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A4 and USB with USB power supply
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A4 and USB with USB power supply

by TDMAudioPro on Mon Jun 15, 2020 4:09 pm

Hi !

I'm making a little circuit with a Trinket 5V.

The goal is to measure 2 UV sensor and light up 2 LED if there is any UVC present on the sensors.

I use A1 (PB2) for the sensor and PB0 for the LED and it works great.

And for the second sensor, I use A4 (PB4) and it only work when I power the Trinket with a USB from a computer. It doesn't work if I use a USB power supply ...

I know A4 (PB4) is a shared pins with the USB but what can I do to make it works with a simple USB power supply ?

Thanks for your help !

TDMAudioPro
 
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Joined: Mon Jun 15, 2020 3:59 pm

Re: A4 and USB with USB power supply

by adafruit_support_bill on Mon Jun 15, 2020 4:37 pm

Most USB Power supplies have resistor networks attached to the data pins. This is to signal to the attached device what the charging capabilities are. Different manufacturers have different 'standards' for how to do this:

https://curioussystem.com/2010/08/18/th ... -charging/

You could try using a cable with the data pins disconnected.

adafruit_support_bill
 
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Joined: Sat Feb 07, 2009 10:11 am

Re: A4 and USB with USB power supply

by TDMAudioPro on Mon Jun 15, 2020 4:41 pm

Great ! Thanks a lot!

I'll try tomorrow and let you know !

TDMAudioPro
 
Posts: 2
Joined: Mon Jun 15, 2020 3:59 pm

Please be positive and constructive with your questions and comments.