I thought the data line was used to signal what current the device requires and what the power supply or computer USB socket is capable of. But aren't charging cables missing the data lines?

On 11/11/2022 8:59 PM, Commander Kinsey wrote:
> I thought the data line was used to signal what current the device requires and what the power supply or computer USB socket is capable of.  But aren't charging cables missing the data lines?

This isn't the whole story, but it'll fill in what some
of the other sites miss. USB-PD spec is another way to do it,
instead of some of these other earlier attempts.

https://obddiag.net/usb-power.html

That makes it easier to understand why
a cable might matter. As demonstrated here.
It's too bad the chart does not have a column
for the "suspected charging standard" used in each
case. If they had included some names, it would
make it easier for you to Google each
(proprietary or otherwise) standard.

https://www.extremetech.com/wp-content/uploads/2017/04/USB-FastCharging-640x419.png

Other cabling schemes may use more "active"
means of signaling. "Passive" cabling (where
there is no D+ D- continuity, but there is resistor
straps on D+ D- on the cable output end) are generally
limited to lower currents.

If you have a 1 ampere wall adapter, and you
use a "charging cable that indicates 2 amperes",
then plugging your iPad into that, the iPad believes
the 2 ampere resistor-strap-indication and draws
the 2 amperes, and the wall adapter... shuts off
on overcurrent. You cannot necessarily join just
any old random cable between wall adapter and device.
The combinations must be intelligently selected by the
person doing this. When using one of the active cable
standards, the hope is the automation avoids
some of the potential issues. Just because one end
of your setup supports USB PD, does not mean the other
end does. You could even join two USB PD devices
with *the wrong cable*.

If you use a USB extension cable, with just the four wires
and no resistors whatsoever, then I would expect the
charging current to be one ampere or less.

I think it would take a significant number of web page
URLs, to cover all the methods. Start Googling :-)

Paul

On Sat, 12 Nov 2022 04:03:04 -0000, Paul <nospam@needed.invalid> wrote:

> On 11/11/2022 8:59 PM, Commander Kinsey wrote:
>> I thought the data line was used to signal what current the device requires and what the power supply or computer USB socket is capable of. But aren't charging cables missing the data lines?
>
> This isn't the whole story, but it'll fill in what some
> of the other sites miss. USB-PD spec is another way to do it,
> instead of some of these other earlier attempts.
>
> https://obddiag.net/usb-power.html

Interesting, they say "Samsung devices require 1.2V voltage on both D+ and D- data lines". I have a Samsung phone which will not charge off one particular 3.1A power supply, but it's happy with anything else. Even 500mA chargers below it's max current. And the weird thing is it works with a "charging cable" which presumably has no data lines, so it can't possibly need a voltage on them.

> That makes it easier to understand why
> a cable might matter. As demonstrated here.
> It's too bad the chart does not have a column
> for the "suspected charging standard" used in each
> case. If they had included some names, it would
> make it easier for you to Google each
> (proprietary or otherwise) standard.
>
> https://www.extremetech.com/wp-content/uploads/2017/04/USB-FastCharging-640x419.png

So Google and Samsung are in bed together and are pushing out anything else?

I have a Samsung A10, which no matter what I power it with it only takes 1.1A. But I don't have a genuine Samsung charger. Why? Because they don't supply them with the phone! It just says use any charger you have lying about!

I can't find anywhere what the max charging rate of an A10 is, amazing its not in some specs sheet somewhere! I had to use "Ampere", an app to monitor battery charging rate, to work out how much it was taking from various sources.

> Other cabling schemes may use more "active"
> means of signaling. "Passive" cabling (where
> there is no D+ D- continuity, but there is resistor
> straps on D+ D- on the cable output end) are generally
> limited to lower currents.

WTF? These are charging cables, specifically designed to charge! No data lines, fast charging expected!

> If you have a 1 ampere wall adapter, and you
> use a "charging cable that indicates 2 amperes",
> then plugging your iPad into that, the iPad believes
> the 2 ampere resistor-strap-indication and draws
> the 2 amperes, and the wall adapter... shuts off
> on overcurrent.

I've never found an adaptor to do that, the voltage just drops, so the charging current ends up what it should be.

