USB Micro pin 4?

[MuShoo]

In looking at the Teensy 3.0/3.1 schematic, I'm a bit confused as to what to do with pin 4 from the USB Micro connector. I'm integrating a Teensy onto a board, with a built in USB hub (so I won't actually be using a USB connector direct to the MK20/MINI54, it'll be a downstream device on a Cypress hub IC). Should pin 4 be left floating? So Mini54 P0.0 connects only to MK20 PTA1, and not to the USB chain at all? Or should it be connected to ground? (Ground supposedly would identify it as a 'host,' though I'm not sure how that applies here...)

Thanks!

 

[PaulStoffregen]

Should pin 4 be left floating?

Yes, leave it floating (no connection to that Cypress HUB chip), but do make the connection from Mini54 P0.0 to MK20 PTA1.

 

[MuShoo]

Great, thanks Paul!

 

[Constantin]

I have a dumb question - what would happen if I accidentally grounded pin 4 on a home-made board? Would it disable the USB connections for the Mini54 and MK20?

 

[PaulStoffregen]

what would happen if I accidentally grounded pin 4 on a home-made board?

With today's software, it should have no effect. That pin is ignored.

Future versions (in the very distant future) might do something with that pin.