Page 1 of 1

USB-BUB logic level

Posted: Mon Sep 16, 2013 9:54 am
by BobW2
Is it OK to set the Logic Level on the USB-BUB-I to 3.3v when uploading to a BBB (optiboot) powered at 5V ?

I have always set the logic level of my USB-BUB at 5v, but accidentally left it at 3.3v prior to uploading today.
The upload went fine.

Would it therefore be OK to permanently connect the Logic Level jumper to 3.3v ?
Then, would I be able to program BBBs or RBBBs running at either 3.3v or 5v, without fussing with the pin header jumper.

Thank you.


PS - reason this came up was that I had the jumper set at 5v and connected it to a TP-Link 703n, which runs at 3.3v, and this seems to have killed it. This wouldn't have happened if USB-BUB was hardwired to 3.3v.

Re: USB-BUB logic level

Posted: Tue Sep 17, 2013 9:41 am
by paul

Not only is it fine to set the logic level to 3.3Vs on both BUBs, it is the default setting on the BUB2 that comes with the solder jumpers set to that level.

The reason, as you have found out, is that it is more universal. 5 volt boards still see 3.3volts as logic high.


Re: USB-BUB logic level

Posted: Tue Sep 17, 2013 11:34 am
by BobW2
Thank you Paul !