Raspberry Pi To SMS – Via the cloud

With the PCB now built and soldered, my attention can turn to the software that powers the BeeSafe and the cloud API that it runs on.

The software is broken down into two parts; software run locally on each BeeSafe and software run in the cloud that manages all inputs, requests, alerts and data.

This post will focus on the software, hosted locally on the Raspberry Pi – the brain of each BeeSafe.

The focus of Raspberry Pi is to help teach people (children) the basics via Python (for more information visit: http://www.raspberrypi.org), so that is the language I have chosen to use on the Pi.

While the BeeSafe PCB has a variety of sensors (Temperature, GPS, Trip Switch and Accelerometer) the main one this post will focus on is temperature. On the board itself I have included a ds18b20 temperature sensor which uses the 1-wire thermal probe. Information on this can be found at: http://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/temperature/ and http://learn.adafruit.com/adafruits-raspberry-pi-lesson-11-ds18b20-temperature-sensing/hardware

Once we have a powered and working Pi, we need to activate the 1-Wire probes, in the command line of your Pi type in :

sudo modprobe w1-gpio

then

sudo modprobe w1-therm

then

cd /sys/bus/w1/devices/

ls

On the page now you should have something that looks like:

w1_bus_master1 and another that looks like “28-000004bb8e9b“. The “28-000004bb8e9b” will be the serial number of the thermal probe, if you have more than one then, they should all be presented alongside each other.

You can directly interface with the thermal probe by typing in

cd /28-000004bb8e9b

and then

cat w1_slave

This will present you with a 2 line read out of data from the thermal probe, it should look something like:

19 01 4b 46 7f ff 07 10 eb : crc=eb YES

19 01 4b 46 7f ff 07 10 eb t=17562

From the output you can see a value called t=17562 which is the temperature but presented raw format, The actual value here is 17.562C. What we need is some code to read this temperature device and give us a useful temperature value.

The code found on the tutorial page at Cambridge (http://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/temperature/) is a perfect starting point for building out with. A copy of the code is below:

# Open the file that we viewed earlier so that python can see what is in it. Replace the serial number as before.
tfile = open(“/sys/bus/w1/devices/YOURW1PROBE/w1_slave”)
# Read all of the text in the file.
text = tfile.read()
# Close the file now that the text has been read.
tfile.close()
# Split the text with new lines (\n) and select the second line.
secondline = text.split(“\n”)[1]
# Split the line into words, referring to the spaces, and select the 10th word (counting from 0).
temperaturedata = secondline.split(” “)[9]
# The first two characters are “t=”, so get rid of those and convert the temperature from a string to a number.
temperature = float(temperaturedata[2:])
# Put the decimal point in the right place and display it.
temperature = temperature / 1000
print temperature

Change to your user directory folder by:

cd ~

and open a new file by typing in:

sudo nano read_temp.py

Copy and paste the above code into the nano editor and be sure to change YOURW1PROBE to the serial number of your probe. If you saved this file as read_temp.py you can run it by typing in:

sudo python ./read_temp.py

it will read the thermal probe for data and print out the temperature in the correct format.. i.e. 17.562C not 17562

Now we can read real world temperature into our software! The next step is to install the libraries to allow us to send this data in an SMS message to our phones!

In your command line update APT using the following commands:

sudo apt-get update

sudo apt-get upgrade

Next we need to install PIP, this is done by:

sudo apt-get install python-pip python-dev build-essential
sudo pip install –upgrade pip
sudo pip install –upgrade virtualenv

and then

sudo pip install twilio

Twilio is a global voice and SMS API provider, they allow you to make & receive voice and SMS (as well as MMS) messages to and from phones to and web services. For this post we are particularly interested in the Sending SMS API which will allow us to send SMS messages from our local device to a cloud service to our mobile phone.

