The first servo

// The first servo: channel 0 between 1000 and 2000 us.
//
// Wiring      ESP32-S3 DevKitC    Arduino Uno
//   GND ->    GND                 GND
//   VCC ->    3V3                 5V
//   SDA ->    GPIO 8              A4
//   SCL ->    GPIO 9              A5
//   OE, V+    not connected       not connected
// A 5 V USB-C adapter in the board's USB-C socket.
// Servo on channel 0, brown or black wire on the GND row.
//
// Arduino IDE: Tools > Board > ESP32S3 Dev Module,
//   or Arduino Uno.
// ESP32-S3: Tools > USB CDC On Boot > Enabled.
// Serial Monitor at 115200.
// Library: Adafruit PWM Servo Driver Library.

#include <Wire.h>
#include <Adafruit_PWMServoDriver.h>

// 25 MHz is the datasheet's typical figure, not a
// promise. Adafruit's servo example assumes 27 MHz.
// Measure yours: osc = Hz x 4096 x (prescale + 1).
const uint32_t OSC_HZ = 25000000;

const uint8_t CHANNEL = 0;
const uint16_t END_A = 1000;    // us
const uint16_t END_B = 2000;    // us

Adafruit_PWMServoDriver pwm = Adafruit_PWMServoDriver(0x40);

void moveTo(uint16_t us) {
  pwm.writeMicroseconds(CHANNEL, us);
  Serial.print(us);
  Serial.println(" us");
}

void setup() {
  Serial.begin(115200);
  delay(1000);

#if defined(ESP32)
  Wire.begin(8, 9);             // SDA, SCL
#else
  Wire.begin();                 // A4, A5 on an Uno
#endif

  if (!pwm.begin()) {
    Serial.println("No PCA9685 at 0x40.");
    Serial.println("Check GND, VCC, SDA and SCL.");
    while (true) delay(1000);
  }
  pwm.setOscillatorFrequency(OSC_HZ);
  pwm.setPWMFreq(50);           // one pulse every 20 ms
  Serial.println("PCA9685 at 0x40, 50 Hz");
}

void loop() {
  moveTo(END_A);
  delay(1500);
  moveTo(END_B);
  delay(1500);
}