How to modify BBAI not to be powered USB-C connector?

[Geza Kuhmann]

Hi All,

I'd like to make my BBAI so it could only be powered from the J9.5/6 pins, but not from the USB-C connector.

On the other hand, the USB-C connector should stay functional as pure USB connection (using the BBAI as a USB gadget).

Reading the schematic it seems to me that removing diode D81 would exactly do this, but not being a hardware expert, I would be glad if somebody could confirm this.

Thanks,

Geza

[adrianne...@gmail.com]

Hi

I would also like to do the same. I had hoped this could be done in the configuration as opposed to a hardware change.

Geeza - have your tried a "data only" USB cable?

[KenUnix]

Adrianne,

I have heard of USB Cables and USB Charging cables but not a USB Data only cable.

[istvan...@gmail.com]

There's no such things as data only USB cable, the 5V is part of the signalling.

[Robert Forsyth]

Is there still bus powered and self powered devices in USB-C?

Are there signals equivalent to OTG ID?

[adrian...@gmail.com]

Hi Geza,

I was wondering if you made any progress here? 

I took a look at the schematics myself and I agree that by removing D81 you essentially disconnect VDD_TYPE C from VDD_5V.

If you then apply 5v power to VDD_CAPE_5V it connects to VDD_5V through D82 and should power the device.  

I assume you would then boot the device by connecting PWR_BUT or P9.9 to GND. 

Have you tried this? Have you been able to locate D81 on the board? I have downloaded the board.pdf but it is extremely difficult to find specific components. 

Many thanks. 

On Saturday, 6 June 2020 09:41:45 UTC+1, Geza Kuhmann wrote:

[adrian...@gmail.com]

I have found D81 from the silk screen data. Will be removing and trying as a next step. 

[adrian...@gmail.com]

When i removed D81 power was present on VDD_5V but only at about 4.5V which is I guess the voltage drop across D82.

there was no voltage on VDD_3V3 and the device would not startup - even after pressing the power on button.

Has anyone solved this?

[istvan...@gmail.com]

Do you use pins 5&6 (VDD_CAPE_5V) to power the board?

[adrianne...@gmail.com]

I connected pin1 to GND and pin5 for VDD_CAPE

As pins 5 and 6 are connected on the PCB I did not see it necessary to connect power to both pins. 

have you successfully self powered one of these boards?

[istvan...@gmail.com]

I've not yet removed the diode, but otherwise I'm powering my BBAI using a 5V/3A power supply (from OKdo) through pins P9.1+2/5+6.

I read in some topics (like https://groups.google.com/forum/#!topic/beagleboard/Tx9pGjJPZ0A) that one might need a beefier supply or added cap if not powering thru the usb connector, though I'm not sure if this applies to BBAI, too.

[Adrian Hatton]

Does it boot the board as soon as you apply power and without the usb connection?

What happens when it is powered up then you connect the USB? 

Sent from my iPhone

On 3 Jul 2020, at 17:04, istvan...@gmail.com wrote:



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[István Gyürki]

Yes it boots as usual without USB power, I use it as a USB gadget, so I regularly connect/disconnect the USB-C connector while being powered over the pins.

It does not reboot, and there's no momentary glitch either, so as long as one of the two power sources is connected, it runs continuously.

To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/2E7C4DC0-3F8D-4CF1-A3C1-2E92513F5ED8%40gmail.com.

[Adrian Hatton]

Ok that’s interesting. Thanks for the feedback 

But if there is no power applied to the VDD_CAPE pins and you connect the USB cable then it will power from USB is that how it behaves?

I don’t want the device to power from usb at all, I only want usb for connecting devices.

Sent from my iPhone

On 3 Jul 2020, at 18:39, István Gyürki <istvan...@gmail.com> wrote:



To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/CAAkqu5PVfsjNxNyXHt7cL%3DGpkznp1VUxoNR1E%2BAWjFsoOj0xHQ%40mail.gmail.com.