Analog voltage reading (ESP8266)


I’m trying to connect a piezo-disc to the thinger platform.

I can read the value from the disc via arduino. Now I’m on a Wemos D1 mini or D1 mini pro to use the wifi to connect to thinger.

In my arduino code I use the divider 1023 / 5 to see the voltage in the serial plotter.

I would like to see the same data on thinger.
So I tried editing the code to work on thinger. But as I thought in the following sketch (below)

    #define DEVICE_CREDENTIAL "your_device_credential"

   #define SSID "your_wifi_ssid"
  #define SSID_PASSWORD "your_wifi_ssid_password"


const int PIEZO_PIN = A0; // Piezo output

void setup() 

  thing.add_wifi(SSID, SSID_PASSWORD);
    // piezo resource
  thing["piezo"] >> outputValue(piezoV);

void loop() 
  // Read Piezo ADC value in, and convert it to a voltage
  int piezoADC = analogRead(PIEZO_PIN);
  float piezoV = piezoADC / 1023.0 * 5.0;
  Serial.println(piezoV); // Print the voltage.


The piezoV can’t be read because it doesn’t ‘exist’ yet, it only show up in the loop and i’m declaring it before the loop. As I am no real programmer, I’m wondering how to fix this and or what’s necessary to read the voltage from the piezo disc.

Any help would be very much appreciated.

Try declaring float piezoV before void setup() - making it global
and delete float in loop.
Be careful with analog input of ESP it is only 1V capable not 5V.