Welcome to the Arduino tutorial I wish existed when I started playing with hardware.
Learn how to send an SMS text message in Python by pushing a button on your Arduino!
A couple years ago I was very new to hardware, hadn't touched a solder in over a decade, never used an Arduino or Raspberry Pi.
I wanted to play around with an Arduino but I didn't know where to begin. In the Fall of 2012 I joined Tindie as the first employee and that fueled my interest in hardware even more.
I'm a software engineer, love programming and preferred to program in Python on my Arduino instead of learning another new language. This was partially because all the cool third party libaries I love have Python bindings.
The tutorial is for you if:
- You have never used an Arduino or have some experience and want to learn how to run Python programs on your Arduino.
- You have some understanding of how to program. Teaching Python programming or programming in general is more than I could tackle here.
- You are comfortable using the command line.
- You know what GitHub is, have a basic understanding how to use it and know how to fork a repository.
- Regardless of skill level, you want to learn how to program your Arduino to send a SMS text message at the push of a button!
Arduinos are awesome! But an Arduino doesn't in and of itself do anything. In some ways it's like a whiteboard: the whiteboard doesn't write on itself, it’s what you do with the whiteboard that makes it a useful tool.
This is why Arduino is called a platform. It enables you to build all kinds of amazing things, but it's a blank canvas.
To quote SparkFun:
“Arduino is an open-source electronics prototyping platform based on flexible, easy-to-use hardware and software. It’s intended for artists, designers, hobbyists, and anyone interested in creating interactive objects or environments. