Teensy 4.0,4.1 web pages need a warning about INPUT_DISABLE on Analog Inputs

[Nixiebunny]

The Teensy 4.0 and 4.1 analog inputs require the digital inputs to be disabled, otherwise they have a weak pullup/pulldown circuit active that causes a small glitch around the midpoint, ~1.67V.
The cure is this statement in the setup() section:
pinMode(<pin>, INPUT_DISABLE);

The Teensy 4.0 and Teensy 4.1 product pages, in the Analog Input section, need to state this important fact.

I wasted a couple hours before I finally figured out the right Google search terms to find the forum discussion in which this is revealed.

[MarkT]

I think its the bus-keeper functionality, and there is somewhere a thread about this.

Note the description on the product page:

Digital Input Pins
Digital pins may be used to receive signals. Teensy 4.0 pins default to INPUT most with a "keeper" resistor. Teensy 4.0 pins accept 0 to 3.3V signals. The pins are not 5V tolerant. Do not drive any digital pin higher than 3.3V.

This issue could be regarded as simply a bug in analogRead() for the T4. The T4 is the most recent Teensy so there are still issues like this.

[ here's that thread: https://forum.pjrc.com/threads/34319...+INPUT_DISABLE ]