In this simple tutorial I will explain how to connect and use the ISD1820 module using the NodeMCU board.
P.S. sorry for my bad English.

Reading the module datasheet it is written that :This module use is very easy which you could direct control by push button on board or by Microcontroller such as Arduino, STM32, ChipKit etc.
From these you can easy control record , playback and repeat and so on.

Step 1: What Do You Need ?!

To realize this project we need :
NodeMCU board.

ISD1820 module.

Breadboard speaker (it is usually included with the module).

Remember : the NodeMcu board works at 3.3 volt so to connect with the module we do not need resistors in the circuit since the module also works at 3.3 volt.

Step 2: Connections

It is very easy to connect the NodeMcu board with the module, we need only 5 wires.
Make the connection as shown in the picture or as shown in the video. Remember that when programming the nodeMCU the names differ from those in the Arduino IDE and then I recommend you in testing phases to run the connections as shown and load the program shared.

Step 3: the Code

The ISD1820 module is controlled by 3 pins, each pin if it receives (so the module pins are input) a 3.3 volt signal will make the module perform a different function (obviously depending on the pin to which the signal is sent).
As shown in the drawing, the ISD1820 is equipped with 3 modes of use, each mode selectable with a signal of 3.3 volts sent from the nodeMcu. The modes are "recording" where a sound is recorded by the microphone welded to the module (it has a very short maximum recording time), the mode of "reproduction" of the previously recorded sound and finally the mode of "reproduction in part of the sound" where the sound is reproduced in part, under certain conditions that during programming I will explain

. Looking at the design I made (I don't know how to draw lol) you can easily guess how the board works where the red arrows represent a signal of 3.3 volts sent from the nodeMcu to a single pin of the module. (The black arrows represent that no signal is sent so we will write "LOW" to the pins in the program)

After understanding the functioning of the circuit we can start writing the program. As already mentioned to program the NodeMCU we will use the Arduino IDE. The program is very simple: after declaring the 3 pins (indicating the 3 modes) and setting them as output pins we can start writing our functions.(I use the serial monitor only to send from the keyboard the command to activate a certain function of the module).

The first function is "record" where if the 'REC' pin is high the module will start recording that sound for as long as the pin is high.

The second function "playSignal" where you just have to send a short signal to the module to activate the playback of the recorded sound (pin PLAY_E).

The last function is "playSignal_L" where the module will play the sound only for the time that the pin ' PLAY_L' is high (for example if the recorded sound is 3 seconds and I activate the function playSignal_L only for one second the module will play that sound only for one second)

After writing the program, load it on the NodeMCU and have fun playing with the circuit. I hope I have helped you. Robogi