Twilio can be found online at: http://www.twilio.com

If you haven’t already done so, sign up for a trial account. You get $30 of credit to play with the Twilio system. Once you have signed up, you will need to buy a number (these cost $1 per calendar month, but will come out from the trial credit) and verify a phone number that you currently have (such as your mobile).

Once your signed up, in your account page you will need to note down your account SID and auth token. These can be found on the top of:  https://www.twilio.com/user/account

Now we need to start to form a more complex python code, fortunately we can build onto of the code we have written before! To maintain a logical evolution of our files we are going to make a copy of read_temp.py by typing in:

sudo cp ./read_temp.py ./send_sms_temp.py

This will make a copy of our read temp file and save it as send_sms_temp.py

Open up your text editor by typing:

sudo nano send_sms_temp.py

You should see an identical copy of the code we have written before; now we are going to modify this file so that it can assemble an SMS message from our temperature data.

Start by adding:

from twilio.rest import TwilioRestClient

to the top of the page, this will call the Twilio REST API client when the file loads.

Underneath the temperature code, we need to add the following lines:

account_sid = "ACXXXXXXXXXXXXXXXXX"
auth_token = "YYYYYYYYYYYYYYYYYY"
client = TwilioRestClient(account_sid, auth_token)
message = client.messages.create(to="+12316851234", from_="+15555555555",
body="Hello there! The temperature is: " + srt(temperature) + "c")
Substitute the account SID and auth tokens with the ones you wrote down from your user account page: https://www.twilio.com/user/account, then you will need to adjust the ‘to’ value to be a number you wish to SMS. Twilio uses international number standards, so a number in the United States would be ‘+14155555555’ and one from the UK would be ‘+447971234567’.
You will also have to adjust the ‘from’ variable to be the number you have provisioned when you signed up for your trial account. A word of warning, not all numbers from Twilio support SMS messages, particularly SMS messages across geographic locations.
To check which counties can receive messages from which number, check out: https://www.twilio.com/international – when you have signed up test your number works by sending yourself a message from your account portal  (https://www.twilio.com/user/account/developer-tools/api-explorer#POST/2010-04-01/Accounts/{AccountSid}/SMS/Messages.{format})
The srt(temperature) is us telling python to convert the numerical value of temperature into a string value so that it can be added to our outgoing SMS message. Strings and Strings go together, Numbers and Numbers go together, Strings and Numbers do not.
By now your code should look something like this:

from twilio.rest import TwilioRestClient

# Open the file that we viewed earlier so that python can see what is in it. Replace the serial number as before.
tfile = open(“/sys/bus/w1/devices/YOURW1PROBE/w1_slave”)
# Read all of the text in the file.
text = tfile.read()
# Close the file now that the text has been read.
tfile.close()
# Split the text with new lines (\n) and select the second line.
secondline = text.split(“\n”)[1]
# Split the line into words, referring to the spaces, and select the 10th word (counting from 0).
temperaturedata = secondline.split(” “)[9]
# The first two characters are “t=”, so get rid of those and convert the temperature from a string to a number.
temperature = float(temperaturedata[2:])
# Put the decimal point in the right place and display it.
temperature = temperature / 1000
print temperature

account_sid = “ACXXXXXXXXXXXXXXXXX” #Replace this with your account SID
auth_token = “YYYYYYYYYYYYYYYYYY” # Replace this with your auth token
client = TwilioRestClient(account_sid, auth_token)

message = client.messages.create(to=”+12316851234″, from_=”+15555555555″,
body=”Hello there! The temperature is: ” + srt(temperature) + “c”)

This is our complete SMS temperature application!

You should now be able to send yourself a temperature based SMS message by typing in:

sudo python ./send_sms_temp.py

Tada! If all has gone according to plan you should have sent yourself an SMS with the temperature your Raspberry Pi has read from the thermal probe.

How. Cool. Is. That!

Now that you have the basics, the world is your oyster. Imagine being sent a text message when your house is getting too cold. Or a morning message of the temperature outside before you leave the house. Or sending data from an SMS device into a database.. But thats another post..