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    M5Stack 2 Channel Oscilloscope

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    • C
      Calin
      last edited by

      The maximum voltage on ESP32 ADC can read is 3.3v
      The ESP32 don't have the voltage divider on ADC in as the DSO oscilloscope have.
      Noises can cause high voltage levels, especially near computers, where you have lots of radio waves on different frequency. So even touching the input pin (35) with your hand, the voltage at the input pin can cause more than 3.3v, especially if the ESP is connected to PC by USB cable.

      Some basic filters and voltage dividers at the input pin, can solve that problem.

      dasloloD 1 Reply Last reply Reply Quote 1
      • dasloloD
        daslolo @Calin
        last edited by

        @calin and the ESP32 can be damaged by spiked above 3.3V, I read. How do I know if I damaged mine?
        I'll add voltage divider, is there a way to remove spikes without killing the sensitivity? I am doing an FFT on the signal and don't want to smooth things out too much.

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

          If the DAC input was damaged, it won't pick up any signal that you feed to it...

          1 Reply Last reply Reply Quote 1
          • C
            Calin
            last edited by

            Btw... check out the new development: http://forum.m5stack.com/topic/165/m5stack-multiapp-firmware

            1 Reply Last reply Reply Quote 1
            • dasloloD
              daslolo
              last edited by

              If I understand this correctly, the ESP32 analog input captures only positive voltage.
              How do I get the full -/+ range in there?

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

                Make a voltage divider with 2 resistors (100k or so...) with one end connected to GND and the other end to 3.3v.
                The middle of the divider connected to oscilloscope input pin.
                Apply input signal to input pin and you get +/- 1.65v input range.
                I designed the code to be used with this divider, that's why, without the divider, the oscilloscope line is at the bottom of the screen.
                Once you connect the divider, the signal line will be at the middle of the screen just like on a normal oscilloscope.

                1 Reply Last reply Reply Quote 2
                • dasloloD
                  daslolo
                  last edited by

                  Without the voltage divider, the amplitude is the same, just offset by 1.65v?

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

                    The max amplitude is 3.3v. With the divider, the amplitude will be -1.65v to +1.65v (total 3.3v) The aplitude can be solved easy with a series of resistors at the imput. To change the input aplitude, replace the 10K resistor on the example below:
                    0_1523452685767_Vontage divider.jpg

                    P 1 Reply Last reply Reply Quote 0
                    • P
                      pkourany @Calin
                      last edited by pkourany

                      @calin 在 M5Stack 2 Channel Oscilloscope 中说:

                      he amplitude will be -0.65v to +0.65v (total 3.3v)

                      @calin, I think you meant the input signal range will be -1.65v to +1.65v (total 3.3v). :)

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

                        @pkourany 在 M5Stack 2 Channel Oscilloscope 中说:

                        @calin 在 M5Stack 2 Channel Oscilloscope 中说:

                        he amplitude will be -0.65v to +0.65v (total 3.3v)

                        @calin, I think you meant the input signal range will be -1.65v to +1.65v (total 3.3v). :)

                        yes. sorry for typo... edited now :)

                        JJJ 1 Reply Last reply Reply Quote 1
                        • JJJ
                          JJ @Calin
                          last edited by JJ

                          Awesome oscilloscope case - designed by Macsbug - infos here

                          0_1523469082882_M5Stack-OscilloscopeCase.png

                          1 Reply Last reply Reply Quote 0
                          • dasloloD
                            daslolo
                            last edited by

                            This post is deleted!
                            1 Reply Last reply Reply Quote 0
                            • ChrisWRC
                              ChrisWR
                              last edited by

                              Its restarting every 5 seconds making it useless.. what can be my problem?

                              ChrisWRC 1 Reply Last reply Reply Quote 0
                              • ChrisWRC
                                ChrisWR @ChrisWR
                                last edited by

                                @chriswr Ok solved.. disable the watchdog..

                                disableCore0WDT();
                                disableCore1WDT();

                                1 Reply Last reply Reply Quote 0
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