added microbit example code

examples/microbit_serial_example.py

@@ -0,0 +1,41 @@
+from microbit import *
+import utime
+import math
+
+def norm_acc(x):
+    new = round(min(max((x + 2000)/4000, 0.0), 1.0), 4)
+    return str(new)
+
+last_acc_msg = ""
+
+def send_accelerometer_data():
+    global last_acc_msg
+    if accelerometer.get_strength() > 1500:
+        x, y, z = accelerometer.get_values()
+        accs = map(norm_acc, [x,y,z])
+        out = ','.join(accs)
+        if out != last_acc_msg:
+            print(out)
+            last_acc_msg = out
+
+def receive_and_display():
+    if uart.any():
+        data = uart.readline()
+        if data is None:
+            return
+        data = data.decode('utf-8').strip().split(',')
+        if len(data) == 3:
+            try: 
+                x, y, z = map(float, data)
+                display.clear()
+                display.set_pixel(0, 4 - min(math.floor((x + 0.2) * 4), 4), 9)
+                display.set_pixel(2, 4 - min(math.floor((y + 0.2) * 4), 4), 9)
+                display.set_pixel(4, 4 - min(math.floor((z + 0.2) * 4), 4), 9)
+            except Exception as e:
+                pass
+
+uart.init(baudrate=115200)
+
+while True:
+    send_accelerometer_data()
+    receive_and_display()