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BobbyPaulk(at)comcast.net
Guest

Posted: Thu Dec 29, 2016 5:12 am Post subject: USB

Guys 



I have noticed some USB ports will charge a Samsung or other device and not an I-phone or other I-thingy.



Is one available that wold do both or do I have a faulty port.



Bobby



analog guy in a digital world

nuckolls.bob(at)aeroelect
Guest

Posted: Thu Dec 29, 2016 7:49 am Post subject: USB

At 07:11 AM 12/29/2016, you wrote:

 Guys 

 I have noticed some USB ports will charge a Samsung or other device and not an I-phone or other I-thingy.

 Is one available that wold do both or do I have a faulty port.



 

    There are USB ports . . . and then their are USB ports.

    The legacy USB port was conceived as a bi-directional,

    serial data port for SMALL accessories like thumb drives,

    mice, keyboards, etc. Power supplied from this port was

    offered at rather small rates . . . 100 to 500 milliamperes.



    Many computers were fitted with positive temperature

    coefficient current limiters (poly-fuses) to protect the

    computer from damage should the +5 volt USB power line

    become overloaded.



    Years later, new kids on the block (phones, tablets, etc.)

    found it useful to exploit that handy source of regulated

    voltage to charge internal batteries while in communication

    with a host computer . . . or even as a low-power charging

    source where leaving one's device on-charge overnight was

    no big deal.



    Simultaneously, demands on performance for USB ports

    evolved with ever higher transfer speeds. Accessories

    that exploited USB ports also evolved . . . there are

    electro-mechanical hard drives that will function

    solely on a 5 volt power supply while demanding less

    than 500mA.



    Then came the big kids. Tablets and larger smart

    phones that communicate with other devices

    via, you guessed it, USB ports. At he same time,

    their energy needs for both function and battery

    charging grew to 3 or 4 times that which the

    computer-based USB port could provide.



    This gave rise to proprietary chargers capable of

    1 amp or more of 5v power. Problem was that if you

    configured your mini-super-pc to demand say 2A of

    battery recharge current, how do you keep it from

    overwhelming the 5v source on a legacy USB computer

    port?



    Instead of 'smart source ports' on computers, high-demand

    appliances evolved into 'smart-loads'. When the USB

    port was being used for only functional and/or battery

    charging power, then idle data lines could be used

    to tell the smart load how much power was available.



    Over the years, proprietary chargers lead the way

    to mostly accepted standards for tying idle data

    lines to each other or perhaps tying them to +5

    or ground with certain size resistors.



    This little hat-dance in the source connector

    informed smart-loads as to how much

    energy was available. I have at least one device

    that annunciates "slow charging" behavior when

    plugged into a computer . . . with no such

    annunciation when being powered with a high-current

    source.



    The SHORT story in this thread tells us that it

    is insufficient to simply craft robustly powered,

    panel-mounted USB receptacles with an expectation

    of maximizing exploitation of that source.



    I've not taken time to study USB charging philosophies

    in detail but know that there is a lot of data on

    the techniques available on the 'net. It's a sure

    bet that any DIY power sources for your favorite 

    cockpit companion may need a bit more information

    as to who much power is available. lacking such

    information will most certainly force the appliance

    into a 'slow charge' mode.



 

   Bob . . .    	 		 			 				 			 		 		 			

 				This email has been checked for viruses by Avast antivirus software. 				

www.avast.com

rampil

Joined: 04 May 2007
Posts: 870

Posted: Fri Dec 30, 2016 3:43 am Post subject: Re: USB

At least in the Apple world, the resistor network which informs the

device to be charged of the charger's capability and compatibility is

actually in the charging cord. If I remember the tech specs, the amperage

capacity is detected by voltage drop across the resistor.

Bottom Line:   If you want to charge an iPad or iPhone use a "genuine" Lightning cord.

