Fahrenheit vs Celsius

Step 1: Understand the LM35 Sensor

The LM35 is a precision temperature sensor that outputs an analog voltage proportional to the temperature. It outputs 10mV per degree Celsius, making it simple to convert the analog reading to a temperature value. The sensor has three pins: VCC, Output, and GND.

Step 2: Connect the LM35 to Bolt

Place the LM35 on the breadboard and connect it to the Bolt WiFi module as follows:

Make sure the flat side of the LM35 is facing you when identifying the pins from left to right.

Step 3: Power the Bolt Module

Connect the Bolt WiFi module to a power source using a micro-USB cable. Ensure the module connects to your WiFi network and appears online in the Bolt Cloud dashboard.

Step 4: Create a Product on Bolt Cloud

Log in to cloud.boltiot.com. Create a new product with the type set to "Input" and interface type as "GPIO". Link your Bolt device to this product.

Step 5: Configure the Visualization

Click on the Configure icon and add the following JavaScript code to the product code section. This code reads the analog value from the LM35 sensor, converts it to both Celsius and Fahrenheit, and displays both values:

setChartLibrary('google-chart');
setChartTitle('Temperature Monitor');
setChartType('lineGraph');
setAxisName('Time', 'Temperature');
setCrosshair(true);

mul(100/1024);
plotChart('time_stamp', 'temp_celsius', 'Celsius');

// Fahrenheit conversion: F = (C * 9/5) + 32
var celsius = data.temp_celsius;
var fahrenheit = (celsius * 9/5) + 32;

Step 6: Using the Python API for Dual Display

For a more comprehensive solution, you can use the Bolt Python library to read the sensor data and display both temperature scales. Create a file called temp_monitor.py:

import json
from boltiot import Bolt
from time import sleep

API_KEY = "YOUR_API_KEY"
DEVICE_ID = "YOUR_DEVICE_ID"

mybolt = Bolt(API_KEY, DEVICE_ID)

while True:
    response = mybolt.analogRead("A0")
    data = json.loads(response)

    if data["success"] == 1:
        sensor_value = int(data["value"])
        voltage = sensor_value * (5.0 / 1024.0)
        celsius = voltage * 100
        fahrenheit = (celsius * 9.0/5.0) + 32.0

        print("Sensor Value: " + str(sensor_value))
        print("Temperature: {:.2f} C / {:.2f} F".format(celsius, fahrenheit))
        print("---")
    else:
        print("Error reading sensor: " + str(data))

    sleep(5)

Replace YOUR_API_KEY and YOUR_DEVICE_ID with your actual Bolt Cloud credentials. Run the script to see temperature readings printed in both Celsius and Fahrenheit every 5 seconds.