For a while, I wanted to explorer the possibility of integrating Raspberry PI with Azure IoT Hub and even though, this board does not have a security chip as AZ3166 board does, it still represents a viable option for integrating different sensors with Azure. Moreover, compared to Arduino, which relies on timeless C language, PI allows me to use multiple development options. I’ve experimented with both Node.js and Python to build the integration. In this example, you’ll see how easy it is to integrate PI with Azure IoT using Python.
To get started, I used the remote capabilities of VSCode to develop and debug Python code directly on the device. Check this article on how to connect and configure the remote-ssh extension.
Next, we need to connect Load Cell(HX711) to Raspberry PI. Please check this diagram for details:
Finally, I needed to configure Load Cell(HX711) and Azure IoT Libraries for Python on raspberry PI and provision Azure IoT Hub. Please check this article on how to provision Azure IoT Hub in VSCode.
pip install azure-iot-device
pip install HX711
Testing Solution: The following sample code will measure load cell data and will submit it to Azure IoT hub. Just update the connection string and tune reference units, to adjust the scale. Please check this sample script for more detail on how to calibrate the scale.
#! /usr/bin/python2
import time
import sys
import random
import time
import threading
import RPi.GPIO as GPIO
from azure.iot.device import IoTHubDeviceClient, Message, MethodResponse
from hx711 import HX711
CONNECTION_STRING = "HostName=xxx.azure-devices.net;DeviceId=xxx;SharedAccessKey=xxx"
IOT_MSG = '{{"Weight": {weight}, "Device": "1"}}'
def cleanAndExit():
print("Cleaning...")
GPIO.cleanup()
sys.exit()
GPIO.setwarnings(False)
hx = HX711(5, 6)
hx.set_reading_format("MSB", "MSB")
hx.set_reference_unit(630)
hx.reset()
hx.tare()
def iothub_client_init():
# Create an IoT Hub client
client = IoTHubDeviceClient.create_from_connection_string(CONNECTION_STRING)
return client
def device_method_listener(device_client):
global INTERVAL
while True:
method_request = device_client.receive_method_request()
print (
"nMethod callback called with:nmethodName = {method_name}npayload = {payload}".format(
method_name=method_request.name,
payload=method_request.payload
)
)
if method_request.name == "SetTelemetryInterval":
try:
INTERVAL = int(method_request.payload)
except ValueError:
response_payload = {"Response": "Invalid parameter"}
response_status = 400
else:
response_payload = {"Response": "Executed direct method {}".format(method_request.name)}
response_status = 200
else:
response_payload = {"Response": "Direct method {} not defined".format(method_request.name)}
response_status = 404
method_response = MethodResponse(method_request.request_id, response_status, payload=response_payload)
device_client.send_method_response(method_response)
client = iothub_client_init()
while True:
try:
val = hx.get_weight(5)
msg_txt_formatted = IOT_MSG.format(weight=val)
message = Message(msg_txt_formatted)
print( "Sending message: {}".format(message) )
client.send_message(message)
print( "Message sent" )
hx.power_down()
hx.power_up()
time.sleep(2)
except KeyboardInterrupt:
print ( "IoTHubClient sample stopped" )
Recent Comments