> You cannot necessarily join just
> any old random cable between wall adapter and device.
> The combinations must be intelligently selected by the
> person doing this. When using one of the active cable
> standards, the hope is the automation avoids
> some of the potential issues. Just because one end
> of your setup supports USB PD, does not mean the other
> end does. You could even join two USB PD devices
> with *the wrong cable*.
>
> If you use a USB extension cable, with just the four wires
> and no resistors whatsoever, then I would expect the
> charging current to be one ampere or less.

But you'd still have the resistors in the actual cable plugged into the extension cable.

> I think it would take a significant number of web page
> URLs, to cover all the methods. Start Googling :-)

I thought USB was supposed to just work.

Well I've ordered a Nokia 3A charger, we'll see what that does.

Why the hell aren't all these devices using charging pads yet? An electric toothbrush I got decades ago charges by induction. It's not an expensive method.

On 11/12/2022 1:37 AM, Commander Kinsey wrote:

>
> Why the hell aren't all these devices using charging pads yet?

  An electric toothbrush I got decades ago charges by induction.

It's not an expensive method.

On electronics, this is the inductive charging standard. "Qi"

https://en.wikipedia.org/wiki/Qi_%28standard%29

Paul

On Saturday, November 12, 2022 at 2:37:14 AM UTC-4, Commander Kinsey wrote:
> On Sat, 12 Nov 2022 04:03:04 -0000, Paul <nos...@needed.invalid> wrote:
>
> > On 11/11/2022 8:59 PM, Commander Kinsey wrote:
> >> I thought the data line was used to signal what current the device requires and what the power supply or computer USB socket is capable of. But aren't charging cables missing the data lines?
> >
> > This isn't the whole story, but it'll fill in what some
> > of the other sites miss. USB-PD spec is another way to do it,
> > instead of some of these other earlier attempts.
> >
> > https://obddiag.net/usb-power.html
> Interesting, they say "Samsung devices require 1.2V voltage on both D+ and D- data lines". I have a Samsung phone which will not charge off one particular 3.1A power supply, but it's happy with anything else. Even 500mA chargers below it's max current. And the weird thing is it works with a "charging cable" which presumably has no data lines, so it can't possibly need a voltage on them.

That is an incorrect assumption, that the charging only cable has nothing on the data pins.

> > That makes it easier to understand why
> > a cable might matter. As demonstrated here.
> > It's too bad the chart does not have a column
> > for the "suspected charging standard" used in each
> > case. If they had included some names, it would
> > make it easier for you to Google each
> > (proprietary or otherwise) standard.
> >
> > https://www.extremetech.com/wp-content/uploads/2017/04/USB-FastCharging-640x419.png
> So Google and Samsung are in bed together and are pushing out anything else?
>
> I have a Samsung A10, which no matter what I power it with it only takes 1.1A. But I don't have a genuine Samsung charger. Why? Because they don't supply them with the phone! It just says use any charger you have lying about!
>
> I can't find anywhere what the max charging rate of an A10 is, amazing its not in some specs sheet somewhere! I had to use "Ampere", an app to monitor battery charging rate, to work out how much it was taking from various sources.

It's a cell phone. What do you expect?

> > Other cabling schemes may use more "active"
> > means of signaling. "Passive" cabling (where
> > there is no D+ D- continuity, but there is resistor
> > straps on D+ D- on the cable output end) are generally
> > limited to lower currents.
> WTF? These are charging cables, specifically designed to charge! No data lines, fast charging expected!

Try using your ohm meter.

Wouldn't the resistors be in the power unit? It makes no sense to have anything in the cable unless the currents are so high, they would overheat a typical cable.

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209

On Sat, 12 Nov 2022 07:33:18 -0000, Paul <nospam@needed.invalid> wrote:

> On 11/12/2022 1:37 AM, Commander Kinsey wrote:
>
>>
>> Why the hell aren't all these devices using charging pads yet?
>
> An electric toothbrush I got decades ago charges by induction.
>
> It's not an expensive method.
>
> On electronics, this is the inductive charging standard. "Qi"
>
> https://en.wikipedia.org/wiki/Qi_%28standard%29

So why isn't it in every single phone?

