The right way to Monitor Room Temperature With a Raspberry Pi

Right this moment, I’m going to indicate you easy methods to monitor ambient room temperature with a Raspberry Pi. We’re going to wire up a temperature sensor, then collect temperature values and ship them to Firebase. This may very well be the beginning of a climate station or another loopy experiments. In my case, we’re going to examine the temperature of a room to ensure our new child puppies don’t get too sizzling or chilly in the course of the day.

What You’ll Want:

  • Raspberry Pi (I'm utilizing a Raspberry Pi 2, however you don’t need to)
  • Breadboard
  • Temperature Sensor
  • A Firebase account (elective)

Discover: I've up to date the source code for this article and constructed an ASP.Net Web API for this mission. Watch them on GitHub to get notified when it’s up to date.

Hooking Up the {Hardware}

I ordered the DS18B20 Waterproof Digital temperature sensor and extras from Adafruit (Get it here) which is a wonderful worth at $10.

Monitor room temperature with Raspberry Pi

Out of the field the wires are stripped, however since I’m placing this in a bread board, I made a decision to solder them. I shortly realized my final roll of solder is reasonably poor high quality, however it would work:

Monitor room temperature with Raspberry Pi

I then wired it as much as the breadboard. There are many diagrams on-line for wiring this up, I hooked

  • Crimson: +3v
  • Yellow: GPIO 4
  • Blue: Floor

Monitor room temperature with Raspberry Pi

The package comes with a 4.7k resistor which you place between the crimson and yellow. The breadboard I exploit is from the Canakit for Raspberry Pi. That is linked to a Raspberry Pi 2, though a Raspberry Pi B would work simply the identical.

Testing the Sensor

The help for the DS18B20 on the Pi makes this half actually trivial. First, you must edit /boot/config.txt:

sudo nano /boot/config.txt

and add the next line 

dtoverlay=w1-gpio

Monitor room temperature with Raspberry Pi

Then save and reboot the Pi.

To check the performance, load within the kernel modules:

sudo modprobe w1-gpio
sudo modprobe w1-therm

Run the next to seek out your machine:

cd /sys/bus/w1/units
ls -la

This can present you the listing your machine is in, based mostly in your serial quantity. It ought to begin with 28x:

Monitor room temperature with Raspberry Pi

cd into that listing, then sort:

cat w1_slave

And, it ought to appear like this:

Monitor room temperature with Raspberry Pi

Search for crc=da YES. The YES means it’s working, and the t=n is the celcius*1000. This verifies the sensor is functioning.

Writing the Temp Gathering Script.

For this step, you can be making a Python script to learn the sensor. You should utilize Nano on the Pi, or use an IDE in your desktop and duplicate the file as much as the Pi. I used PyCharm in Linux to put in writing the script then copied it as much as my Pi with every iteration with the next command:

scp readtemp.py pi@192.168.1.12:/house/pi

This could be a little extra fluid when creating.

The preliminary file we’ll create is a few code lifted from the Adafruit tutorials:

import os
import glob
import time
os.system('modprobe w1-gpio')
os.system('modprobe w1-therm')
base_dir="/sys/bus/w1/units/"
device_folder = glob.glob(base_dir + '28*')[0]
device_file = device_folder + '/w1_slave'

def read_temp_raw():
    f = open(device_file, 'r')
    strains = f.readlines()
    f.shut()
    return strains

def read_temp():
    strains = read_temp_raw()
    whereas strains[0].strip()[-3:] != 'YES':
        time.sleep(0.2)
        strains = read_temp_raw()
    equals_pos = strains[1].discover('t=")
    if equals_pos != -1:
        temp_string = strains[1][equals_pos+2:]
        temp_c = float(temp_string) / 1000.0
        temp_f = temp_c * 9.0 / 5.0 + 32.0
        return temp_c, temp_f

whereas True:
    print(read_temp())
    time.sleep(1)

This can be a tremendous easy script that masses within the kernel modules and reads the machine. The operate read_temp() opens the machine and reads it by parsing via the strains and spitting out Celsius and Fahrenheit values. Then on the backside now we have a loop to do that each second.

python readtemp.py

Your output ought to appear like this:

Monitor room temperature with Raspberry Pi

That is nice, however we are able to’t do a lot with it. At this level you could possibly simply write these values to a file and parse them out later. However, we’re going to retailer these values in a datastore.

