Power RPI by monitor USB port

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robertvg
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Joined: Mon Apr 24, 2017 2:34 pm

Power RPI by monitor USB port

Post by robertvg » Mon May 08, 2017 11:43 am

Does anybody have experience with powering the RPI by using the display USB port ?
We have displays with 1x upstream USB, and 4x downstream USB port (Fujitsu BT23-W)
I found that the downstream ports only provide power when there is a signal or power detected on the upstream port.
And once there is power on the downstream port I can remove the cable from the upstream port and the RPI will still get power from the display.

But when everything is switched off (for example in case off a general power failure), then afterwards the RPI will not get any power as the display does not detect anything on the upstream port. So the RPI will never start in that situation.

akatik
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Re: Power RPI by monitor USB port

Post by akatik » Wed May 10, 2017 8:36 am

We tested DELL P2414H. It provides power with empty upstream port.

silfermoon
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Joined: Wed Mar 16, 2016 11:46 am

Re: Power RPI by monitor USB port

Post by silfermoon » Thu May 11, 2017 5:30 pm

I have found a workaround for this. Once you connect the USB host cable to a 5v usb phone charger you will trick the monitor into thinking it is connected and will thus enable the power to the usb ports.

The good part about this construction is that your raspberry pi will now power on and off with your monitor.

robertvg
Posts: 21
Joined: Mon Apr 24, 2017 2:34 pm

Re: Power RPI by monitor USB port

Post by robertvg » Fri May 12, 2017 10:16 am

silfermoon wrote:I have found a workaround for this. Once you connect the USB host cable to a 5v usb phone charger you will trick the monitor into thinking it is connected and will thus enable the power to the usb ports.
The good part about this construction is that your raspberry pi will now power on and off with your monitor.
Can you explain this ? I don't really picture how you have connected this.
Because what I would like to achieve: power the RPI by the monitor, NO extra power adapter necessary anymore.
If possible power on/off the RPI with the monitor (but not necessary)

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