🛠 Console série et lecture d'un capteur analogique

Objectives

Master serial communication on the ESP32-S2 and analog-to-digital conversion: read a potentiometer on an ADC1 channel and send the values to the serial monitor.

Hardware

• ESP32-S2 board and USB cable
• 1 potentiometer (e.g., 10 kΩ)
• 3 Dupont cables

Complete code

// Lecture ADC1 + console série sur ESP32-S2
const uint8_t CAPTEUR_PIN = 3;   // ADC1_CH0 sur la plupart des cartes S2

void setup {
  Serial.begin(115200);
  analogSetPinAttenuation(CAPTEUR_PIN, ADC_11db); // plage ~0-3,1 V
  delay(1000);
  Serial.println("Console serie ESP32-S2 prete");
}

void loop {
  uint16_t brut = analogRead(CAPTEUR_PIN);
  float tension = brut * 3.3f / 4095.0f;          // ADC 12 bits
  Serial.printf("brut=%u  tension=%.2f V\n", brut, tension);
  delay(250);
}

Expected verification

The serial monitor displays four times per second a raw value between 0 and 4095 and the corresponding voltage. Turning the potentiometer makes both values vary continuously from 0 to approximately 3.3 V.

Common errors

• Using an ADC2 pin: on ESP32 boards, ADC2 is unavailable when WiFi is active; prefer ADC1.
• Forgetting analogSetPinAttenuation: without attenuation, voltages close to 3.3 V are clipped.
• Inconsistent serial baud rate: the monitor must be set to 115200 baud.
• Confusing the two USB ports on the board (UART and native USB): if nothing is displayed, try the other port.