In readtemp.py, let’s make some modifications.

Take away the loop:

whereas True:
    print(read_temp())
    time.sleep(1)

And, change it with this:

print str(calendar.timegm(time.gmtime())) + ",' + str(read_temp())

Then add the next strains to the highest:

import calendar
import time

We’re getting nearer! Here's what the ultimate script ought to appear like:

import os
import glob
import subprocess
import calendar
import time
import urllib2
import json

#initialize
os.system('modprobe w1-gpio')
os.system('modprobe w1-therm')

#machine
base_dir="/sys/bus/w1/units/"
device_folder = glob.glob(base_dir + '28*')[0]
device_file = device_folder + '/w1_slave'

# Opens uncooked machine, code modified to mirror difficulty in Raspian
def read_temp_raw():
    catdata = subprocess.Popen(['cat',device_file], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    out,err = catdata.talk()
    out_decode = out.decode('utf-8')
    strains = out_decode.cut up('n')
    return strains

# Reads temperature, outputs farenhiet
def read_temp():
    strains = read_temp_raw()
    whereas strains[0].strip()[-3:] != 'YES':
        time.sleep(0.2)
        strains = read_temp_raw()
    equals_pos = strains[1].discover('t=")
    if equals_pos != -1:
        temp_string = strains[1][equals_pos+2:]
        temp_c = float(temp_string) / 1000.0
        temp_f = temp_c * 9.0 / 5.0 + 32.0
        return temp_f

## Please add some authentication or a secret right here!

url = "https://yourfirebaseapp.firebaseio.com/readings.json'

postdata = {
    'date': str(calendar.timegm(time.gmtime())),
    'temp': str(read_temp())
}

req = urllib2.Request(url)
req.add_header('Content material-Sort','utility/json')
information = json.dumps(postdata)

response = urllib2.urlopen(req,information)

Pushing the Outcomes to Firebase

That is an elective step, however right here we're going to push the outcomes as much as Firebase. You possibly can create an account for free, and I'd encourage you to test it out. The URL would be the url of the mission you create and the title of a JSON file to make use of for storage. For instance:

https://mycooltemperatureapp.firebaseio.com/readings.json

You possibly can change Firebase with any API name at this level, and it’s straightforward to make a POST in Python:

Add the next contains:

import urllib2
import json

Then add the next to the underside:

url="https://mycooltemperatureapp.firebaseio.com/readings.json"
postdata = {
    'date': str(calendar.timegm(time.gmtime())),
    'temp': str(read_temp())
}

req = urllib2.Request(url)
req.add_header('Content material-Sort','utility/json')
information = json.dumps(postdata)

#you do not have to do something with response
response = urllib2.urlopen(req,information)

Now, run the file just a few occasions, and open up your Firebase console. It is best to see one thing that appears like this:

Monitor room temperature with Raspberry Pi

Congrats! You’re now storing information. You possibly can export this to a CSV or create a JavaScript utility to show it. I’ll be masking what we do with this information in a future tutorial.

NOTE: You actually ought to add some authentication to your Firebase database should you care in regards to the information.

Create a CRON Job to Robotically Collect Knowledge

There’s two methods we are able to run this script robotically. We are able to add the loop again in and simply run the Python script and preserve it operating. You should utilize one thing like nohup to run it as a service however that’s a bit of shaky. I’d reasonably simply run the script as soon as a minute with a CRON job. To do that, sort in

crontab -e

To run the cron editor. Add an entry like this:

* * * * * /usr/bin/python /house/pi/readtemp.py

Monitor room temperature with Raspberry Pi

And, save the file. CRON will robotically replace and begin operating this command each minute (or no matter you set it to).

This can make sure that your script is run at common intervals. You possibly can set it to run each minute, hourly, day by day or no matter you’d like. Right here’s some extra data about scheduling cron jobs.

Abstract

I hope this tutorial has helped present you easy methods to monitor ambient air temperature with a Raspberry Pi. If you buy this similar sensor, it’s waterproof which suggests there may be rather more you are able to do with it. You may also hook up a number of sensors to the Pi, separated by serial numbers.

There are tons of neat issues you are able to do with this data, and I encourage you to experiment. In a future tutorial, we’ll take a few of this information I’ve gathered and do one thing with it. Thanks for studying.

You possibly can download the source code for this article at GitHub.

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