add week 9

content/docs/2023/code-design/9/examples/tone_minimal/tone_minimal.ino

@@ -0,0 +1,17 @@
+const int button_pin = 2;
+const int sound_pin = 9;
+
+void setup() {
+  pinMode(button_pin, INPUT);
+  //tone()を使うときは3,11以外
+  pinMode(sound_pin, OUTPUT);
+}
+
+void loop() {
+  if (digitalRead(2) == HIGH) {
+    tone(sound_pin, 1000);
+  } else {
+    noTone(sound_pin);
+  }
+  delay(20);
+}