I've been experimenting with I2C and have been running into some issues. I have wired everything up on a breadboard and using external pullup resistors (around 4.3K). The thing is I cannot get it to communicate with another Teensy LC. After banging my head I tried communicating with an Arduino UNO instead and that worked fine (same exact wiring). The one Teensy is meant to power the other btw (as it did with the UNO). I tried both Wire and i2c_t3 libraries to no avail. i2c_t3 throws an error 4 back at me which unfortunately doesn't tell me much. Any help appreciated.