5 Replies Latest reply on Jun 14, 2016 12:09 AM by userc_40047

    Electret microphone to ADC

    userc_40047

      Hello everyone,

      I'm new in PSoC family.

      I am working at connecting microphone to PSoC but with no effects. I understand that I need a pre-amplifier but I wonder if it possible to use embedded software amplifier? I think about PGA or Opamp. I use them but I can't see any signal (except microphone power voltage). I use voltage divider to power the microphone.

        • 1. Re: Electret microphone to ADC
          JoMe_264151

          Welcome in the forum!

             

          Audio microphone output is +- AC, PSoCs only accept signals between GND and VDDA, so you will need to do a level-shift with an R-ladder. Yes, you may use the internal (hardware, not software) OpAmp or PGA. Signal restrictions apply to both of them too.

             

          When still stuck,  you may post your complete project (plus some schematic), so that we all can have a look at all of your settings. To do so, use
          Creator->File->Create Workspace Bundle (minimal)
          and attach the resulting file.

             

           

             

          Bob

          • 2. Re: Electret microphone to ADC
            userc_40047

            Thanks for quick reply,

            I attached the project and microphone specs. 

               

            • 3. Re: Electret microphone to ADC
              JoMe_264151

              The transfer function for your PGA is

                 

              Vout = Vref + (Vin – Vref) × Gain

                 

              Vin is in the range of +- a few mV, but your Vref lies at some V.  You need to shift the Vin a few mV above GND and you may take internal Vss as Vref thus saving a pin

                 

               

                 

              Bob

              1 of 1 people found this helpful
              • 4. Re: Electret microphone to ADC
                BoTa_264741

                Amplify only AC component coming from microphone. As an example, see attached picture

                • 5. Re: Electret microphone to ADC
                  userc_40047

                  Hi all,

                  I have to rebuild my project and now I have to problems to solve.

                  First - i use "Music Creation" project on CY8CKIT-033A. I have to connect stereo microphones (with parameters in earlier post) to line-in and record sounds using iPhone. With resistor, capacitor and VCC (3.3V) I can see something in records but it is too quiet. Can I gain this sound internally in PSoC or I must use external components (op-amp)? I tried to add PGA after op-amp but with it there is no sound.

                  Second - I have MEMS microphone with 0.66V dc and +/-100mV sound - I can't read it properly. Hot to cut-off this 0.66V and gain this 100mV to get wider and more accuracy measurement? I need to use this microphone to phone calls.