether it is plugged into a computer’s USB port or a powered hub. (I have no dedicated USB charger on hand for testing.) I’ve tried four different cables now and none of them work in situations where the Blackberry cable works; at least two of them can work as data transfer cables for my Blackberry device.
The Arduino board itself is indeed dumb and is completely unrecognized by the computer.
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