On Sat, 12 Nov 2022 07:39:17 -0000, Ricky <gnuarm.deletethisbit@gmail.com> wrote:

> On Saturday, November 12, 2022 at 2:37:14 AM UTC-4, Commander Kinsey wrote:
>> On Sat, 12 Nov 2022 04:03:04 -0000, Paul <nos...@needed.invalid> wrote:
>>
>> > On 11/11/2022 8:59 PM, Commander Kinsey wrote:
>> >> I thought the data line was used to signal what current the device requires and what the power supply or computer USB socket is capable of. But aren't charging cables missing the data lines?
>> >
>> > This isn't the whole story, but it'll fill in what some
>> > of the other sites miss. USB-PD spec is another way to do it,
>> > instead of some of these other earlier attempts.
>> >
>> > https://obddiag.net/usb-power.html
>> Interesting, they say "Samsung devices require 1.2V voltage on both D+ and D- data lines". I have a Samsung phone which will not charge off one particular 3.1A power supply, but it's happy with anything else. Even 500mA chargers below it's max current. And the weird thing is it works with a "charging cable" which presumably has no data lines, so it can't possibly need a voltage on them.
>
> That is an incorrect assumption, that the charging only cable has nothing on the data pins.

Shouldn't there be some kind of standard for charging? It seems every manufacturer uses a different technique.

>> > That makes it easier to understand why
>> > a cable might matter. As demonstrated here.
>> > It's too bad the chart does not have a column
>> > for the "suspected charging standard" used in each
>> > case. If they had included some names, it would
>> > make it easier for you to Google each
>> > (proprietary or otherwise) standard.
>> >
>> > https://www.extremetech.com/wp-content/uploads/2017/04/USB-FastCharging-640x419.png
>> So Google and Samsung are in bed together and are pushing out anything else?
>>
>> I have a Samsung A10, which no matter what I power it with it only takes 1.1A. But I don't have a genuine Samsung charger. Why? Because they don't supply them with the phone! It just says use any charger you have lying about!
>>
>> I can't find anywhere what the max charging rate of an A10 is, amazing its not in some specs sheet somewhere! I had to use "Ampere", an app to monitor battery charging rate, to work out how much it was taking from various sources.
>
> It's a cell phone. What do you expect?

Basic specs in the fucking manual, why wouldn't I expect that? I can see the power consumption of my microwave by looking at the rating plate on the back.

>> > Other cabling schemes may use more "active"
>> > means of signaling. "Passive" cabling (where
>> > there is no D+ D- continuity, but there is resistor
>> > straps on D+ D- on the cable output end) are generally
>> > limited to lower currents.
>> WTF? These are charging cables, specifically designed to charge! No data lines, fast charging expected!
>
> Try using your ohm meter.
>
> Wouldn't the resistors be in the power unit? It makes no sense to have anything in the cable unless the currents are so high, they would overheat a typical cable.

Power unit? But what if I use a charging cable on a PC?

Just what is the difference between a charging cable and a data cable?

On Sat, 12 Nov 2022 07:39:17 -0000, Ricky <gnuarm.deletethisbit@gmail.com> wrote:

> On Saturday, November 12, 2022 at 2:37:14 AM UTC-4, Commander Kinsey wrote:
>> On Sat, 12 Nov 2022 04:03:04 -0000, Paul <nos...@needed.invalid> wrote:
>>
>> > Other cabling schemes may use more "active"
>> > means of signaling. "Passive" cabling (where
>> > there is no D+ D- continuity, but there is resistor
>> > straps on D+ D- on the cable output end) are generally
>> > limited to lower currents.
>> WTF? These are charging cables, specifically designed to charge! No data lines, fast charging expected!
>
> Try using your ohm meter.
>
> Wouldn't the resistors be in the power unit? It makes no sense to have anything in the cable unless the currents are so high, they would overheat a typical cable.

Charging cables have no connection on the data lines, they advertise them as being secure - you can charge your phone on an aeroplane or in a cafe without risking someone hacking into your phone. So resistors on data lines within the power supply cannot possibly do anything if you're using a charging cable.

So.... how does a device and power supply work out what rate to charge? In the absence of data lines, does the device just go for it flat out until the voltage drop on the power supply causes it to use less?

