Adding Arduino I2C scan code for PiCowbell Proto.

PiCowbell_Proto/arduino_i2c_scan/arduino_i2c_scan.ino

@@ -0,0 +1,65 @@
+// SPDX-FileCopyrightText: 2021 Carter Nelson for Adafruit Industries
+// SPDX-FileCopyrightText: 2022 Kattni Rembor for Adafruit Industries
+//
+// SPDX-License-Identifier: MIT
+// --------------------------------------
+// PiCowbell Proto and Pico I2C scan code.
+//
+// Modified from https://playground.arduino.cc/Main/I2cScanner/
+// --------------------------------------
+
+#include <Wire.h>
+
+// Wire uses GPIO4 (SDA) and GPIO5 (SCL) automatically.
+#define WIRE Wire
+
+void setup() {
+  WIRE.begin();
+
+  Serial.begin(9600);
+  while (!Serial)
+     delay(10);
+  Serial.println("\nPiCowbell Proto Pico I2C Scanner");
+}
+
+
+void loop() {
+  byte error, address;
+  int nDevices;
+
+  Serial.println("Scanning...");
+
+  nDevices = 0;
+  for(address = 1; address < 127; address++ )
+  {
+    // The i2c_scanner uses the return value of
+    // the Write.endTransmission to see if
+    // a device did acknowledge the address.
+    WIRE.beginTransmission(address);
+    error = WIRE.endTransmission();
+
+    if (error == 0)
+    {
+      Serial.print("I2C device found at address 0x");
+      if (address<16)
+        Serial.print("0");
+      Serial.print(address,HEX);
+      Serial.println("  !");
+
+      nDevices++;
+    }
+    else if (error==4)
+    {
+      Serial.print("Unknown error at address 0x");
+      if (address<16)
+        Serial.print("0");
+      Serial.println(address,HEX);
+    }
+  }
+  if (nDevices == 0)
+    Serial.println("No I2C devices found\n");
+  else
+    Serial.println("done\n");
+
+  delay(5000);           // wait 5 seconds for next scan
+}