Send None

import random
import time
import sys

import iothub_client
# pylint: disable=E0611
from iothub_client import IoTHubClient, IoTHubClientError, IoTHubTransportProvider, IoTHubClientResult
from iothub_client import IoTHubMessage, IoTHubMessageDispositionResult, IoTHubError, DeviceMethodReturnValue

import board
import busio
from digitalio import DigitalInOut
from adafruit_pn532.i2c import PN532_I2C
reset_pin = DigitalInOut(board.D6)
req_pin = DigitalInOut(board.D12)
i2c = busio.I2C(board.SCL, board.SDA)
pn532 = PN532_I2C(i2c, debug=False, reset=reset_pin, req=req_pin)
pn532.SAM_configuration()

# Your IoT hub device connection string:
CONNECTION_STRING = "HostName=mb-iot-hub.azure-devices.net;DeviceId=RaspberryPi;SharedAccessKey=lu3szoJReJwqvAbXgAqopQ4V6TKnXSYkKN0wP6e4BtI="

# Using the MQTT protocol.
PROTOCOL = IoTHubTransportProvider.MQTT
MESSAGE_TIMEOUT = 10000

# Define the JSON message to send to IoT Hub.
###TEMPERATURE = 20.0
###HUMIDITY = 60
###MSG_TXT = "{\"temperature\": %.2f,\"humidity\": %.2f}"

def send_confirmation_callback(message, result, user_context):
    print ( "IoT Hub responded to message with status: %s" % (result) )

def iothub_client_init():
    # Create an IoT Hub client
    client = IoTHubClient(CONNECTION_STRING, PROTOCOL)
    return client

def iothub_client_telemetry_sample_run():

    try:
        client = iothub_client_init()
        print ( "IoT Hub device sending periodic messages, press Ctrl-C to exit" )

        while True:
            # Build the message with simulated telemetry values.
            uid = pn532.read_passive_target(timeout=0.5)
            print(end="", flush=True)
            if uid is None:
                continue
            MSG_TXT = bytearray([int(i) for i in uid])
            #temperature = TEMPERATURE + (random.random() * 15)
            #humidity = HUMIDITY + (random.random() * 20)
            msg_txt_formatted = MSG_TXT
            message = IoTHubMessage(msg_txt_formatted)

            # Add a custom application property to the message.
            # An IoT hub can filter on these properties without access to the message body.
            #prop_map = message.properties()
            #if temperature > 30:
              #prop_map.add("temperatureAlert", "true")
            #else:
              #prop_map.add("temperatureAlert", "false")

            # Send the message.
            print( "Sending message: %s" % message.get_string() )
            client.send_event_async(message, send_confirmation_callback, None)
            time.sleep(1)

    except IoTHubError as iothub_error:
        print ( "Unexpected error %s from IoTHub" % iothub_error )
        return
    except KeyboardInterrupt:
        print ( "IoTHubClient sample stopped" )

if __name__ == '__main__':
    print ( "IoT Hub Quickstart #1 - Simulated device" )
    print ( "Press Ctrl-C to exit" )
    iothub_client_telemetry_sample_run()