MeArm Bluetooth LE Python example (low level)

MeArm_BLE_Test.py

#!/usr/bin/env python
#
# Description: Low level example of sending BLE messages to a MeArm Brain Board fitted with the HM-11 Bluetooth LE module
#
# 17/02/2016        Wayne Keenan    ([email protected])
#
# Deps:
#           1) MeArm should have the MeArm_BLE sketch programmed, found here: https://codebender.cc/sketch:244546
#           2) Adafruit Python BLE libray (see below)
#
# Python BLE Library Setup (for Linux and Mac):
#
# git clone https://github.com/adafruit/Adafruit_Python_BluefruitLE.git
# cd Adafruit_Python_BluefruitLE/
# python setup.py install --user
#
# On Mac this will work out of the box for the system default Python that is installed by default in MacOS X.
# On Linux please see the "Linux & Raspberry Pi Requirements" section in the Adafruit GitHub link above
#-----------------------------------------------------------------------------------------------------------------------

import array
import uuid
import time
import Adafruit_BluefruitLE

#import logging
#logging.basicConfig(level=logging.DEBUG)

# Define service and characteristic UUIDs used by the HM-11 module.
HM11_SERVICE_UUID = uuid.UUID('0000ffe0-0000-1000-8000-00805f9b34fb')
HM11_CHAR_UUID    = uuid.UUID('0000ffe1-0000-1000-8000-00805f9b34fb')

ble = Adafruit_BluefruitLE.get_provider()

def main():
    ble.clear_cached_data()
    adapter = ble.get_default_adapter()
    adapter.power_on()
    print('Using adapter: {0}'.format(adapter.name))
    ble.disconnect_devices([HM11_SERVICE_UUID])

    print('Searching for MeArm (HM-11) device...')
    try:
        adapter.start_scan()
        device = ble.find_device(service_uuids=[HM11_SERVICE_UUID])
        if device is None:
            raise RuntimeError('Failed to find HM11 device!')
    finally:
        adapter.stop_scan()

    print('Connecting to device...')
    device.connect()  # Will time out after 60 seconds, specify timeout_sec parameter

    try:
        print('Discovering services...')
        device.discover([HM11_SERVICE_UUID], [HM11_CHAR_UUID])
        hm11 = device.find_service(HM11_SERVICE_UUID)
        tx = hm11.find_characteristic(HM11_CHAR_UUID)

        print('Sending messages to device...')

# Everything above this line is boilerplate.
#-----------------------------------------------------------------------------------------------------------------------
# The meat...

    # Valid array values are specified by the MeARM_BLE Arduino sketch source code (see the deps at the top)
    #
    # In Summary: [Magic, FunctionCode, BaseServoAngle, LeftServoAngle, RightServoAngle, ClawServoAngle]
    #
    #   Magic is always 0x00
    #   FunctionCode 0x02 for 'SetServoAngles' mode
    #   *ServoAngle is in the range 0 - 179

        print('Setting all Servo Angles to 90')
        tx.write_value(array.array('B', [0x00, 0x02, 90, 90, 90, 90]))
        time.sleep(2)

        print('Setting Base Servo Angle to 50')
        tx.write_value(array.array('B', [0x00, 0x02, 50, 90, 90, 90]))
        time.sleep(2)

        print('Setting all Servo Angles to 90')
        tx.write_value(array.array('B', [0x00, 0x02, 90, 90, 90, 90]))
        time.sleep(2)

        print('Here endith the lesson')

#-----------------------------------------------------------------------------------------------------------------------
# Everything below this line is boilerplate.

    finally:
        device.disconnect()


ble.initialize()
ble.run_mainloop_with(main)