On Saturday, 12 November 2022 at 08:57:35 UTC, Commander Kinsey wrote:
> On Sat, 12 Nov 2022 07:39:17 -0000, Ricky <gnuarm.del...@gmail.com> wrote:
> > On Saturday, November 12, 2022 at 2:37:14 AM UTC-4, Commander Kinsey wrote:
> >> On Sat, 12 Nov 2022 04:03:04 -0000, Paul <nos...@needed.invalid> wrote:
> >>
> >> > Other cabling schemes may use more "active"
> >> > means of signaling. "Passive" cabling (where
> >> > there is no D+ D- continuity, but there is resistor
> >> > straps on D+ D- on the cable output end) are generally
> >> > limited to lower currents.
> >> WTF? These are charging cables, specifically designed to charge! No data lines, fast charging expected!
> >
> > Try using your ohm meter.
> >
> > Wouldn't the resistors be in the power unit? It makes no sense to have anything in the cable unless the currents are so high, they would overheat a typical cable.
> Charging cables have no connection on the data lines, they advertise them as being secure - you can charge your phone on an aeroplane or in a cafe without risking someone hacking into your phone. So resistors on data lines within the power supply cannot possibly do anything if you're using a charging cable.
>
> So.... how does a device and power supply work out what rate to charge? In the absence of data lines, does the device just go for it flat out until the voltage drop on the power supply causes it to use less?

Yes, that is exactly what happens with older chargers. Things get more complex with PD
chargers as the voltage can be negotiated. All chargers start at 5V but some can also
deliver 9V, 12V, 15V and 20V and in some cases lots of smaller steps in between.
My pixel3a phone likes to charge at 9V for example. I have a notebook PC that prefers to
charge at 20V. if it can.
Very high power USB chargers can deliver up to 48V at up to 5A giving a maximum output
power of 240W.
The more exotic combinations (more than 20V or more than 3A) will only work with special
cables that have identity chips which specify the current and voltage rating of the cable and
connectors.

John

In article <op.1vii51bbmvhs6z@ryzen.home>, Commander Kinsey
<CK1@nospam.com> wrote:

> Charging cables have no connection on the data lines, they advertise them as
> being secure - you can charge your phone on an aeroplane or in a cafe without
> risking someone hacking into your phone. So resistors on data lines within
> the power supply cannot possibly do anything if you're using a charging
> cable.
>
> So.... how does a device and power supply work out what rate to charge? In
> the absence of data lines, does the device just go for it flat out until the
> voltage drop on the power supply causes it to use less?

usb 'charging' cables are non-compliant with the spec so anything goes.

if the devices and chargers are also non-compliant, then you probably
will get higher rates, because they're not checking for anything. good
luck.

if the devices and chargers are compliant (which most are), then it's
either 100ma (guaranteed minimum) or possibly higher if the cable has
resistors, which are also in the charger but can't be seen because
there aren't any data wires. in other words, the cable is faking it.

the problem is that the cable has no idea what the capability of the
charger will be. a compliant charger has resistors for whatever its
maximum is, but the cable doesn't know what that is. for example, the
cable might indicate 500ma, when the charger is capable of more, or
worse, the cable might indicate 1a and the charger can't source that
much.

tl;dr - avoid 'charging' cables.

