How to determine current drawn

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How to determine current drawn

Post by rob2 »

Hi,

I plan to use the 8GB RAM variant of M1 as brains of my graphics tablet. I want the setup to be portable.

I want to connect SATA SSD, USB for tablet, USB for WiFi, and HDMI for tablet.

How can I measure the current that will be drawn by this setup?

I have a separate QC powerbank providing power to the graphics tablet.

On a more holistic level - does anyone have previous experience running a battery powered M1 with few peripherals attached?

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Re: How to determine current drawn

Post by odroid »

First check the average & peak power consumption of your LCD display in your setup.

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Re: How to determine current drawn

Post by mctom »

If I understand your question correctly, you want to know more about tools and methods.

I highly recommend Smart Power 3, which is discounted 50% right now:
https://www.hardkernel.com/shop/smartpower-iii/
It is a power supply that also accurately measures current and power draw. I use it for all my power consumption measurements these days.
It also lets you record results via USB or WiFi.

I haven't tried running M1 on a battery, but even if I did I wouldn't use powerbank for it - but that's just my way of building things, there's nothing wrong with this approach.
I would suggest hooking up your whole setup together except powerbank, and measuring the power draw with SmartPower 3.
Alternatively you can use any other power supply, voltmeter and ammeter, and do some math. But since you're asking, I assume you'd rather get a dedicated device for this task.

It's up to you to improve the results. You can underclock CPU, disable unused peripherals, but as @odroid hints, the display backlight might be the top energy consumer, just like it's been in laptops and mobile devices for past decade.

SATA SSD also may be hungry for power, I would totally use eMMC module instead. It is slightly slower, but has been specifically designed as mass storage for mobile devices.
If you choose eMMC, then you may as well try M1S instead, which is smaller and cheaper, and comes with 64GB eMMC already built in. My usual idle power draw is 1.4W, but I never attempted to improve it.
For additional storage, if you need it, you could use SD card and mount it as your /home directory.
8GB of RAM will compensate for storage slowness anyway, as Linux by default caches storage data in unused regions of RAM.
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Re: How to determine current drawn

Post by rob2 »

Hi, thanks for moving the post to correct board.

I can't use PayPal, so can't order from odroid.

But I've ordered USB ammeter voltmeter and will share my findings soon.

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Re: How to determine current drawn

Post by mad_ady »

rob2 wrote:Hi, thanks for moving the post to correct board.

I can't use PayPal, so can't order from odroid.

But I've ordered USB ammeter voltmeter and will share my findings soon.
Are you able to power your desired board + screen from 5V?
The M1S needs 5V 3A, but M1 needs 12+V
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Re: How to determine current drawn

Post by L67GS »

rob2 wrote:
Tue Feb 06, 2024 2:14 am
Hi, thanks for moving the post to correct board.

I can't use PayPal, so can't order from odroid.

But I've ordered USB ammeter voltmeter and will share my findings soon.
This is a misconception, the PayPal system has a guest checkout so you can pay with more conventional means like a card.

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Re: How to determine current drawn

Post by mctom »

mad_ady wrote:
Tue Feb 06, 2024 4:17 am
Are you able to power your desired board + screen from 5V?
The M1S needs 5V 3A, but M1 needs 12+V
That's a good point, forgot all about it. Another argument backing M1S I think.
M1 could be powered through boost converter, but that's another source of losses.
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Tue Feb 06, 2024 12:09 pm
This is a misconception, the PayPal system has a guest checkout so you can pay with more conventional means like a card.
That's correct, it's been a while since I ordered anything from HK but certainly we did it without PayPal account. I used my VISA debit card.
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Re: How to determine current drawn

Post by L67GS »

It's been a while since I have done it, but you select PayPal, then instead of logging in there's a guest checkout option of some sort there.

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Re: How to determine current drawn

Post by rob2 »

mad_ady wrote:
Tue Feb 06, 2024 4:17 am
rob2 wrote:Hi, thanks for moving the post to correct board.