_________________
Ira N224XS

BobbyPaulk(at)comcast.net
Guest

Posted: Fri Dec 30, 2016 4:36 am Post subject: USB

Thank you Bob and Eric for the explanations.



Great information for an old geezer. 



bobby

ceengland7(at)gmail.com
Guest

Posted: Fri Dec 30, 2016 5:53 am Post subject: USB

On Fri, Dec 30, 2016 at 5:43 AM, rampil <ira.rampil(at)gmail.com (ira.rampil(at)gmail.com)> wrote:

 	  Quote: 	
		  --> AeroElectric-List message posted by: "rampil" <ira.rampil(at)gmail.com (ira.rampil(at)gmail.com)>

 

 At least in the Apple world, the resistor network which informs the

 device to be charged of the charger's capability and compatibility is

 actually in the charging cord. If I remember the tech specs, the amperage

 capacity is detected by voltage drop across the resistor.

 Bottom Line:   If you want to charge an iPad or iPhone use a "genuine" Lightning cord.

 

 --------

 Ira N224XS

 



	
Or, simply stay away from that world....

jim(at)PoogieBearRanch.co
Guest

Posted: Fri Dec 30, 2016 6:43 am Post subject: USB

Earlier today, someone said that to charge an Apple device, you had to

use an Apple lightning coord.  That is partially true, in that a cord

sourced from Apple WILL work, but there are alternatives - and some are

much better than Apple's own lightning cords.  The "trick" is to

purchase only "Apple MFi Certified" lightning cords. 



My personal choice for the supplier is Anker - sold through Amazon. They

make MFi certified cords (complete with the unique authorization chip

like Apple uses) that work beautifully with all Apple devices, are

available in multiple lengths (1,3, 6, and 10 feet) and in several

colors (red, white, blue, gold, space gray), all for very reasonable

prices (much lower than Apple's own flimsy cables).  I've never seen the

"unapproved charging cable" notice when using an Anker cable.

My favorite is the double-braided nylon-sheathed PowerLine+ cables. I

use a "space gray" 6-ft version to charge my iPad Mini in flight, so

that the cable 'disappears' when laid across my gray glareshield cover.

I like the longer cable for this purpose, because my charging port

(cigar lighter with an Anker 2-port USB adapter) is on the right side,

but mounting the iPad there would interfere with entry/egress, so I have

to mount it on the opposite side of the airplane.

These double-braided nylon sheathed cables are very durable, far more

flexible than standard cables, and they don't seem to tangle as much.

They even come with a magnet-closed "cover" to keep the cord neat when

not in use.  I know it probably seems crazy to be this enthusiastic

about such a trivial product, but after spending $20 on "genuine Apple"

lightning cables, only to have the ends rip off, or the insulation

covers develop holes that lead to kinks and shorts, finding a

much-less-expensive alternative that not only works well, but is

virtually indestructible just makes my day.  I've given many of these

cables as "stocking stuffer" gifts to my kids and family, and everyone

just loves them. 

For those of you who use non-Apple devices, Anker also makes standard

Micro USB and USB-C cables (with all the same options) for those devices

(most Android phones and tablets). They also make a pretty nice 2-port

USB adapter for you cigar lighter that will charge two 2.1A devices

simultaneously (2 iPads, or 1 iPad and 1 iPhone, as I use).

And, just for the record, I don't work for, or have any interest in

Anker other than as a very satisfied customer. 



Jim Parker

edpav8r(at)yahoo.com
Guest

Posted: Fri Dec 30, 2016 9:19 am Post subject: USB

There's no way a cord could know the capability of a plug adapter unless the adapter signals it in some way.  The device in Apple's charging cords (and, as Jim pointed out, in MiFi Certified cords) is an integrated circuit used for authentication.  It still looks for the signaling voltages on D+ and D-, which current Apple plug adapters provide.  The plug adapters are still using simple resistor dividers to generate the 2.75V signals.



