1  """
 2  Demonstration of a Bluefruit BLE Central for Circuit Playground Bluefruit. Connects to the first BLE
 3  UART peripheral it finds. Sends Bluefruit ColorPackets, read from three accelerometer axis, to the
 4  peripheral.
 5  """
 6  
 7  import time
 8  
 9  import board
10  import busio
11  import digitalio
12  import adafruit_lis3dh
13  import neopixel
14  
15  from adafruit_bluefruit_connect.color_packet import ColorPacket
16  
17  from adafruit_ble import BLERadio
18  from adafruit_ble.advertising.standard import ProvideServicesAdvertisement
19  from adafruit_ble.services.nordic import UARTService
20  
21  
22  def scale(value):
23      """Scale an value from  (acceleration range) to 0-255 (RGB range)"""
24      value = abs(value)
25      value = max(min(19.6, value), 0)
26      return int(value / 19.6 * 255)
27  
28  
29  i2c = busio.I2C(board.ACCELEROMETER_SCL, board.ACCELEROMETER_SDA)
30  int1 = digitalio.DigitalInOut(board.ACCELEROMETER_INTERRUPT)
31  accelerometer = adafruit_lis3dh.LIS3DH_I2C(i2c, address=0x19, int1=int1)
32  accelerometer.range = adafruit_lis3dh.RANGE_8_G
33  
34  neopixels = neopixel.NeoPixel(board.NEOPIXEL, 10, brightness=0.1)
35  
36  ble = BLERadio()
37  
38  uart_connection = None
39  # See if any existing connections are providing UARTService.
40  if ble.connected:
41      for connection in ble.connections:
42          if UARTService in connection:
43              uart_connection = connection
44          break
45  
46  while True:
47      if not uart_connection:
48          print("Scanning...")
49          for adv in ble.start_scan(ProvideServicesAdvertisement, timeout=5):
50              if UARTService in adv.services:
51                  print("found a UARTService advertisement")
52                  uart_connection = ble.connect(adv)
53                  break
54          # Stop scanning whether or not we are connected.
55          ble.stop_scan()
56  
57      while uart_connection and uart_connection.connected:
58          r, g, b = map(scale, accelerometer.acceleration)
59  
60          color = (r, g, b)
61          neopixels.fill(color)
62          color_packet = ColorPacket(color)
63          try:
64              uart_connection[UARTService].write(color_packet.to_bytes())
65          except OSError:
66              try:
67                  uart_connection.disconnect()
68              except:  # pylint: disable=bare-except
69                  pass
70              uart_connection = None
71          time.sleep(0.3)