Electronic – arduino – How to connect one pin to ground when an another analog pin is triggered

arduinoaudiogroundsensorvoltage

I'm trying to combine two working electronics projects into one. I have a standalone piezo sensor that I can read values from when it vibrates via an arduino, and I have a standalone audio board (no arduino needed) that will play a sound file when you connect one of its pins to ground (currently via a push button).

This is the basic setup for the audio board

and this is the basic setup for the piezo / button

What I want to do is remove the need for the button to trigger sound files, and instead use the vibration from the piezo to trigger a song to play.

The sound board is set up to play a track when you connect one of its pins to ground. It has a built in pullup resistor. With the piezo, I have code executing so that, if the vibration is over a certain value, it will trigger a function to play the sound:

if (piezoV > 0.1){ //play sound }

What do I need to from a wiring & code perspective to make the piezo play the sound? What I tried was setting up one of the arduino pins to do a digital write:

const int SOUND_PIN = 2; //Trigger Sound Board
void setup() {
  pinMode(LED_PIN, OUTPUT);
  pinMode(SOUND_PIN, OUTPUT);
}

void loop() {
  int piezoADC = analogRead(PIEZO_PIN);
  float piezoV = piezoADC / 1023.0;
  if (piezoV > 0.1){
    playSound();
    delay(5000);
    stopSound();
  } 
}

void playSound(){
  digitalWrite(SOUND_PIN, HIGH);
}

void stopSound(){
  digitalWrite(SOUND_PIN, LOW);
}

Then I figured I could connect a wire from the arduino's pin 2 to the sound board's ground, and a wire from the sound board's ground to its own pin 1 (to play track 1) – but it seems like, whether there's vibration or not, when I do that the sound plays unconditionally.

WIRING:

Piezo to A0, Arduino Pin 2 to Ground, Ground to Sound FX Board Pin 1

Wiring setup to play audio with a button:

enter image description here

If anyone can point me in the right direction I'd appreciate it!

Best Answer

Can you please connect the sound board in the usual way, Arduino ground to sound board ground , Arduino pin 2 to sound board play pin 1 and modify the output for inverted logic (LOW = play and HIGH = stop set as input = stop)?

Obviously it plays all the time because the soundboard play pin is always connected to soundboard ground pin.

This is your first setup:

schematic

simulate this circuit – Schematic created using CircuitLab

First option:

schematic

simulate this circuit

Arduino uses 0-5V I/O levels , the soundboard uses 0-3.3V that's why you should use only pinMode(SOUND_PIN, INPUT); disconnecting the sound play pin instead digitalWrite(SOUND_PIN, HIGH) that pulls the pin to 5V when you want to release the pin.

To pull the pin to GND use digitalWrite(SOUND_PIN, LOW);pinMode(SOUND_PIN, OUTPUT);

See the folowing example:

const int SOUND_PIN = 2; //Trigger Sound Board
void setup() {
  pinMode(LED_PIN, OUTPUT);
  pinMode(SOUND_PIN, INPUT);// high impedance, sound pin disconnected
  digitalWrite(SOUND_PIN, LOW);//make sure the pin will be low when using it
  //this last instruction has no effect yet as long as the pin is configured as input
}

void loop() {
  int piezoADC = analogRead(PIEZO_PIN);
  float piezoV = piezoADC / 1023.0;
  if (piezoV > 0.1){
    playSound();
    delay(5000);
    stopSound();
  } 
}

void playSound(){
  digitalWrite(SOUND_PIN, LOW);//make sure the pin will be low
  pinMode(SOUND_PIN, OUTPUT);// set as output to drive the sound pin to gnd
}

void stopSound(){
  pinMode(SOUND_PIN, INPUT);// high impedance, sound pin disconnected
}

You can use the resistor R1 for the development stage to protect the soundboard input from software errors.

Other options:

Using an optocoupler as you can see in this link that I found from this similar older question. The S2 must go to Soundboard ground ans S1 to PIN 1

Using a relay, here is an example but you can find plenty on the web

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