#include <Arduino.h>

#define SERVO_PIN 0  //  PB1 = pin 1
#define MIN_PULSE 500  // 0° pulse width (µs)
#define MAX_PULSE 2500 // 180° pulse width (µs)
#define SERVO_PERIOD 20000 // Servo signal period (20ms)

void setServoAngle(uint8_t angle) {
  uint16_t pulseWidth = map(angle, 0, 180, MIN_PULSE, MAX_PULSE);
  digitalWrite(SERVO_PIN, HIGH);
  delayMicroseconds(pulseWidth);
  digitalWrite(SERVO_PIN, LOW);
  delayMicroseconds(SERVO_PERIOD - pulseWidth);
}

void setup() {
  pinMode(SERVO_PIN, OUTPUT);
  setServoAngle(0);
  delay(1000);
}

const int sweep_speed = 15;
void loop() {
  // Sweep from 0° to 180°
  for (int angle = 0; angle <= 180; angle++) {
    setServoAngle(angle);
    delay(sweep_speed);
  }
  // Sweep back to 0°
  for (int angle = 180; angle >= 0; angle--) {
    setServoAngle(angle);
    delay(sweep_speed);
  }
}