On Saturday, 12 November 2022 at 16:59:52 UTC, JNugent wrote:
> On 12/11/2022 04:52 pm, Commander Kinsey wrote:
> > On Sat, 12 Nov 2022 16:33:32 -0000, JNugent <jennin...@mail.com> wrote:
> >
> >> On 12/11/2022 04:21 pm, Commander Kinsey wrote:
> >>> On Sat, 12 Nov 2022 16:00:20 -0000, JNugent <jennin...@mail.com>
> >>> wrote:
> >>>
> >>>> On 12/11/2022 12:03 pm, Commander Kinsey wrote:
> >>>>> On Sat, 12 Nov 2022 11:15:00 -0000, John Walliker
> >>>>> <jrwal...@gmail.com>
> >>>>> wrote:
> >>>>>
> >>>>>> On Saturday, 12 November 2022 at 08:57:35 UTC, Commander Kinsey
> >>>>>> wrote:
> >>>>>>> On Sat, 12 Nov 2022 07:39:17 -0000, Ricky <gnuarm.del...@gmail.com>
> >>>>>>> wrote:
> >>>>>>> > On Saturday, November 12, 2022 at 2:37:14 AM UTC-4, Commander
> >>>>>>> Kinsey wrote:
> >>>>>>> >> On Sat, 12 Nov 2022 04:03:04 -0000, Paul <nos...@needed.invalid>
> >>>>>>> wrote:
> >>>>>>> >>
> >>>>>>> >> > Other cabling schemes may use more "active"
> >>>>>>> >> > means of signaling. "Passive" cabling (where
> >>>>>>> >> > there is no D+ D- continuity, but there is resistor
> >>>>>>> >> > straps on D+ D- on the cable output end) are generally
> >>>>>>> >> > limited to lower currents.
> >>>>>>> >> WTF? These are charging cables, specifically designed to charge!
> >>>>>>> No data lines, fast charging expected!
> >>>>>>> >
> >>>>>>> > Try using your ohm meter.
> >>>>>>> >
> >>>>>>> > Wouldn't the resistors be in the power unit? It makes no sense to
> >>>>>>> have anything in the cable unless the currents are so high, they
> >>>>>>> would overheat a typical cable.
> >>>>>>> Charging cables have no connection on the data lines, they advertise
> >>>>>>> them as being secure - you can charge your phone on an aeroplane or
> >>>>>>> in a cafe without risking someone hacking into your phone. So
> >>>>>>> resistors on data lines within the power supply cannot possibly do
> >>>>>>> anything if you're using a charging cable.
> >>>>>>>
> >>>>>>> So.... how does a device and power supply work out what rate to
> >>>>>>> charge? In the absence of data lines, does the device just go for it
> >>>>>>> flat out until the voltage drop on the power supply causes it to use
> >>>>>>> less?
> >>>>>>
> >>>>>> Yes, that is exactly what happens with older chargers.
> >>>>>
> >>>>> There were some modems back in the days of USB 2, which drew about
> >>>>> 570mA. Some motherboards were shutting the USB socket off when
> >>>>> they did
> >>>>> that.
> >>>>>
> >>>>>> Things get more complex with PD
> >>>>>> chargers as the voltage can be negotiated. All chargers start at 5V
> >>>>>> but some can also
> >>>>>> deliver 9V, 12V, 15V and 20V and in some cases lots of smaller steps
> >>>>>> in between.
> >>>>>> My pixel3a phone likes to charge at 9V for example. I have a
> >>>>>> notebook
> >>>>>> PC that prefers to
> >>>>>> charge at 20V. if it can.
> >>>>>> Very high power USB chargers can deliver up to 48V at up to 5A giving
> >>>>>> a maximum output
> >>>>>> power of 240W.
> >>>>>> The more exotic combinations (more than 20V or more than 3A) will
> >>>>>> only
> >>>>>> work with special
> >>>>>> cables that have identity chips which specify the current and voltage
> >>>>>> rating of the cable and
> >>>>>> connectors.
> >>>>>
> >>>>> Grrrr. My phone takes no more than 5V 1.1A. Takes quite a while to
> >>>>> charge if the CPU is running flat out all 8 cores.
> >>>>
> >>>> Ohm's law?
> >>>
> >>> Nothing to do with it. For some reason Samsung have decided the input
> >>> to the phone shall not exceed 1.1A.
> >>
> >> Really?
> >>
> >> How did they manage to get Ohm's Law repealed?
> >
> > Why do you believe ohms law prevents it drawing 2 amps? 1 amp for the
> > battery to charge and 1 amp for the screen and CPU?
> Do you understand Ohm's law?
>
> What do you understand it to say?
> >>> If the CPU and screen are using
> >>> 750mA, the battery charges very slowly.
> >>
> >> Internal resistance / impedance (depending on whether it is an AC or DC
> >> circuit).
> >
> > You know perfectly well it's DC. Why would they limit the socket to
> > only be able to power the phone or the battery?

There is lots of information here:

https://www.usb.org/usb-charger-pd

John

On Sunday, November 13, 2022 at 3:52:24 AM UTC-8, JNugent wrote:
> On 13/11/2022 10:57 am, The Natural Philosopher wrote:
> > On 12/11/2022 16:33, JNugent wrote:
> >> On 12/11/2022 04:21 pm, Commander Kinsey wrote:

> >>> Nothing to do with it. For some reason Samsung have decided the
> >>> input to the phone shall not exceed 1.1A.
> >>
> >> Really?
> >>
> >> How did they manage to get Ohm's Law repealed?
> >
> > Intelligent semiconductor circuits simply dont obey it.

> Do they reduce the supplied voltage, such that V, I and R stay in balance?

The phone can turn off its various functions; obviously, you turn the touchscreen and
backlight off when you pocket it. Less obviously, it turns off the battery charge circuit
when the battery is full, the radios go silent when 'airplane mode' is selected, and
(on the rare power-down for reset purposes) even turns off its CPU, so
there's a delay next power-up while things reboot.

V is a constant (the charger is a voltage source) even if it can step that constant UP to
different values. I is not constant, because various switch-offs modulate power draw.
R, of course, is... undefined, unless you've paid cellphone prices to
buy ... a resistor.