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    Noise on speaker

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    • reaper7R
      reaper7
      last edited by reaper7

      Yes, I hear white noise (I have to put my ear to be heard) + and second one, annoying, audible from a distance.
      I have too M5Stack limited edition

      MY GITHUB: https://github.com/reaper7/

      1 Reply Last reply Reply Quote 0
      • D
        deshipu
        last edited by

        I also noticed a lot of noise on the speaker, and I can tell that a large part of it comes from the SPI signal going to the display, from the PWM on the display backlight, from the signal on the UART from uploading, and pretty much from every single thing the module does. The reason for this is probably that the audio lines are not designed and shielded properly, and all sort of electrical activity in the module affects the audio signal.

        I noticed that moving the speaker leads under the PCB affects the intensity of the noise in different situations (probably depends on which part it is closer to).

        This is exceptionally poor design, I'm afraid.

        on4aaO 1 Reply Last reply Reply Quote 1
        • on4aaO
          on4aa @deshipu
          last edited by

          @deshipu This is for those who can live without audio and want to safe on power consumption along the way.

          Note that the audio amplifier can be disabled by placing a solder bridge over the two correspondingly marked PCB pads next to the ESP32.

          Serge — http://hamwaves.com/iot/

          1 Reply Last reply Reply Quote 0
          • JJJ
            JJ
            last edited by JJ

            @on4aa Hi Serge,

            I haven't had any significant ongoing problem with this....

            Regardless, just to clarify for those playing along at home, I take it this is where you suggest the solder bridge - (Edit: photo deleted as it ultimately did not aid the discussion and added unnecessary additional screen scrolling - JimiT.)

            1 Reply Last reply Reply Quote 0
            • on4aaO
              on4aa
              last edited by on4aa

              No, I am talking rather about this optional solder bridge marked with AMP on the PCB:

              optional AMP solder bridge

              Serge — http://hamwaves.com/iot/

              1 Reply Last reply Reply Quote 2
              • on4aaO
                on4aa
                last edited by on4aa

                With respect to the noise, I hear the following:

                1. Interference or capacitor noise on every instance when something on the screen is being drawn,
                2. A very brief high-pitched squeak when the device is connected through USB and the cable temporarily makes a bad contact when being manipulated.

                There is little that can be done about the first source apart from redesigning the PCB and perhaps replacing certain capacitors with more expensive tantalum variants.

                As for the second source, I am wondering if we are dealing here with an undocumented audible brown out (i.e. undervoltage) warning. I am using the optional 850mAh battery and I charged my device well before use. By consequence, I do not hear it that often, only when manipulating the USB cable when connected.

                However, those using the bottom plate battery of a mere 150mAh battery, perhaps without properly charging it, might here the high tone more often or even continuously.

                I am hoping more users and certainly the designers will chime in here (pun intended) to clarify this situation.

                Serge — http://hamwaves.com/iot/

                1 Reply Last reply Reply Quote 2
                • on4aaO
                  on4aa
                  last edited by

                  Here is how the audio amplifier can be disabled:
                  AMP power schematic

                  Serge — http://hamwaves.com/iot/

                  1 Reply Last reply Reply Quote 1
                  • T
                    techcntrl
                    last edited by techcntrl

                    Hi,

                    If someone still have the issue these two lines should solve the problem

                    ledcDetachPin(SPEAKER_PIN);
                    pinMode(SPEAKER_PIN, INPUT);

                    C 1 Reply Last reply Reply Quote 0
                    • C
                      Calin @techcntrl
                      last edited by

                      The solution is much easyer:

                      dacWrite (25,0);

                      L 1 Reply Last reply Reply Quote 3
                      • L
                        Leo05 @Calin
                        last edited by

                        @calin Thanks!
                        Precision: dacWrite (25,0); must be in the void loop

                        1 Reply Last reply Reply Quote 0
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