This is a placeholder topic for “USB Mini Hub with Power Switch - OTG Micro-USB” comments.
I need a powered USB hub for a USB 4G modem I want to attach to a Rpi 3B+
The Huawei Modem in question needs more juice than the Rpi USB port can supply to operate reliably
In your product description for this USB hub
https://core-electronics.com.au/usb-mini-hub-with-power-switch-otg-micro-usb.html
You describe a need to cut the red wire from the USB line, if external power is needed.
Cut the red wire is a bit vague.
Any chance you can provide more detail?
Or a how to video?
If this device will do what I need, even if it needs a little modification, I will buy one, probably more than one.
Cheers
Nigel
Hi Nigel,
There aren’t any further directions really. You sever the power connection between the USB hub and the Raspberry Pi, so you aren’t pushing power “backwards” into the RPI through the USB port. I expect “cutting the red wire” is clear once its open and you are looking at it. If it turns out that its not just send us a picture of what it looks like once you get that step and we’ll walk you through it!
If you are going to open the USB hub, you should check to see if the DC in barrel jack is the three pin type, and how easy it would be to modify the hub to disconnect the USB power when the DC plug is inserted.
Should stop a lot of hair pulling months or years from now when you try to re-use the hub elsewhere.
Has anyone actually tried this with a tablet or phone where the OTG
connection is required to make the host act as the master? Does it
charge the host or does the OTG mode prevent the host from accepting the
power that is on offer from the hub? Some people say that the GND and ID pins must be shorted with a resistor rather than a direct short in order for charging to occur while the host is in OTG mode.
Hi Karla,
I’ve used similar products to these with success with Pis and android phones, and found the charge passed through, but without both this product and a range of devices in front of me, I can’t say for sure.
I believe this varies on a device-to-device basis. USB-C rectifies some of these issues so depending on your device that may be an option.
Good luck with the hunt though!
-James
I will not say that the switch on the USB is a basic necessity, but it has a right to exist and is certainly not superfluous.
Can I use this adapter to charge my tablet? I have an older Samsung tablet which I connect to a CAN analyser in my car (to use as a display for the ECU), I would like to be able to charge my tablet at the same time however it only has one usb port. Would this adapter allow for that? Thanks
Hi @Alexander275019, Welcome to the Forums!!!
It may not be the ideal solution as I don’t believe it’s designed to work as expected in this use case.
From the description, Adafruit recommends cutting the 5V line that goes to the MicroUSB connector as to not have two 5V feeds going into a Pi Zero when using external power.
This leads me to believe it may work if you power it with an external 1.7mm DC supply but without knowing the exact internal wiring of the PCB I can’t say for certain that it will work.
Hi Aaron
Decent quality powered USB hubs isolate the parent PC or laptop supply when external power is connected so not to backfeed 5V into the parent supply. This enables power to be supplied from the parent device or external whichever is appropriate.
My philosophy in this situation is if I can’t confirm this operation I purchase something else that I can confirm.
Cheers Bob
Hi @Robert93820,
Here’s the direct quote from the product description to clarify
There is a 1.7mm port for an external power supply but its connected directly to the 5V line so if you need to externally power, Adafruit recommend prying open the case and cutting the red 5V line from the USB connection.
The reason for me not using certain terms that it will work for @Alexander275019 use case is because it isn’t the intended use case for the product and there is a risk that it may not work as expected.
Yes Aaron.
I just now read that. I think the chip is capable of controlling that (not absolutely certain as the data sheet is not quite specific but then again it was a quick look) but it is apparently not implemented.
So this device would not come under the heading of what I interpret as “decent quality”.
Having said that it DOES qualify for being able to confirm this action or the lack of it so I would not brush it off completely if it suited my projected application at the time.
Incidentally the Hub i currently use, Mainly for X-Plane 10 simulator, has 3 USB-2 ports and 4 USB-3 ports and DOES isolate the parent USB power.
Cheers Bob
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