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NanoPi Neo OTG power


mihai.aldea

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Hi guys. I am testing a NanoPi Neo for an IoT project. I ordered one with unsoldered ethernet and USB ports.

I am trying to use a miniature WiFi adapter plugged in the OTG port while powering the board from either the debug +/- pins, or from the 5V bus on the GPIO.

The problem is that no mater what option I choose, the board powers up just fine, I can login using the debug port serial-over-consolem however the WiFi adapter doesn't pop up in the lsusb list.

Using an OTG USB hub with external power, fires up the WiFi, however this is the only working way and my project has to have minimum cable clutter. I need to be able to plug in the NanoPi Neo on a PCB using its GPIO pins as both I/O and mechanical mount and have the WiFi adapter plugged in in the OTG port. I did played a bit with the script.bin but after a couple of hours of trial and error I got nothing, I can't seem to get the OTG port to power the WiFi. I ordered some USB connectors but it will take weeks for them to arrive from China.

I used lots of combinations of 2A power adapters and various thick cables to rule out a voltage drop. I believe the answer lies in some tweak but I don't have any clue.

Does anyone have any idea what to try?

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Seams like NanoPi's microusb don't have direct connection to 5v rail, there is p-mosfet on the way, probably to eliminate short  when connecting to PC with nanoPi powered from external source. So otg port can't provide power to external device.

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Seams like NanoPi's microusb don't have direct connection to 5v rail, there is p-mosfet on the way, probably to eliminate short  when connecting to PC with nanoPi powered from external source. So otg port can't provide power to external device.

 

Well, on one hand, the NanoPi works just fine when powered through the OTG. On the other hand the OTG is not a minimal version of a debug port with only GND/RX/RX. I am supposed to be able to plug stuff in and use it. Why having it if it can't power on the plugged devices?

The only reasonable explanation is that depending on the current flow direction, it cuts it down at a very low value of the output current, like when the plugged device requires more than 20mA or so it cuts it down.

I measured about 300mA usage when powering the board from the OTG port so the only problem is with the current flowing out of the port, not flowing in.

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IF I well understood the use of those 5 pins connectors, pin 4 is supposed to be connected to the ground (pin 5) for host mode. Is this the case with your dongle ?

 

But I have no ID how the port and is actually wired on those card and if it can detect and switch to host mode, and I dont like much these bidirectional power circuits ...

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But I have no ID how the port and is actually wired on those card and if it can detect and switch to host mode, and I dont like much these bidirectional power circuits ...

 

It can, it uses GPIOG12 as the OTG-ID input. That is true for the NanoPi Neo as well as the NanoPi M1. It's right there in the schematic...

 

Greetings,

 

Chris

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