CraigH

That's terrific. This works perfectly thank you! The behaviour with the AudioOutputI2S object is still a bit odd, but I can certainly live with the result using startup_late_hook. (And I have now read about the 3 hooks for future reference.)

Another thought. I actually only need to read the temperature (pin 22) once before the starting the audio system. (The sensor is used for pitch adjustments, as the unit will be playing along with organ pipes, which change pitch with temperature.)...

Thanks. The serial monitor displays pretty much confirm what I am seeing. Having established that Pin 22 is most likely receiving some on-chip noise, I've gone back to the original scenario I was debugging. The original case was a TMP36 3 pin...

I'm sure the resistors are fine, because if I comment out the AudioOutputI2S, both inputs read correctly. The 6mV issue, I agree is probably noise for the neighbouring pins. I put a CRO on Pin 22 and it's a weak waveform resembling the neighbours...

I've simplified it down to the most basic hardware and code. I've attached a picture of the hardware I'm using and a screenshot of the code and monitor window.

I believe there is still a code problem with analog reading on Teensy4.1 Pin 22 when the AudioOutputI2S object is present. The quick standalone test I did at an earlier post showed that inputs were varying with analogRead(22) as the input voltage...

Actually I've not connected Pin 22 to the shield, so it's not that, but it must be something similar. I think the ball is in my court again. Thanks.

Ok thanks. I therefore tried it on a standalone T4.1 without shield or other hardware, and yes it works as expected. Must be a hardware thing which I'll look into.

I'm using the Teensy 4 Rev D audio card with a Teensy4.1. The audio works well, however when I define the audio output object as AudioOutputI2S, this disables analogRead(22). As far as I can see from the RevD schematic and the pin descriptions...