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Author Topic: How to protect the computer itself  (Read 1083 times)
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Bristol, UK
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Hi,

So i'm tinkering away, i've got a 12v seperate line going in, and the arduino powered from the usb...

everything is going fine, tweaking away the way we like to by doing it live and seeing all those leds light up one by one, and click i tap the -ve line for one side of the board straight into the adjoining 12v +ve line by accident, and pop...

well, kinda pop, the arduino reset, and the computer instantly shut down.

a quick click on the power button and all is well, the computer powers on, and the arduino is fine.

now, the specs say that the arduino is pretty hardy, and has internal fuses etc to stop problems, and tbh, i can buy another one for £25... not i'm not issued about that.

but the computer is a week old and cost over a grand...

it just made me think that maybe i should protect my system more, but how to go about it?

is it as simple as a usb hub before the arduino, or a simple, usb to small breaker containing diodes, and then on to the arduino?

has anyone made one before? they must have!
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I took apart the usb cable or rather cut into the wire placed a diode in series with the positive or negative wire to allow current to flow in to arduino not out...
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Bristol, UK
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simple, i like it!

is it a common problem?
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the land of sun+snow
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Your accident has been common since man first drove electron into wire. That's
why fuses were invented in the first place. Early cavemen were always touching
+ wire to - wire to see the big sparks. Electricity is fun.

That being said, ALL of the I/O pins in the typical Arduino board have no overvoltage
or short-circuit protection whatsoever. What works well is using small series-Rs
in "all" I/O lines, of value 220-330 ohms.

Also, I believe if you use a separate supply to power the Arduino bd, rather than
the USB, then overloading the bd should have less disasterous effects on the
PC USB port [but I'm not 100% certain of this].
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I see a project in your future...

http://www.analog.com/static/imported-files/data_sheets/ADuM4160.pdf

Maybe you can sample the part.  Or find someone who has already implemented it into a product.   Hmm, looks like someone has:

http://www.ebay.com/itm/USB-protection-ADUM4160-Evaluation-Board-USB-Isolator-/230842787049

Important caveats:

Quote
NOTE:

Since the chip supports isolation rate of Low Speed and USB Full Speed, can not be used as a USB2.0 high-speed, so please pay attention to use the requirements of buyers.

Equipment has been tested:

U disk, digital cameras and other high-capacity storage devices.
STM32, ARM debug using J-LINK.
AVR debugging USBasp.
PIC debugging using ICD2
Infineon debugging of miniwiggler.
Ti DSP debugging using XDS100 and so on.
« Last Edit: September 11, 2012, 12:34:47 am by JoeN » Logged

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Good points mentioned to secure a PC and one thing more, be careful about plugging USB drives and memory card readers to your computer.
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The Arduino does not push that much data through the serial port. I think I should order one of these USB isolators. Today I always use an active USB hub in between. So far I fried one hub.
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Check out my experiments http://blog.blinkenlight.net

Tucson, AZ
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I just ordered a couple samples of the ADuM4160 from ADI.  Will see about making up a couple of them.
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I just ordered a couple samples of the ADuM4160 from ADI.  Will see about making up a couple of them.

OH NOES.  Soon the sample nazis will be all over your posterior. smiley

I am going to have to remember to order one of those after my month cooling off period which started about 10 days ago.  smiley-lol
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Some cheap externally powered (that is, using AC adapter) USB hubs will not interfere with Arduino, and it is easier to sacrifice a $10 hub to a boo-boo than a $1,000 computer.  Consider using it as a ghetto fuse.
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I just ordered a couple samples of the ADuM4160 from ADI.  Will see about making up a couple of them.

OH NOES.  Soon the sample nazis will be all over your posterior. smiley

I am going to have to remember to order one of those after my month cooling off period which started about 10 days ago.  smiley-lol

Bah!  Reps for TI, ADI, Microchip, Fairchild - they call ME and ask what I need.
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