audioio.AudioOut – "All timers in use" on reload

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CircuitPython version

Adafruit CircuitPython 9.0.2 on Adafruit ItsyBitsy M4 board

Code/REPL

import audioio
import board
import time

time.sleep(1)

print("INIT")

audio = audioio.AudioOut(left_channel=board.A0)

print("DONE!")

Behavior

To trigger the bug, load the provided code.py code onto the board, and reload it 4 times (e.g. using Ctrl+D in Mu), letting it the code execute to completion each time. On the fourth reload, the board will fail with:

code.py output:
INIT
Traceback (most recent call last):
  File "code.py", line 9, in <module>
RuntimeError: All timers in use

It will also fail with the same error on every second reload after this.

Disconnecting and re-connecting the board resets the "counter".

Description

Seems similar to #6061 but with AudioOut instead of PWMOut?
Note: A0 pin on ItsyBitsyt M4 has a DAC, so no PWM is involved.

Additional information

No response

[dhalbert]

Note: A0 pin on ItsyBitsyt M4 has a DAC, so no PWM is involved.

We use a TC timer internally to time the DAC conversions. That timer is not being released properly, because there is no finalizer that runs when the AudioOut is gc'd. This fix would be part of #8960.

[dhalbert]

In the meantime you should be able to work around this (if it's a blocker for you), by calling .deinit() on the AudioOut when the program finishes.