Question on Powering the PyPortal

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cookingissues
 
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Question on Powering the PyPortal

Post by cookingissues »

I hope this is the right place for this question. I'm building the Pyportal into a device that I wish to power via a usb port (power only, no data) from the back but I would like to maintain the usb port up front for connecting to the PC. I am going to cut the 5 volt jumper on the I2C and JST connectors to switch them over to 3.3V. Can I just apply 5 volts from the rear usb power jack to the unused 5 volt pad on the jumper section? If I do that, what will happen if I plug the Pyportal into my PC when there is power on the rear USB jack? I can't tell if there is any sort of protection against bad things happening.
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Dave

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adafruit_support_mike
 
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Re: Question on Powering the PyPortal

Post by adafruit_support_mike »

I'm not sure I understand what you want to do.

The PyPortal only has one USB jack, so there's no option to use a 'front' and 'back' USB connection.

If you want to use a secondary power source while keeping the USB jack free for programming, it would probably be best to use the D3 or D4 JST jacks. Those have VCC and GND connections, and you can ignore the analog input line.

It would be a good idea to run power to the VCC pin through a Schottky diode. Using a diode will let the onboard 3.3V regulator take over any time you plug in a USB cable for programming, and will let the secondary power source take over any time you unplug the USB cable. Using a Schottky diode will reduce the amount of voltage you lose through the diode.

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