Eric

 	  Quote: 	
		   On Dec 30, 2016, at 3:43 AM, rampil <ira.rampil(at)gmail.com> wrote:

 At least in the Apple world, the resistor network which informs the device to be charged of the charger's capability and compatibility is actually in the charging cord. If I remember the tech specs, the amperage capacity is detected by voltage drop across the resistor.  Bottom Line:   If you want to charge an iPad or iPhone use a "genuine" Lightning cord.

 

 --------

 Ira N224XS

email(at)jaredyates.com
Guest

Posted: Fri Dec 30, 2016 12:00 pm Post subject: USB

Is this contrary to Joe's advice about sensing voltage across the two USB data pins, or in addition to it?



On Fri, Dec 30, 2016 at 6:43 AM, rampil <ira.rampil(at)gmail.com (ira.rampil(at)gmail.com)> wrote:

 	  Quote: 	
		  --> AeroElectric-List message posted by: "rampil" <ira.rampil(at)gmail.com (ira.rampil(at)gmail.com)>

 

 At least in the Apple world, the resistor network which informs the

 device to be charged of the charger's capability and compatibility is

 actually in the charging cord. If I remember the tech specs, the amperage

 capacity is detected by voltage drop across the resistor.

 Bottom Line:   If you want to charge an iPad or iPhone use a "genuine" Lightning cord.

 

 --------

 Ira N224XS

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=464480#464480

 

 

 

 

 

 

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enginerdy(at)gmail.com
Guest

Posted: Fri Dec 30, 2016 12:24 pm Post subject: USB

This is not correct. The charging resistor network is in the charger.



However if you use a super-cheap charging cord, the wire gauge may not be large enough.



When the iPhone (or whatever) detects the charger voltage drop below a certain voltage (maybe 4.8V?) it will back off until the voltage comes back up.

So based on the resistance of the cable, the device may not be able to charge as quickly as it otherwise would.



Both pieces have to be in place for an optimal charge time.

 	  Quote: 	
		  On Dec 30, 2016, at 5:43 AM, rampil <ira.rampil(at)gmail.com (ira.rampil(at)gmail.com)> wrote:

At least in the Apple world, the resistor network which informs thedevice to be charged of the charger's capability and compatibility isactually in the charging cord

deej(at)deej.net
Guest

Posted: Fri Dec 30, 2016 1:10 pm Post subject: USB

 	  Quote: 	
		   On Dec 30, 2016, at 3:23 PM, Daniel Hooper <enginerdy(at)gmail.com> wrote:

 

 This is not correct. The charging resistor network is in the charger.

 


	


This is not correct.  The charging resistor network is in the cord, not the charger.



You can take a charger that provides a USB powered port, plug a cord without the resistor network into it, and the Apple device will not charge.  Use the same charger with a cord that does have the resistor network, and it will charge fine.



The amp rating of the charger does have an effect on the rate of charge, but the resistor network is not in the charger, it is in the cord.



-Dj

enginerdy(at)gmail.com
Guest

Posted: Fri Dec 30, 2016 1:48 pm Post subject: USB

Maybe this is what you’re talking about?



http://appleinsider.com/articles/12/09/25/apples_lightning_port_dynamically_assigns_pins_to_allow_for_reversible_use



It’s a bad idea to use a non-MFI Lightning cable in any case, for this reason.



But the D+/D- line bias network that tells the phone how fast it is allowed to charge is DEFINITELY located inside the charger.



There are a decent number of standards between the various Apple configurations, newer USB standards, and a Chinese standard, so having an MFI cable for you phone and a Samsung charger is no guarantee of success.



There are chips (ICs) made for chargers out there that can (somehow) sense which kind of device is attached and adjust its resistor network to allow the maximum charging for any type, but it is difficult to tell whether this chip was designed into the charger.

