Turn off VDD_5V or SYS_5V

[Denis Cosmin]

Hello, is it possible to turn off the VDD_5V pin or the SYS_5V pin?

[evilwulfie]

Why would you want to do that ?

On 12/26/2016 5:03 PM, Denis Cosmin wrote:

Hello, is it possible to turn off the VDD_5V pin or the SYS_5V pin?

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[Denis Cosmin]

I wanted to power an Arduino and I didn't want to use a relay.

[lorriane...@yahoo.com]

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On Tue, 12/27/16, Denis Cosmin <denis...@gmail.com> wrote:

Subject: Re: [beagleboard] Turn off VDD_5V or SYS_5V
To: "BeagleBoard" <beagl...@googlegroups.com>
Date: Tuesday, December 27, 2016, 2:19 AM

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data unirea deplin recunoscuta chiar daca numai pe durata domniei si vietii lui Cuza eforturile sale s-au indreptat spre infaptuirea marelui program de reforme care va edifica'Romania moderna. Dar luptatorii de la 1848 se vor gasi acum pe pozitii diferite.

[Gerald Coley]

Yes, you can turn those off by unplugging the power supply.

Gerald

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Gerald

 

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[William Hermans]

On Mon, Dec 26, 2016 at 5:19 PM, Denis Cosmin <denis...@gmail.com> wrote:

I wanted to power an Arduino and I didn't want to use a relay.

Technically speaking, what you're asking I do think is possible. When using a battery, the beaglebone will still continue running after the 5VDC input is removed. However, since the battery is only 3.7v nominal. you'll no longer have a 5volt rail to power the USB. That's at minimum. I'm not sure whatever other effects you'll encounter here, but the beaglebone will continue to run until shutdown, or ( not recommended ) the battery runs out of usable power.

Anyway, do keep in mind I'm no electronics engineer. Gerald definitely is( just posted a comment to this post, s I write mine. ), and I'm pretty sure Wulfman is too.

What I've done personally is powered an MSP430 V1.5 Launchpad from the 3v3 power on the P9 header. Why I did this was so that I had the external MCU powered after the beaglebone is up, and hopefully the pins I had connected back to the P8/P9 headers of the beaglebone already had power. That is to keep form having to isolate input/output pins to, or from the beaglebone. To help mitigate burning out the pins, or worse yet the AM335x processor on the beaglebone.

With all that said, I think it would be prudent to use some sort of "switch" to power your external board. This, if done correctly would make absolutely sure the pins on the Arduino would not be active before the pins on the beaglebone. Assuming you are connecting pins between the two. In addition to that, I'm not quite sure if it would also be prudent to isolate the pins connected between the two boards. But if I/O on the Arduino is 5V, you'll definitely want to buffer or level convert for sure. Asthe GPIO pins on the beaglebone are 3v3 tolerant only, while the ADC pins on the beaglebone are 1.8v tolerant.

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