Copy in slave example code from droneworkshop

crawler_software/arduino/crawler_slave/crawler_slave/crawler_slave.ino

@@ -0,0 +1,37 @@
+/*
+  Arduino Slave for Raspberry Pi Master
+  i2c_slave_ard.ino
+  Connects to Raspberry Pi via I2C
+  
+  DroneBot Workshop 2019
+  https://dronebotworkshop.com
+*/
+
+// Include the Wire library for I2C
+#include <Wire.h>
+
+// LED on pin 13
+const int ledPin = 13; 
+
+void setup() {
+  // Join I2C bus as slave with address 8
+  Wire.begin(0x8);
+  
+  // Call receiveEvent when data received                
+  Wire.onReceive(receiveEvent);
+  
+  // Setup pin 13 as output and turn LED off
+  pinMode(ledPin, OUTPUT);
+  digitalWrite(ledPin, LOW);
+}
+
+// Function that executes whenever data is received from master
+void receiveEvent(int howMany) {
+  while (Wire.available()) { // loop through all but the last
+    char c = Wire.read(); // receive byte as a character
+    digitalWrite(ledPin, c);
+  }
+}
+void loop() {
+  delay(100);
+}