I've read through all the posts I could find but I'm still not clear. When powering a Teensy 3.1 with external 3.3v, do I only need to connect it to one of the 3.3v pins, or should I connect to all of them? What about the 3.3vout pin?
Correct. Connect your External PSU to 3.3v (Red Circle) and External PSU GND to the teensy GNG (Black Circle), you will also want to cut the VUSB jumper (Yellow Square). So that way you don't try and use the onboard Regulater to power your external powersupply.