 	  Quote: 	
		  On Dec 30, 2016, at 3:09 PM, Dj Merrill <deej(at)deej.net (deej(at)deej.net)> wrote:

--> AeroElectric-List message posted by: Dj Merrill <deej(at)deej.net (deej(at)deej.net)> 	  Quote: 	
		  On Dec 30, 2016, at 3:23 PM, Daniel Hooper <enginerdy(at)gmail.com (enginerdy(at)gmail.com)> wrote:This is not correct. The charging resistor network is in the charger. 	
This is not correct.  The charging resistor network is in the cord, not the charger.You can take a charger that provides a USB powered port, plug a cord without the resistor network into it, and the Apple device will not charge.  Use the same charger with a cord that does have the resistor network, and it will charge fine.The amp rating of the charger does have an effect on the rate of charge, but the resistor network is not in the charger, it is in the cord.-Djhttp://wiki.matronics.com

deej(at)deej.net
Guest

Posted: Fri Dec 30, 2016 2:48 pm Post subject: USB

On 12/30/2016 4:47 PM, Daniel Hooper wrote:

 	  Quote: 	
		   But the D+/D- line bias network that tells the phone how fast it is

 allowed to charge is DEFINITELY located inside the charger.


	




If you buy a cable that is supposed to plug into a USB port, the 

resistor network is most definitely inside the cable, if for no other 

reason than your computer USB port (ie, the charger aka power source) is 

not customized for Apple devices.  This is true for both the older style 

plugs (iphone 4s and earlier for example) and the new lightning 

connector for the later devices.  In addition, the newer lightning 

connector has other circuitry built into it like the MFi authorization chip.



You might be able to buy a charger that has the resistive network built 

into it, but from what I've seen it is common to put this inside the 

cable such that the cable can then be used with any charger that offers 

a USB port.



Here is an example of a lightning cable that has it built in:

https://www.amazon.com/Anker-PowerLine-Lightning-Certified-Charger/dp/B013JMBAMC/



Here is an example of an older iPhone 4s cable that has it built in:

https://www.amazon.com/iPhone-JETech-3-Pack-Certified-Charging/dp/B015V7XB5C/



I haven't seen a charger that has the resistive network built into it, 

and didn't find one from a quick search on Amazon.  Can you offer a link 

that has this in the charger itself, and not the cable?



Thanks,



-Dj



-- 

Dj Merrill - N1JOV - EAA Chapter 87

Sportsman 2+2 Builder #7118 N421DJ - http://deej.net/sportsman/

Glastar Flyer N866RH - http://deej.net/glastar/

deej(at)deej.net
Guest

Posted: Fri Dec 30, 2016 3:10 pm Post subject: USB

To make it even more confusing, there are differences in USB 1, 2, and 

DCP (Dedicated Charging Port) which also have different resistor 

networks across D+ and D-.  However, Apple, in its infinite wisdom 

(sarcasm) didn't use the standards, thus causing one to have to buy 

special USB cables to be recognized as one that would actually charge 

the device, otherwise you get "Charging is not supported with this 

accessory" or similar message on the iPhone.



That special resistor network built into the cables what we are 

referring to, if that helps to clarify things.



-Dj

-- 

Dj Merrill - N1JOV - EAA Chapter 87

Sportsman 2+2 Builder #7118 N421DJ - http://deej.net/sportsman/

Glastar Flyer N866RH - http://deej.net/glastar/

enginerdy(at)gmail.com
Guest

Posted: Fri Dec 30, 2016 3:12 pm Post subject: USB

If you buy genuine Apple cables they do not have this built in — that is a special cable that potentially tells the iPhone that it can draw more current than the charger may be capable of.

I suspect those items counterfeit MFI for that reason — highly nonstandard. It’s possible that they have loosened the standards for accessory products, but in my experience they keep the leash pretty taut.



The truth is that the resistor network is in EVERY charger that is intended for Apple devices, and some configuration or other (USB charging standard or Chinese charging standard) is present in nearly every other one. Some chargers, as I mentioned before, have a chip that can switch between the standards automatically.