I can't use PayPal, so can't order from odroid.

But I've ordered USB ammeter voltmeter and will share my findings soon.
Are you able to power your desired board + screen from 5V?
The M1S needs 5V 3A, but M1 needs 12+V
Wow!

Thanks, @mad_ady I didn't notice 12V requirement, I thought if QC/PD power bank (which I now see are limited to 5-7 V) can power the display tablet it should work with M1 (or any other SBC) also.

I have cancelled my M1 order and might order M1S via PayPal route.

Thanks again for pointing it out. I am good at Python, let me know if I can assist you in any task.
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Re: How to determine current drawn

Post by rob2 »

M1S is using RK3566 instead of RK3568B2 used in M1

From what I could read, RK 3566 doesn't have SHA-1/Trustzone - not sure what it means but looks important.

What else will I be losing if I go with M1S?

My purpose is to provide just enough brains to my drawing tablet so it can run GIMP and firefox

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Re: How to determine current drawn

Post by mctom »

Don't worry about lack of features you don't understand. :) What makes you think this is important for drawing pictures?

If you go with M1S, you'll also lose some 200g of aluminum, not exactly perfect to carry around. It has slightly slower RAM, but this only shows in synthetic benchmarks, nothing you could possibly feel.

Until now your primary use case was drawing, but now that you've thrown in the most demanding consumer task, web browsing, you may want something more than a $60 computer with energy saving CPU.
Even without firefox, my ex was drawing in Krita and she experienced lags even on low end 2-core x64 laptop.

Have you tried GIMP on any ARM platform yet? Don't know what your expectations are, but I don't recall anyone being a digital artist and leaving feedback here..
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Re: How to determine current drawn

Post by rob2 »

mctom wrote:
Tue Feb 06, 2024 7:05 pm
Have you tried GIMP on any ARM platform yet? Don't know what your expectations are, but I don't recall anyone being a digital artist and leaving feedback here..
I actually tried it on some SBC, we are not much into coloring, only sketching; plus habits to keep layer count low, it was smooth.

I will post my final experience with Krita here - forgot to mention Krita.
mctom wrote:
Tue Feb 06, 2024 7:05 pm
Don't worry about lack of features you don't understand. :) What makes you think this is important for drawing pictures?
I thought it was important for HTTPS and login - deviantart and dometika are both HTTPS now.

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Re: How to determine current drawn

Post by mctom »

Even wget these days needs a special switch to download stuff outside https. :)
No worries, web browsing will work on M1(S), as long as you lower your expectations towards heavyweight sites, like social media and youtube. In fact, 8GB RAM will become necessary just for this reason.
If you're testing that drawing software on M1 you'll get a decent indication of experience with M1S as well.

BTW I'm glad to hear deviantart is still relevant.
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Re: How to determine current drawn

Post by rob2 »

odroid wrote:
Mon Feb 05, 2024 11:01 am
First check the average & peak power consumption of your LCD display in your setup.
I am still waiting for the USB Ammeter + Voltmeter thing.

I have a question that might be fatal to this attempt/project:

Image

These tablets come with a combo cable which unifies video (HDMI), touch (USB) and power (also USB) into a single USB-C point.

Both battery banks are USB QC/PD capable. Both the tablet and SBC demand 5V at different currents.

Despite the same voltage, is it possible that current from Battery 1 overflows into SBC/Battery 2? Can it fry the electronics?

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Re: How to determine current drawn

Post by rob2 »

What if voltage requirement of tablet/SBC changes with time.

Maybe when SBC wakes up from sleep. Monitors often go to sleep to save power.

Does a worst case scenario like - software of controller has some exception or bug that causes it to negotiate higher/lower voltage - happen?
Last edited by rob2 on Wed Feb 07, 2024 7:49 pm, edited 1 time in total.

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Re: How to determine current drawn

Post by mctom »

Depends how the tablet cable is made, generally speaking it shouldn't expose 5V through USB2 nor HDMI. In which case there's no risk involved.
There is a small chance that USB2 cable will source 5V - that remains to be tested with voltmeter. It may be trouble once you shut down M1S. But I don't find such a rookie mistake in cable design likely.

