Arduino IDE2.0 with Teensy 4 question on libraries


Well-known member
Are you experts using Arduino 2.0 ?
I have been using Arduino 1.x for many years and have developed quite a few libraries.
I am always in the middle of a few projects and have not changed over to Arduion 2.0, PlatformIO or Visual Studio/Visual Micro...etc.

Any suggestions?
I have installed Arduino 2.0 and it appears that all libraries go into the sketch folder under libraries. Do I just copy my libraries from my hardware\teensy\avr\libraries into that sketch\libraries?

Am I entering a rabbits hole? (I dig enough of my own)


Thanks Paul,
I found where the libraries were stored in:

and was able to replace one (FastLED) that I had modified. I will submit my changes for inclusion in that library.
Need some help with Teensy 4.0 and Arduino 2.0

Yup, I'm in a rabbit hole.

1. Loading both Arduino 1.8.15 and Arduino 2.0 My Arduino 1.8.15 can no longer find the libraries that are in C:\Arduino\hardware\teensy\avr\libraries.

2. Running on Teensy 4.0, I can compile and run correctly, however, I see no serial output. I have to close Arduino 2.0, open a serial monitor, and I see the proper serial output. This is clearly unacceptable.

Any help? Thanks
I tried my Hello World on a Teensy 3.6 and get no serial output either (although Arduino 2.0 does compile and execute (I can see led blinking on Teensy).
Maybe some cross issue from my using TyCommander with 1.8.15?
Okay Solved Serial problem in 2.0. Small step for mouse brain.

In Tools Port There are 2 options
COM3 Serial Teensy 4.0 (selected at default installation).

The COM3 has to be selected to see Serial output.
Serial monitor at times has some issues -
I assume you clicked to open the Serial Monitor and see the windowpane at the bottom of the window, that should have your Serial output. (Same place as program builds output) but with different tab chosen.

There are times issues with the choosing the Arduino port section for the Teensy Serial port versus the Teensy part. Some of this is mentioned in a few threads including:

I have both installed. Note: 2.0.2 is in the normal place mentioned

As for 1.8.15? I as assuming you installed Arduino into the folder mentioned.
Note: there was an issue with having Arduino 2 installed that even if you built using Arduino 1.8.x it was using the files out of the Standard Arduino install location.

Paul fixed that we current releases of teensyduino (I believe by changing the boards.txt and/or platform.txt).