blocked USB charging

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marcowire
 
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blocked USB charging

Post by marcowire »

Hello Forum,

I have recently read about blocked USB charging: some manufacturers like Apple and Sony have blocking USB charging. This is a method of ensuring that you can only charge the device using a computer or a company charger.A
The USB cable has 4 pins, two for power and two for data. When connected to a computer, all 4 are in use. When connected to a charger, only the power pins are being used. These companies make devices having electronics that disable charging if there is no data activity.

What should I do with the data cable on the USB wire to allow even Apple devices to be charged?

I believe that Apple does it 'their way' with a non-USB compliant, proprietary, patented and licensed solution. If the Apple device doesn't detect an "Apple" charger it should treat it as a standard USB port, ie can supply up to 500mA. So charging may take longer..

Should I plug a non-Apple device into an Apple charger? People tell me NOT to do so.

On the other hand, we can plug an Apple device into a non-Apple charger and this may run at lower capability than if we had used an Apple charger.

thanks,
marcowire

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adafruit_support_bill
 
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Re: blocked USB charging

Post by adafruit_support_bill »

You may find that this answers a good many of those questions: http://www.ladyada.net/make/mintyboost/icharge.html

Roth2755
 
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Re: blocked USB charging

Post by Roth2755 »

I use an HTC charger with a 3rd party iFrogs charging cable. No difference to me :)

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marcowire
 
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Re: blocked USB charging

Post by marcowire »

thanks for the help.

Adafruit support, in the tutorial on the Minty Boost, the two data pins on the USB cable are connected together directly to each other (short circuited), correct?
I read that some people use resistors instead of a short circuit. Here from the internet:

"...On many of today's smart phones and MP3 players the device won't start charging or use the power from USB unless it is receiving a small voltage
on the Data + and Data - lines. These devices , such as all Apple iPods and Phones, are looking for 2V on the D+ and about 2.7V on the D- lines.
So voltage dividers are needed to accommodate this. As you will see in the schematic R1, R2, and R3 are feeding the D- line. I found the best
resistor values for this where 22K ohms on R1 and a total of 26K between R2 and R3. Two resistors are needed here because 26K Ohm resistors are
hard to come by. Then we have a 22k Ohm and 15K Ohm feeding D+. Other resistor values can be used as long as the end result is close to 2V on
D+ and 2.7V on D-. I've used this arrangement in past projects and know it works so i'm sticking with it for now. I've tried resistor values under 10K ohms and they don't work. So if you decide to go with a different voltage divider setup make sure the values are greater then 10K ohms...."


Do you know why? If we instead short circuit the D lines they end up with the same voltage.

thanks
marcowire

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adafruit_support_bill
 
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Re: blocked USB charging

Post by adafruit_support_bill »

Adafruit support, in the tutorial on the Minty Boost, the two data pins on the USB cable are connected together directly to each other (short circuited), correct?
No. In the link posted above you will see the resistor network used in the MintyBoost.

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