Ideally you'd want to power your whole setup from one power bank, for a variety of reasons: It's lighter, easier to charge just one thing.
If you want to use two power banks for extended battery life, or your powerbanks have just one USB output, then consider daisy chaining them - one bank charges another. Better yet, keep your secondary power bank separate ;)

Depending on your tablet's current draw, I see three options:
- Power from power bank directly (Preferred),
- Try powering from M1S' USB3 port (Can be tested)
- This additional USB port seems to be limited to 2A: https://www.hardkernel.com/shop/interna ... d-for-m1s/
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Re: How to determine current drawn

Post by mctom »

rob2 wrote:
Wed Feb 07, 2024 7:40 pm
I am thinking the worst case scenario - software / firmware of SBC / tablet has some exception or bug that sometimes decides to negotiate higher/lower voltage.

Do such things happen? Maybe when SBC wakes up from sleep, is there a change in Voltage?
Voltage negotiation happens only in USB PD (Power Delivery) enabled ports, and I'm sure your tablet and M1S cables don't even have wiring necessary to execute it.

EDIT: Or should I say, I'm sure about M1S, I don't even know what tablet you own. But I can hardly imagine a tablet manufacturer that releases a product frying host USB ports, lol
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Re: How to determine current drawn

Post by rob2 »

mctom wrote:
Wed Feb 07, 2024 7:44 pm
Depends how the tablet cable is made, generally speaking it shouldn't expose 5V through USB2 nor HDMI. In which case there's no risk involved.
There is a small chance that USB2 cable will source 5V - that remains to be tested with voltmeter. It may be trouble once you shut down M1S. But I don't find such a rookie mistake in cable design likely.
I think this could be an issue. I always connect USB-C first, HDMI second, touch-USB (black) third and power-USB (red) last.

On some laptops (gaming or greater than 15.6") the USB for touch is able to single-handedly power on the tablet.

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Re: How to determine current drawn

Post by rob2 »

Also, should I order a USB-C breakout board to check continuity of Vcc of USB-A to A4 / B9 pins of USB-C

I am picking up some terminology and theory, but designing a power bank seems difficult to me.

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Re: How to determine current drawn

Post by mctom »

Well I checked that for you and it looks like both M1 and M1S have USB power switches (which also act as over current protection with some 1.5A limit), and they all offer reverse current blocking. So, trying to push 5V back to USB port should not cause any damage.

So there's no need to check anything with tablet cable anymore.
I checked that after you said that Touch USB cable does have +5V (or VBUS in USB nomenclature). In my opinion it really shouldn't.

My understanding was that you already have a powerbank that you intend to use. Designing one isn't easy, most definitely..

I attach pictures of two options how I'd connect it all together. If your powerbank has two USB outputs, it would be for the best to use them both. Otherwise, see if SBC can power the tablet reliably with its two USB ports.

I'm leaving the graph code for future answers.

Code: Select all

digraph {
	{node [style=dotted] <Aux Power Bank>}
	<Aux Power Bank> -> <Power Bank> [style=dotted]
	<Power Bank> -> <M1S> [label=<USB>]
	<M1S> -> <Tablet> [label=<HDMI>]
	<M1S> -> <Tablet> [label=<Touch(USB2)>]
	<M1S> -> <Tablet> [label=<Power(USB3)>]
}
Attachments
tablet2.png
tablet2.png (28.03 KiB) Viewed 260 times
tablet1.png
tablet1.png (27.88 KiB) Viewed 260 times
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Re: How to determine current drawn

