AudioOutputI2S on Teensy 4.0 not working? Hair puller!

[beermat]

Ok, went to simplest possible setup - Guitar example from the Audio library, taking TX, LRCLK and BCLK to Adafruit I2S 3W Class D Amplifier Breakout - MAX98357A.

AudioOutputI2S works on T3.6 with DIN=22, LRCLK=23, BCLK=9, I hear the guitar

AudioOutputI2S does NOT work on T4.0 with DIN=7, LRCLK=20, BCLK=21, silence

However, if I change the sketch on T4.0 to AudioOutputI2S2 and connect DIN=2, LRCLK=3, BCLK=4, I hear the guitar again

It's just 3 pins and I've checked and rechecked and redone. I saw a thread here from October 2019 that had the same issue and the final post was effectively "Turns out to be a well documented PC/USB issue, not Audio library, reinstalled stable Teensyduino 1.48 and all good"

Can't find that "well documented" issue; tried this with Teensyduino 1.50 and 1.51, IDE 1.8.11. Help appreciated!

 

[wcalvert]

The primary I2S interface is definitely working for many of us, across many Teensyduino versions as well.

Can you post the code you are using?

 

[PaulStoffregen]

The rev D audio shield uses those pins. It definitely does work.

 

[PaulStoffregen]

I purchased a MAX98357 breakout board. I'm listening to it right now, with the Synth > Guitar example (no edits, not even removing the SGTL5000 stuff).

It's quite loud, definitely working!