using VUSB pin with stacked teensy + audio adapter board?

[frankfurter]

hi!
wasn't sure exactly where to post this

but basically i am using a teensy 4 with the audio adapter board
& building a PCB around them
and i just realized theres no thru hole pad for the VUSB on the audio adapter itself
it gets a lil tricky if u want to stack the two boards on top of each other with a pair of male headers
as theres no physical place for the pin to go in this situation

i've got a few ideas on how to work around this
but each has its flaws

wondering what others have done in this situation?
am i missing something obvious?

also maybe a friendly suggestion of making the audio adapter boards with the thru hole pad for the VUSB on it?
i know its not that simple in the grand scheme of things
would be nice simple flexible and elegant this way
theres even a fairly open space on the PCB right where it would be

thanks!

 

[KenHahn]

One option would be to put the Teensy 4.0 on the bottom. In that case you lose easy access to the program button, but if you are doing a PCB a remote button can be mounted and connected to the Program pin on the end of the module.

 

[frankfurter]

hey thanks for the reply!

yea i think thats what i'm gunna end up doing
dont love having to cut the top of the pin to make it fit every time
or having the reset button covered
but this seemed to be the least amount of pain of all the options i thought of // found

i could also put the teensy on top and place the VUSB pad to the side or something
then run a lil wire between the two
but that kinda defeats the purpose of socketing it

what about removing the need for the VUSB pin altogether?

so far i've seen a simple diode setup
a fancy chip solution
and a transistor switch kinda thing
seems to still get a lil hairy in their own ways tho

 

[KenHahn]

It depends on what you are trying to accomplish.

The VUSB pin is mainly handy for if you want to just cut the VUSB/5V trace and bring the VUSB power down to the baseboard where you can put a diode between the VUSB power and Teensy 5V pins. A second diode is then added between the 5V power and 5V pin of the Teensy. The two diodes with both cathodes pointing to the Teensy 5V pin ensure that the USB and 5V power supply don’t try to back feed each other if you connect both at once.

If you don’t mind soldering a small SMD diode across the pads under the Teensy, then you generally don’t need to bring the VUSB pin down. After you cut the trace, the diode connects the USB power to the 5V pin on the Teensy. You still need the other diode on your baseboard for the 5V input that is feeding the Teensy 5V pin.

Your 5V at the Teensy will be about 4.6V if using Schottky diodes. If you need access to the full 5V from USB, then you are again needing to use the VUSB pin to tap into that 5V power before the diode.