ble_client.py

# Example of interaction with a BLE UART device using a UART service
# implementation.
import Adafruit_BluefruitLE
from Adafruit_BluefruitLE.services import UART
import datetime
import time, sys, signal


# Get the BLE provider for the current platform.
ble = Adafruit_BluefruitLE.get_provider()


myfile = open("out.csv", "a")




# Main function implements the program logic so it can run in a background
# thread.  Most platforms require the main thread to handle GUI events and other
# asyncronous events like BLE actions.  All of the threading logic is taken care
# of automatically though and you just need to provide a main function that uses
# the BLE provider.
def main():
    # Clear any cached data because both bluez and CoreBluetooth have issues with
    # caching data and it going stale.
    ble.clear_cached_data()

    # Get the first available BLE network adapter and make sure it's powered on.
    adapter = ble.get_default_adapter()
    adapter.power_on()
    print('Using adapter: {0}'.format(adapter.name))

    # Disconnect any currently connected UART devices.  Good for cleaning up and
    # starting from a fresh state.
    print('Disconnecting any connected UART devices...')
    UART.disconnect_devices()

    # Scan for UART devices.
    print('Searching for UART device...')
    try:
        adapter.start_scan()
        # Search for the first UART device found (will time out after 60 seconds
        # but you can specify an optional timeout_sec parameter to change it).
        device = UART.find_device()
        if device is None:
            raise RuntimeError('Failed to find UART device!')
    finally:
        # Make sure scanning is stopped before exiting.
        adapter.stop_scan()

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

    #signal.pause()
    # Once connected do everything else in a try/finally to make sure the device
    # is disconnected when done.
    try:
        # Wait for service discovery to complete for the UART service.  Will
        # time out after 60 seconds (specify timeout_sec parameter to override).
        print('Discovering services...')
        UART.discover(device)

        # Once service discovery is complete create an instance of the service
        # and start interacting with it.
        uart = UART(device)

        # Write a string to the TX characteristic.
        uart.write(b'Hello world!\r\n')
        print("Sent 'Hello world!' to the device.")

        # Now wait up to one minute to receive data from the device.
        print('Waiting up to 60 seconds to receive data from the device...')
        print(datetime.datetime.now())

        start_ms = int(round(time.time() * 1000))
        buffer = ''
        suffix = '\r\n'
        finished = False

        while finished != True:
            # read data from BLE device
            received = uart.read(timeout_sec=30)

            # if nothing has been received after timeout then close the session 
            if(received == None):
                finished = True
            else:
                buffer += received.decode('UTF-8')  
                if(buffer.endswith(suffix)):
                    now_ms = str(int(round(time.time() * 1000)))
                    line = now_ms + ',' + buffer
                    myfile.write(line)
                    myfile.flush()
                    buffer = ''
       
    finally:
        # Make sure device is disconnected on exit.
        device.disconnect()
        myfile.close()


# Initialize the BLE system.  MUST be called before other BLE calls!
ble.initialize()

# Start the mainloop to process BLE events, and run the provided function in
# a background thread.  When the provided main function stops running, returns
# an integer status code, or throws an error the program will exit.
ble.run_mainloop_with(main)