Post by rob2 »

mctom wrote:
Thu Feb 08, 2024 2:54 am
Well I checked that for you and it looks like both M1 and M1S have USB power switches (which also act as over current protection with some 1.5A limit), and they all offer reverse current blocking. So, trying to push 5V back to USB port should not cause any damage.
I am curious, how to find this information - I scanned

https://wiki.odroid.com/odroid-m1s/odroid-m1s

and could not find this info using related terms. Do we have to decipher circuit drawings to extract the 1.5A limit on USB power switch inference. It is mind-blowing!
mctom wrote:
Thu Feb 08, 2024 2:54 am
My understanding was that you already have a powerbank that you intend to use. Designing one isn't easy, most definitely..
Yes yes - I am using my phone charger.
mctom wrote:
Thu Feb 08, 2024 2:54 am
I attach pictures of two options how I'd connect it all together. If your powerbank has two USB outputs, it would be for the best to use them both. Otherwise, see if SBC can power the tablet reliably with its two USB ports.
thanks for introducing me to this diagram as code thing. I am moderately good at python - please let me know if I could assist you in any projects :+1:

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Re: How to determine current drawn

Post by mctom »

SBC description is never complete, because there's too much to be said. I write hardware reviews on this forum every time a new Odroid product is released - they are quite long, but still merely touch the subject. It is a product of months of development, not to be summarized in even 1000 words.
Only schematics give you all the definitive answers. In fact, that's what I appreciate so much about Hardkernel and open source hardware in general.
So I opened them up, found USB ports, then followed the VBUS trace until I found USB switch. Then checked the datasheet of that component. Nothing complicated to me, but I do electronics for the living.
Why it's not a part of SBC specification? Well because USB ports are primarily data ports, not power supplies for tablets. ;)

Your tablet also has power rating, surely, I'd be interested to know that. Two USB cables suggest it might be around 1.5A.

I'll let you know when I need help with Python, thanks for the offer. :)
In case you want to know more, these diagram scripts are interpreted by graphviz package, more specifically "dot".
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Re: How to determine current drawn

Post by rob2 »

mctom wrote:
Thu Feb 08, 2024 2:31 pm
SBC description is never complete ... because USB ports are primarily data ports, not power supplies for tablets. ;)
Ah, that makes sense.
mctom wrote:
Thu Feb 08, 2024 2:31 pm
Your tablet also has power rating, surely, I'd be interested to know that. Two USB cables suggest it might be around 1.5A.
I am using XP Pen Artist Pro (13.3"). Not sure about the power rating of the tablet, but the wall wort that came with the tablet says 5V 2.3A 11.5W

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Re: How to determine current drawn

Post by mctom »

The manufacturer says 2A on their website. :)
Now please tell us what power bank you have.

EDIT: https://www.xp-pen.com/product/artist-13-3-pro.html
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Re: How to determine current drawn

Post by mad_ady »

Note that it says it has drivers that support linux, but they mention only x86_64. If there is anything binary, you might have a hard time getting it to work on aarch64.
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Re: How to determine current drawn

Post by rob2 »

mctom wrote:
Thu Feb 08, 2024 6:54 pm
The manufacturer says 2A on their website. :)
Perhaps 2.3A is just for max brightness case? It is not shown here https://www.xp-pen.com/store/buy/4-in-1 ... cable.html
mctom wrote:
Thu Feb 08, 2024 6:54 pm
Now please tell us what power bank you have.
This one https://www.portronics.com/products/lux ... 7024198880

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Re: How to determine current drawn

Post by rob2 »

mad_ady wrote:
Thu Feb 08, 2024 9:34 pm
Note that it says it has drivers that support linux, but they mention only x86_64. If there is anything binary, you might have a hard time getting it to work on aarch64.
:crying:

Mostly everyone uses OpenTabletDriver (even on Windows and Mac), but you're right - I found this in

Code: Select all

.deb -> control.tar.zst -> control
file

Code: Select all

Package: opentabletdriver
Version: 0.6.4.0-1
Architecture: amd64
Maintainer: X9VoiD <oscar.silvestrexx@gmail.com>
Installed-Size: 24483
Pre-Depends: udev
Depends: libevdev2, libgtk-3-0, dotnet-runtime-6.0, libc6 (>= 2.14), libgcc-s1 (>= 3.0), libstdc++6 (>= 4.4)
...
.NET 7 is available on ARM but I am already thinking this is too technical for me at this time

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Re: How to determine current drawn

Post by rob2 »

mad_ady wrote:
Thu Feb 08, 2024 9:34 pm
Note that it says it has drivers that support linux, but they mention only x86_64. If there is anything binary, you might have a hard time getting it to work on aarch64.
How do you always figure out the critical issue?

