Fix a bug where arduino would crash on incorrectly sized i2c payload

README.md

@@ -0,0 +1,7 @@
+# To install on robot
+
+```
+git clone <url>
+cd lewis-crawler/crawler_software/raspberry_pi
+make install?
+```

crawler_software/arduino/crawler_slave/crawler_slave.ino

@@ -10,27 +10,28 @@
 // This servo is used to wipe and clean the camera lens
 Servo windowWiperServo;
 
-// This is a variable capable of storing up to 4 items
-char instruction[32] = "";
-
-// Values for the id, and raw value of an instruction
-char * id;
-char * raw_value;
+// Variables populated over i2c from master
+int id;
+int val;
 
 void setup() {
+  // For debugging
+  //Serial.begin(115200);
+  
   // Attach the wiper servo to pin 9
   windowWiperServo.attach(9);
 
-  // This is only useful for debugging
-  //Serial.begin(9600);
-
   // This is the address the pi will speak to us at
   Wire.begin(0x4);
   
   // Call receiveEvent when data received                
   Wire.onReceive(receiveEvent);
 
-  //Serial.println("Finished Setup.");  
+  // Setup LED
+  pinMode(LED_BUILTIN, OUTPUT);
+  digitalWrite(LED_BUILTIN, LOW);
+
+  //Serial.println("Started");
 }
 
 // Just loop to keep the running code alive, and wait for events to happen.
@@ -40,27 +41,23 @@ void loop() {
 
 // This method runs when we receive a message
 void receiveEvent(int n) {
+  Wire.read(); // Remove smbus trash
+  if (true) { // Dont do anything if this is not true
+    id  = Wire.read(); // ID of the servo/device to access
+    val = Wire.read(); // Value to assign
 
-  for (int i = 0; i < n; i++) {
-    instruction[i] = Wire.read();
-    instruction[i + 1] = '\0'; //add null after ea. char
+    //Serial.println(id);
+    //Serial.println(val);
+  
+    switch(id) {
+      case 1:
+        windowWiperServo.write(val);
+        break;
+    }
   }
 
-  //RPi first byte is cmd byte so shift everything to the left 1 pos so temp contains our string
-  for (int i = 0; i < n; ++i)
-    instruction[i] = instruction[i + 1];
-
-  id = strtok (instruction, "-");
-  raw_value = strtok (NULL, "-");
-
-  int value = atoi(raw_value);
-
-  //Serial.println(id);
-  //Serial.println(value);
-
-  // Switch statements dont work on char *
-  if (strcmp(id,"WIPE") == 0) // if id, and WIPE cancel out
-  {
-    windowWiperServo.write(value);
+  // Prevents a bug where if bytes are left in buffer, arduino crashes.
+  while (Wire.available()) {
+    Wire.read();
   }
 }