Thanks for the suggestion, this did the trick. Even though none of the sketch code contains any Serial references, I included your while (!Serial && (millis() < 3000)); snippet at the end of the main loop. This solved the USB issue. I only had...
Yes, the regulator 5v out feeds the Vin pin, as well as the 2 multiplexers. The regulator GND and the Teensy GND are common. Both 3v3 pins show 3.29v. Everything works now, thanks to BriComp's suggestion.
Thanks for carefully describing the exact issue. Everything seems to be correct (and I note that Arduino serial monitor is not being used, so that is not the issue).
Given that the LEDs are lighting up it seems 3V3 is being generated from the 5V...
Hi everyone;
I know this issue has been discussed in a number of posts here in the past, but I still can't get my Teensy 4.1 to work with 5v external power. I've cut the trace on the back of the Teensy, which separates the USB power from the Vin...