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Re: How to determine current drawn

Post by mctom »

I downloaded Ubuntu and Pals driver, it does have some sort of software, but I'm guessing it's for configuring a tablet.
The "driver" is a two-line udev rule file, as far as I can tell.

Nevertheless this is worth confirming on any ARM platform. Well spotted!
rob2 wrote:
Thu Feb 08, 2024 9:48 pm
Perhaps 2.3A is just for max brightness case?
No, it's a reasonable headroom of power source versus declared power consumption.
Devices rarely exceed their rated power consumption, that's what the rating really means. It's meant for the consumers to match a power supply properly.

So I think this should work when plugged to two USB ports in M1S.

This power bank surprised me, it has an output and in/out port, lol..
It doesn't say whether both outputs can work simultaneously, but it should be enough to power both SBC and a tablet.
rob2 wrote:
Thu Feb 08, 2024 9:54 pm
Mensa
Don't recommend that one. ;)
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Re: How to determine current drawn

Post by mad_ady »

How do you always figure out the critical issue?
Only by failing repeatedly, but remembering the cause of the failure Image

Binary drivers aren't necessarily a show stopper. I'd search if he rpi folks made the tablet work, because it's very likely the same method would work on odroids too, or if it's an executable (and not a library), chances are it might work with box64...

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Re: How to determine current drawn

Post by rob2 »

I have a raspberry Pi 4B, I am trying to compile that driver and see how well it works for Xournal++ and if possible GIMP

Is it discouraged/against etiquettes to discuss other products here?
Last edited by rob2 on Mon Feb 12, 2024 9:58 am, edited 1 time in total.

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Re: How to determine current drawn

Post by mctom »

What do you mean by "compiling a driver"?

I'm not making rules here, but I don't think menioning RasPi will earn you a ban. But you may find very few users here that will be able to help you.
According to benchmarks, M1S is very close performance-wise to RasPi4, so you shouldn't be disappointed.
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Re: How to determine current drawn

Post by rob2 »

mctom wrote:
Mon Feb 12, 2024 12:47 am
What do you mean by "compiling a driver"?
The OpenTabletDriver has .deb and .rpm files packaged to run only on 64-bit machine it seems. I will try to build the driver software from source on RPi.

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Re: How to determine current drawn

Post by rob2 »

rob2 wrote:
Thu Feb 08, 2024 12:50 am
mctom wrote:
Wed Feb 07, 2024 7:44 pm
Depends how the tablet cable is made, generally speaking it shouldn't expose 5V through USB2 nor HDMI. In which case there's no risk involved.
There is a small chance that USB2 cable will source 5V - that remains to be tested with voltmeter. It may be trouble once you shut down M1S. But I don't find such a rookie mistake in cable design likely.
I think this could be an issue. I always connect USB-C first, HDMI second, touch-USB (black) third and power-USB (red) last.

On some laptops (gaming or greater than 15.6") the USB for touch is able to single-handedly power on the tablet.
As an aside: I measured the power bank rated at 5V gives 5.0 to 5.4 V; so in a setup like this:

Image

is there anything I can do to safeguard the motherboard hosting the USB for touch signals?

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Re: How to determine current drawn

Post by mctom »

Power converters with no load may sometimes overshoot output voltage slightly. I suppose your measurements were performed directly on the power bank's output with no load. I wouldn't worry about it. Once you connect any load to it, 5.4V should not happen.

I'm glad you found what seems to be open source drivers. In that case I wish you luck. You probably could find a tutorial online if you haven't already.
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