Add CAN example

example/can_example/sketch_can_example/sketch_can_example.ino

@@ -0,0 +1,30 @@
+#include <mcp2515.h>
+
+MCP2515 mcp2515(10);
+
+void setup() {
+  Serial.begin(9600);
+  mcp2515.reset();
+  mcp2515.setBitrate(CAN_50KBPS);
+  mcp2515.setNormalMode();
+  Serial.println("begin");
+}
+
+void loop() {
+  char message[9];
+  message[8] = '\0';
+  struct can_frame send_frame;
+  struct can_frame receive_frame;
+  int read = Serial.readBytesUntil('\n', send_frame.data, 8);
+  if (read > 0) {
+    send_frame.can_id = 0x001;
+    send_frame.can_dlc = read;
+    mcp2515.sendMessage(&send_frame);
+    Serial.println("sent");
+  }
+  if (mcp2515.readMessage(&receive_frame) == MCP2515::ERROR_OK) {
+    memcpy(message, receive_frame.data, 8);
+    Serial.println(message);
+  }
+  Serial.println("Waiting for next message\n");
+}