first commit Arduino version of step switch pico demo

Step_Switch_Pico_Demo_Arduino/Step_Switch_Pico_Demo_Arduino.ino

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+// SPDX-FileCopyrightText: 2022 John Park for Adafruit Industries
+// SPDX-License-Identifier: MIT
+// Step Switch Party for Pico
+
+// extra library used:
+// Bounce2 -- https://github.com/thomasfredericks/Bounce2
+
+#include <Wire.h>
+#include <Bounce2.h>
+
+
+const int num_buttons = 4;
+const int led_pins[num_buttons] = {2, 3, 4, 5};
+const int button_pins[num_buttons] = {6, 7, 8, 9}; 
+Bounce buttons[num_buttons];
+bool led_vals[num_buttons];
+
+
+void setup() {
+  Serial.begin(9600);
+  delay(1000);
+  Serial.println("Step Switch Pico Party");
+
+  for (uint8_t i=0; i< num_buttons; i++){
+    buttons[i].attach( button_pins[i], INPUT_PULLUP);
+  }
+
+  for (uint8_t i=0; i< num_buttons; i++){
+      pinMode(led_pins[i], OUTPUT);
+      digitalWrite(led_pins[i], HIGH);
+      led_vals[i] = HIGH;
+  }
+}
+
+
+void loop() {
+  for (uint8_t i=0; i< num_buttons; i++){
+    buttons[i].update();
+    if( buttons[i].fell()) {
+      // do something here, such as send MIDI, change a NeoPixel animation, etc.
+      Serial.println(i);
+      led_vals[i] = !led_vals[i];
+      digitalWrite(led_pins[i], led_vals[i]);
+    }
+  }
+  
+}