Power the board via the wrong USB port (near hdmi)

Hardware related problems and workarounds

Power the board via the wrong USB port (near hdmi)

Postby noob234 » Tue Sep 23, 2014 2:05 pm

I live in Europe, but got the P1601-DK03 board from USA. The problem was the power supply didn't match our connectors. So I cut the cable and connected an adjustable power supply. Then only one LED was glimming. I think the problem was that the voltage was not stable enough, but this time I did'nt know about it.

Then I attached another host over a micro USB cable to the USB port in the near of the hdmi port. The two green LEDs started shined now and the green Ethernet LED started blinking. Then I attached the power barrel with the 5V.

I know now it is a mistake to attach another USB host to the USB OTG port. I am also a Zedboard user. It was my old habitude to do this. Because there you have the FTDI serial converter direct onboard.

Now I use the other USB port in the near of the barrel connector. I changed the jumper from 12 to 23, attached a powered usb hub and the two green LED are shining, the green Ethernet LEDs are blinking. But my board is still not starting. I am waiting for the usb to ttl converter delivery to debug. What could now be happened with the board? Is maybe the USB OTG port burned but the rest still working or will I never be able to boot now?
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Re: Power the board via the wrong USB port (near hdmi)

Postby noob234 » Tue Sep 23, 2014 4:10 pm

It seems that the USB OTG port is still working!! I can see my pendrive!
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Re: Power the board via the wrong USB port (near hdmi)

Postby sebraa » Wed Sep 24, 2014 12:51 pm

An OTG port can be connected to both a host and a device (not at the same time, though). Most smartphones contain OTG connectors, and you can connect them to computers - or, using adaptor cables, to USB flash drives or mice. ;-)
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Re: Power the board via the wrong USB port (near hdmi)

Postby tingo » Mon Oct 06, 2014 11:12 pm

I see the same as the original poster of this thread: when I connect a micro-usb cable to the connector next to the micro-hdmi connector on the Parallella board, the board powers up and runs (the other end of the usb cable is connected to a powered usb 3.0 hub). I have a Kickstarter board (SKUA101040).
Should the board do this? (power up from the micro-usb connector next to the micro-hdmi connector).
According to the documentation, the micro-usb connector between the Ethernet connector and the barrel connector should be used for power.
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Re: Power the board via the wrong USB port (near hdmi)

Postby 9600 » Tue Oct 07, 2014 7:37 am

tingo wrote:Should the board do this? (power up from the micro-usb connector next to the micro-hdmi connector).


It's not specified for this use, but if it does work it does not necessarily mean that there is a problem with your board.

Certain things may work but are advised against, such as powering a Parallella via the USB connector next to the HDMI one, or powering mains appliances via lengths of rope soaked in salty water :)

According to the documentation, the micro-usb connector between the Ethernet connector and the barrel connector should be used for power.


That's right and powering it via the other one may well invalidate your warranty.

Regards,

Andrew
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Re: Power the board via the wrong USB port (near hdmi)

Postby tingo » Tue Oct 07, 2014 10:48 am

9600 wrote:That's right and powering it via the other one may well invalidate your warranty.

Then one question remains: why does the board accept power through this connector at all? Why aren't the power lines isolated on this connector?
Surely we can't be expected to modify usb cables to use the board?
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