I'm trying to use an ISD1820 recording module with the ESP32, except I want to store the recordings and send them over Wifi rather than playing them back. The ISD1820 has an output for an 8-ohm speaker, which can be used in feedthrough mode (meaning the mic input goes directly to the output). I want to connect the 8-ohm speaker output to the ESP32 analog input, then store the recordings. How can I do that?

Please don't mention any other chips or modules. (e.g. saying "just buy a sparkfun recording module, etc.)


  • why are you using the ISD1820?
    – jsotola
    Commented Mar 3 at 21:10
  • You probably need to offset the voltage to 1.65V (half of 3.3V) to accommodate the symmetric speaker output (using a voltage divider between 0V and 3.3V would be the easiest). Also you need to make sure, that the voltage stays in the range between 0V and 3.3V, so that it doesn't destroy the ESP (maybe by using a Zener diode?). So probably possible, though this being not a good choice of chip for it.
    – chrisl
    Commented Mar 3 at 22:38

1 Answer 1


Connect the output of the ISD1820 (which is connected to the 8-ohm speaker) to one of the analog input pins of the ESP32.Set up the ESP32's analog-to-digital converter (ADC) to sample the audio input from the ISD1820. Write code on the ESP32 to continuously sample the audio input from the ISD1820 using the ADC. You'll need to buffer the audio samples in memory to store them temporarily before transmission. Here is a tutorial that you may find useful:https://www.instructables.com/NodeMcu-Speak-With-ISD1820-Module/

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