4. Potentiometer Monitoring

Read a potentiometer through the ESP32 ADC, convert the raw value to a percentage, and publish both values.

Level: Beginner · Time: 20 minutes

Parts and wiring

ESP32 DevKit V1 and 10 kΩ linear potentiometer

Potentiometer terminal	Connection
Outer terminal	3V3
Center wiper	GPIO 34
Other outer terminal	GND

Never power this divider from 5 V; do not exceed 3.3 V on the ADC input.

Complete sketch


#include <PxServ.h>
 
const char* WIFI_SSID = "your_wifi_ssid";
const char* WIFI_PASSWORD = "your_wifi_password";
const char* PXSERV_API_KEY = "your_pxserv_api_key";
const int POT_PIN = 34;
 
PxServ client(PXSERV_API_KEY);
 
void setup() {
  Serial.begin(115200);
  analogReadResolution(12);
  PxServ::connectWifi(WIFI_SSID, WIFI_PASSWORD);
}
 
void loop() {
  int rawValue = analogRead(POT_PIN);
  int percent = constrain(map(rawValue, 0, 4095, 0, 100), 0, 100);
 
  client.setData("potentiometer/raw", String(rawValue));
  client.setData("potentiometer/percent", String(percent));
 
  Serial.print("Raw: ");
  Serial.print(rawValue);
  Serial.print(" | Percent: ");
  Serial.println(percent);
  delay(5000);
}

Test

Turn the knob between both ends. The raw value should span roughly 0–4095 and the percentage 0–100. Swap the outer terminals if the direction is reversed. Shorter wiring and averaging can reduce unstable readings.