Here is the evidence in Ken Sherriff’s Apple charger teardown:

http://www.righto.com/2012/05/apple-iphone-charger-teardown-quality.html



In the schematic he drew from examination,



http://static.righto.com/files/charger-schematic.pdf



you can see the ID network there on page 2 of the schematic, R5, R6, R7, and R9.



There are also many reference designs for USB chargers that include these or some similar configuration of resistors.



 	  Quote: 	
		  On Dec 30, 2016, at 4:47 PM, Dj Merrill <deej(at)deej.net (deej(at)deej.net)> wrote:

--> AeroElectric-List message posted by: Dj Merrill <deej(at)deej.net (deej(at)deej.net)>On 12/30/2016 4:47 PM, Daniel Hooper wrote: 	  Quote: 	
		  But the D+/D- line bias network that tells the phone how fast it isallowed to charge is DEFINITELY located inside the charger. 	
If you buy a cable that is supposed to plug into a USB port, the resistor network is most definitely inside the cable, if for no other reason than your computer USB port (ie, the charger aka power source) is not customized for Apple devices.  This is true for both the older style plugs (iphone 4s and earlier for example) and the new lightning connector for the later devices.  In addition, the newer lightning connector has other circuitry built into it like the MFi authorization chip.You might be able to buy a charger that has the resistive network built into it, but from what I've seen it is common to put this inside the cable such that the cable can then be used with any charger that offers a USB port.Here is an example of a lightning cable that has it built in:https://www.amazon.com/Anker-PowerLine-Lightning-Certified-Charger/dp/B013JMBAMC/Here is an example of an older iPhone 4s cable that has it built in:https://www.amazon.com/iPhone-JETech-3-Pack-Certified-Charging/dp/B015V7XB5C/I haven't seen a charger that has the resistive network built into it, and didn't find one from a quick search on Amazon.  Can you offer a link that has this in the charger itself, and not the cable?Thanks,-Dj-- Dj Merrill - N1JOV - EAA Chapter 87Sportsman 2+2 Builder #7118 N421DJ - http://deej.net/sportsman/Glastar Flyer N866RH - http://deej.net/glastar/

enginerdy(at)gmail.com
Guest

Posted: Fri Dec 30, 2016 3:21 pm Post subject: USB

Read what this guy has to say about it. I haven’t used his products, so I can’t vouch for them, but I heard him give a talk at Oshkosh about USB charging and it was right on.



These products you have here are what he calls a “cheater cable”.



He even has an “intelligent charger” module that (I believe) has the smart resistor switching IC in it.



http://www.commitlift.com/usbchargers.html

Sidenote: “Adaptive Fast Charging” that he talks about is a whole different mess….



 	  Quote: 	
		  On Dec 30, 2016, at 4:47 PM, Dj Merrill <deej(at)deej.net (deej(at)deej.net)> wrote:

--> AeroElectric-List message posted by: Dj Merrill <deej(at)deej.net (deej(at)deej.net)>On 12/30/2016 4:47 PM, Daniel Hooper wrote: 	  Quote: 	
		  But the D+/D- line bias network that tells the phone how fast it isallowed to charge is DEFINITELY located inside the charger. 	
If you buy a cable that is supposed to plug into a USB port, the resistor network is most definitely inside the cable, if for no other reason than your computer USB port (ie, the charger aka power source) is not customized for Apple devices.  This is true for both the older style plugs (iphone 4s and earlier for example) and the new lightning connector for the later devices.  In addition, the newer lightning connector has other circuitry built into it like the MFi authorization chip.You might be able to buy a charger that has the resistive network built into it, but from what I've seen it is common to put this inside the cable such that the cable can then be used with any charger that offers a USB port.Here is an example of a lightning cable that has it built in:https://www.amazon.com/Anker-PowerLine-Lightning-Certified-Charger/dp/B013JMBAMC/Here is an example of an older iPhone 4s cable that has it built in:https://www.amazon.com/iPhone-JETech-3-Pack-Certified-Charging/dp/B015V7XB5C/I haven't seen a charger that has the resistive network built into it, and didn't find one from a quick search on Amazon.  Can you offer a link that has this in the charger itself, and not the cable?Thanks,-Dj-- Dj Merrill - N1JOV - EAA Chapter 87Sportsman 2+2 Builder #7118 N421DJ - http://deej.net/sportsman/Glastar Flyer N866RH - http://deej.net/glastar/

