The Teensy 4.0 operates at 3.3V internally and expects I/O to not exceed 3.3V. It is not 5V tolerate on any of its pins except for the VIN and VSUB pins which can be used to supply 5V power to the module. If you use any 5V peripherals that drive signals back to the Teensy 4.0, be sure to utilize logic level shifters to avoid possible damage.What does " 5V tolerance " mean on Teensy 3.2?
I can tell you 5V tolerance is about inputs. That means you can connect some other device that sends a 5V signal to Teensy 3.2. Even though the chip is 3.3V, it will not be damaged if you connect a 5V signal to the digital pins. When the digital pins are used as outputs, they drive 3.3V output when high.What kind of signal does Teensy 3.5 have?
The Teensy 3.5 operates at 3.3V internally and when driving digital outputs will output a 3.3V signal. This is typically fine for most 5V peripheral devices to detect a logic HIGH level. Digital input levels coming from 5V peripherals will not damage the chip.Where is the led on the teensy 4.0?
The Teensy 4.0 has the on-board LED attached to pin 13 like a typical Arduino. If the setup is correct, the software will compile and download to the Teensy. The onboard LED should start blinking once per second.