Mood dial on an Arduino Uno

// Mood dial: turn a potentiometer and a servo points to match.
//
//   potentiometer   one end -> 5V, the other end -> GND, middle (wiper) -> A0
//   servo           brown -> GND, red -> 5V, orange -> pin 9
//
// The knob is a voltage divider: the wiper slides from 0 V to 5 V, and A0
// reads that as 0 to 1023. map() stretches 0..1023 onto the servo's 0..179
// degrees, and the horn follows the knob. Tape an arrow to the horn and a
// card of faces behind it, and it tells people how your day is going.
//
// A real servo jolts the 5 V line every time it starts to move. A 100 uF
// capacitor across the supply near the servo, as the kit book suggests, keeps
// that jolt from wobbling the knob's reading.

#include <Servo.h>

Servo pointer;
int lastAngle = -1;

void setup() {
  pointer.attach(9);
  Serial.begin(9600);
  Serial.println("Mokxi Uno: mood dial");
}

void loop() {
  int knob = analogRead(A0);
  int angle = map(knob, 0, 1023, 0, 179);
  pointer.write(angle);
  if (angle != lastAngle) {
    lastAngle = angle;
    Serial.print("knob ");
    Serial.print(knob);
    Serial.print(", angle ");
    Serial.println(angle);
  }
  delay(15);
}