deej(at)deej.net
Guest

Posted: Fri Dec 30, 2016 4:29 pm Post subject: USB

On 12/30/2016 6:11 PM, Daniel Hooper wrote:

 	  Quote: 	
		   If you buy genuine Apple cables they do not have this built in


	


My curiosity was piqued so I conducted a couple of experiments.



I took a genuine Apple cable that works with my Apple charger for an 

iPhone 4s, and plugged it into a Windows 7 PC USB port.  It seems to 

work fine, and charges the iPhone 4s without displaying any error 

messages on the screen.



I repeated the same test with an Apple lightning cable and Iphone SE 

with the same results.



If there wasn't anything built into the cable, how did this work 

properly?  Let's find out.



This video gives a good explanation of how the Apple protocol works with 

regards to the resistive network used for the iPhone 4s:



https://learn.adafruit.com/minty-boost/icharging?embeds=allow



We know that the different USB ports (USB 1, 2, 3, etc) offer different 

power ratings (https://en.wikipedia.org/wiki/USB).  The power rating is 

identified by using different resistances related to the two data pins, 

(D+ and D-).



It would appear that the iPhone recognizes the standard USB 

identification resistances, and can therefore use a standard USB port to 

charge.  In addition, Apple has another set of proprietary resistances 

that identify power ratings that are different than the USB standard, 

and they use these in their chargers.



So, the answer to my question above is that it worked because in all of 

my test cases there were resistors across the data lines, both in the 

USB ports and the Apple charger.



I stand corrected, and the only explanation is that the resistive 

network indeed exists within the charger, not the cable.  The "cheater 

cables" you refer to were for using non-Apple chargers, whether wall 

chargers or the "cigarette lighter" variety that had no resistance 

across the data lines, and the resistors were added in the cable so the 

iPhone would work.  I actually built one of these cables years ago, and 

made the incorrect conclusion that the resistive network identifier was 

in all the cables.

-- 

Dj Merrill - N1JOV - EAA Chapter 87

Sportsman 2+2 Builder #7118 N421DJ - http://deej.net/sportsman/

Glastar Flyer N866RH - http://deej.net/glastar/

enginerdy(at)gmail.com
Guest

Posted: Fri Dec 30, 2016 5:00 pm Post subject: USB

Thank you for taking the time to understand what is going on here.



It’s fairly complicated and the non-standard hardware that people use to get around all sorts of issues only makes it worse.



For what it’s worth, Apple has been using the line bias resistors since before there was a USB charging standard.



There’s one last point that you’ve got a little wonky:

 	  Quote: 	
		  On Dec 30, 2016, at 6:28 PM, Dj Merrill <deej(at)deej.net (deej(at)deej.net)> wrote:

It would appear that the iPhone recognizes the standard USB identification resistances

	




Your test by plugging your phone into a computer doesn’t tell you everything you want to know.



Computer ports have a fully digital power-negotiation protocol that is built into the original USB 1.0 standard (up to 500mA). Because of this extra hardware, the computer port does not need charger ID resistors.



There are SOME computers that have a type of dedicated charging port that can serve even when the computer is turned off, but this is not a typical setup.

In some cases you may get a charging indication with a simple 5V power supply (no USB 2.0 communication, no ID resistors). BUT the phone will only draw around 500mA if it does anything. This is not enough current to keep the battery charged with the screen on, so the battery will slowly run down even though it is indicating a charge.



