an-iot-thermostat.md

description
Applying the hard-earned knowledge so far, let us build a simple IoT gadget that monitors the surrounding temperature.

An IoT thermostat

Components required

• Analog Temperature Sensor - 1
• NodeMCU - 1
• Jumpers

Getting Temperature values

In order to read temperature values from LM35 temperature sensor, do this:

from machine import ADC        # imports the Pin and ADC class from the machine module
import time

temp = ADC(0)                  # creates a temp object to read
while True:                    # repeats the statements within forever
    tempSense = temp.read()    # reads the 10-bit analog value from LM35
    print(tempSense)           # prints the tempSense value on the monitor
    time.sleep_ms(100)         # wait for 1/10th of a second before reading the next value

Publishing messages to a Adafruit.io

In order to publish messages to an MQTT broker, we only need to import the MQTT client class from the umqtt.simple module available to us in the MicroPython firmware.

To do so, add the following statements to your previous code:

{% code-tabs %} {% code-tabs-item title="publishTemp.py" %}

from machine import ADC
import time
from umqtt.simple import MQTTClient
broker = 'io.adafruit.com'
user = 'icreate'
topic = b'icreate/f/pot'
key = '697847b8dfbb4b43b8f06bf7ed037887'
myClient = MQTTClient('nodeMCU', broker, 1883, user, key)
myClient.connect()

while True:
    myClient.publish(topic,str(ADC(0).read()))
    time.sleep(1)
myClient.disconnect()

{% endcode-tabs-item %} {% endcode-tabs %}

{% code-tabs %} {% code-tabs-item title="knobDegree.py" %}

from machine import ADC
import time

def knobToDegrees(maxVolt=3.3):
    knobVal = 0
    knobVal = ADC(0).read()
    knobVolt = knobVal * (3.3/1024)
    print("Voltage at Pin A0 of NodeMCU",end='- ')
    print(knobVolt, end=' Volts\n') 
    knobRotation = knobVolt * (270/3.3)
    print("Knob Rotation",end='- ')
    print(knobRotation, end=' degrees\n')
    
knobToDegrees()    

{% endcode-tabs-item %} {% endcode-tabs %}