@felmue Thanks! So then I can add an external speaker or stick a wire on it and use that as the antenna of an AM transmitter ;)
like in this video: https://www.youtube.com/watch?v=lRXHd3HNzEo

Using UIFlow, I don't get the DAC to produce an audible sine wave on the internal speaker. What am I doing wrong? The speaker is not broken, it can play a wav file.

0. Initialization
1. I play a wav file from internal flash to confirm that the speaker is working.
2. I initialize the Dac 0 to port 25. This should be connected to the speaker
3. I start a sine wave on the DAC with a duration of 0, that should be infinite.
4. A loop with some code to read and display the ToF sensor.
5. The code to modify the frequency is omitted. I just want it to play 440 Hz for to sort out this problem. The loop code displays the sensor output changes, no problem there.

I want to make a Theremin using 2 ToF sensors, the DAC and the internal speaker. PbHub is not working either but there is a bug report elsewhere for that.
I also noticed I cannot set the speaker volume for the WAV? How to do that?
Is that the problem?
See screenshot below:

I have the same problem with the PaHub and two ToF sensors.
Firmware Used: v1.7.2-core2

Simple code to reproduce below. And Screenshot for graphical representation.

from m5stack import *
from m5stack_ui import *
from uiflow import *
import unit

screen = M5Screen()
screen.clean_screen()
screen.set_screen_bg_color(0xFFFFFF)
pahub0 = unit.get(unit.PAHUB, unit.PORTA)
tof0 = unit.get(unit.TOF, unit.PAHUB0)
tof1 = unit.get(unit.TOF, unit.PAHUB1)

label0 = M5Label('Text', x=21, y=13, color=0x000, font=FONT_MONT_46, parent=None)
label1 = M5Label('Text', x=21, y=71, color=0x000, font=FONT_MONT_46, parent=None)


while True:
  label0.set_text(str(tof0.distance))
  label1.set_text(str(tof1.distance))
  wait_ms(2)

From what I understand the Core bases do not fit to the newer Core2 Module.
Create more Core2 Modules

Having Theremin radio antenna with a Groove connector using i2c would be awesome.

I am currently trying to building a "Theremin" using ToF sensors. That will probably work but is not the real thing.