What the ID resistors do is tell the phone “hey, go nuts! I’ve got 1A (or 2A or 2.1A) for you here!”, which will charge the phone with various levels of speed.



The real struggle is getting the optimum charging rate out of your charger, no matter what device you have. That’s the holy grail, and you have to spend a few bucks to get that functionality in a charger. (also assuming you aren’t using a crappy cable)



There’s no great way to test for this function as a consumer and there’s no real standard way for manufacturers to communicate that functionality effectively, since so many of the cheap ones lie about what they do.

email(at)jaredyates.com
Guest

Posted: Fri Dec 30, 2016 5:36 pm Post subject: USB

This has all been really useful discussion, thank you! To take it from the theoretical to the actionable (I'm ready to get out my soldering iron), do we have a specific list of resistors and a schematic to get the appropriate volts on the data pins if we use something like the 5v power supply that Joe linked in the beginning of the discussion? It seems that there's no need for all of us to do the trial and error if we have the same volts coming in and the same device connected to the plug.



On Fri, Dec 30, 2016 at 7:59 PM, Daniel Hooper <enginerdy(at)gmail.com (enginerdy(at)gmail.com)> wrote:

 	  Quote: 	
		  Thank you for taking the time to understand what is going on here.

It’s fairly complicated and the non-standard hardware that people use to get around all sorts of issues only makes it worse.

For what it’s worth, Apple has been using the line bias resistors since before there was a USB charging standard.

There’s one last point that you’ve got a little wonky:



 	  Quote: 	
		  On Dec 30, 2016, at 6:28 PM, Dj Merrill <deej(at)deej.net (deej(at)deej.net)> wrote:

It would appear that the iPhone recognizes the standard USB identification resistances

	




Your test by plugging your phone into a computer doesn’t tell you everything you want to know.

Computer ports have a fully digital power-negotiation protocol that is built into the original USB 1.0 standard (up to 500mA). Because of this extra hardware, the computer port does not need charger ID resistors.

There are SOME computers that have a type of dedicated charging port that can serve even when the computer is turned off, but this is not a typical setup.





In some cases you may get a charging indication with a simple 5V power supply (no USB 2.0 communication, no ID resistors). BUT the phone will only draw around 500mA if it does anything. This is not enough current to keep the battery charged with the screen on, so the battery will slowly run down even though it is indicating a charge.

What the ID resistors do is tell the phone “hey, go nuts! I’ve got 1A (or 2A or 2.1A) for you here!”, which will charge the phone with various levels of speed.

The real struggle is getting the optimum charging rate out of your charger, no matter what device you have. That’s the holy grail, and you have to spend a few bucks to get that functionality in a charger. (also assuming you aren’t using a crappy cable)

There’s no great way to test for this function as a consumer and there’s no real standard way for manufacturers to communicate that functionality effectively, since so many of the cheap ones lie about what they do.

edpav8r(at)yahoo.com
Guest

Posted: Fri Dec 30, 2016 11:12 pm Post subject: USB

Jared,

This thread was somehow split from the original post on this subject a few days ago.  If you look at the original thread, here...

http://forums.matronics.com/viewtopic.php?t=16765274

...in the 6th message I described exactly the info you're looking for.

Another option, if you have the ability to lay out and solder a circuit board using surface mount components, is to use an IC like the Texas Instruments TPS2513A or TPS2514A:

http://www.ti.com/lit/ds/symlink/tps2514.pdf

Eric



On Dec 30, 2016, at 5:34 PM, Jared Yates <email(at)jaredyates.com (email(at)jaredyates.com)> wrote:



 	  Quote: 	
		  This has all been really useful discussion, thank you! To take it from the theoretical to the actionable (I'm ready to get out my soldering iron), do we have a specific list of resistors and a schematic to get the appropriate volts on the data pins if we use something like the 5v power supply that Joe linked in the beginning of the discussion? It seems that there's no need for all of us to do the trial and error if we have the same volts coming in and the same device connected to the plug.

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