add an oled demo

examples/oleddemo/oleddemo.ino

@@ -0,0 +1,57 @@
+// OLED demo for accelerometer readings from Adafruit MSA301
+
+#include <Wire.h>
+#include <Adafruit_SSD1306.h>
+#include <Adafruit_MSA301.h>
+#include <Adafruit_Sensor.h>
+
+Adafruit_MSA301 msa;
+Adafruit_SSD1306 display = Adafruit_SSD1306(128, 32, &Wire);
+
+
+void setup(void) {
+  Serial.begin(115200);
+  Serial.println("Adafruit MSA301 demo!");
+  
+  // Try to initialize!
+  if (! msa.begin()) {
+    Serial.println("Failed to find MSA301 chip");
+    while (1) { delay(10); }
+  }
+  Serial.println("MSA301 Found!");
+
+  // SSD1306_SWITCHCAPVCC = generate display voltage from 3.3V internally
+  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { // Address 0x3C for 128x32
+    Serial.println(F("SSD1306 allocation failed"));
+    for(;;); // Don't proceed, loop forever
+  } 
+  display.display();
+  delay(500); // Pause for 2 seconds
+  display.setTextSize(1);
+  display.setTextColor(WHITE);
+  display.setRotation(0);
+}
+
+void loop() {
+  sensors_event_t event; 
+  msa.getEvent(&event);
+
+  display.clearDisplay();
+  display.setTextSize(1);
+  display.setCursor(0,0);
+  display.println("- Adafruit MSA301 -");
+
+  /* Display the results (acceleration is measured in m/s^2) */
+  Serial.print("\t\tX: "); Serial.print(event.acceleration.x);
+  Serial.print(" \tY: "); Serial.print(event.acceleration.y); 
+  Serial.print(" \tZ: "); Serial.print(event.acceleration.z); 
+  Serial.println(" m/s^2 ");
+
+  display.setCursor(0, 8);
+  display.print("X: "); display.print(event.acceleration.x); display.println(" m/s^2 ");
+  display.print("Y: "); display.print(event.acceleration.y); display.println(" m/s^2 ");
+  display.print("Z: "); display.print(event.acceleration.z); display.println(" m/s^2 "); 
+  display.display();
+
+  delay(100);
+}