[SOLVED]..XU4 usb 3 port using usb 2 power output

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[SOLVED]..XU4 usb 3 port using usb 2 power output

Unread postby phaseshifter » Mon Sep 17, 2018 12:17 pm

will the usb 3 port using a usb 2 device give an 800mA power out put

so can it supply 800ma via the usb 3 port..using a usb 2 device to charge some battery`s???

i think that is plain enough to under stand..
Last edited by phaseshifter on Mon Sep 17, 2018 9:58 pm, edited 1 time in total.
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Re: XU4 usb 3 port using usb 2 power output

Unread postby mad_ady » Mon Sep 17, 2018 12:58 pm

I don't see why not. Both usb3 and 2 have the same pins for power. Although - I remember that slave devices need to somehow negotiate current draw with the host, otherwise they are capped at 100mA.
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Re: XU4 usb 3 port using usb 2 power output

Unread postby phaseshifter » Mon Sep 17, 2018 3:34 pm

well the Xu4 was/is capable of driving a hdd via the usb port so my guess was around 500ma
..although the later model boards were capable of like an amp approx from mem after they did a revision change
.. for that very reason higher output currents in the usb line
,,as the cloudshell for xu4 was failing to deliver enough current for the spinners..etc..i just dont exactly remember how much that limit was raised to

and weather the same would apply for a usb 2 device ..current wise..

thank you mad_ady..

i guess i should go read the manual prolly tell me something..and the wiki notes..

my slackness to not do my own work..i should member exactly but i`m getting old..mem not as good as it used to be..
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Re: XU4 usb 3 port using usb 2 power output

Unread postby mad_ady » Mon Sep 17, 2018 3:40 pm

Or you could forget the manual and just experiment :D
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Re: XU4 usb 3 port using usb 2 power output

Unread postby phaseshifter » Mon Sep 17, 2018 4:20 pm

well i got it plugged in and it does charge @ what %tage yet i am to determine..cannot put an ammeter in line if i dont want to hard wire and split the cable..which i really dont want to do..

however it is charging ..weather i could get it to charge at a higher current /speed of charge i dont know..
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Re: XU4 usb 3 port using usb 2 power output

Unread postby mad_ady » Mon Sep 17, 2018 4:59 pm

I guess you can calculate average current if your battery starts drained and you can measure the time it takes to charge... Sadly lsusb -v only shows max power requested by the device, not actual power. Measuring charge time should tell you in an obvious way if it's charging at 100mA, 500mA or 900mA.
Otherwise you'll need something like this: https://www.techtoolsupply.com/USB-3-in ... 20-3pc.htm. You can get them cheaper from aliexpress, but make sure it can measure more than 500mA.
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Re: XU4 usb 3 port using usb 2 power output

Unread postby phaseshifter » Mon Sep 17, 2018 9:57 pm

Thank`s for that looks some handy hardware...


i remembered that the later revision boards blue heatsink/fan have pretty much straight trhough power on the usb-3 ports...it`s coming back to me now..

however i am only running a 4A supply no where i am at present..not my big switch-mode ..

saying that ..the unit requests 800Ma so
i only have the board running the opp sys to boot the kernel and fire up the power to the usb port..


so i can prolly find a 6 or 8A supply round here somewhere..matter of lookin..s much stuff i have for odroid`s in general

any way thanks again....i think i can mark this as solved..even though the true secs were not revealed..
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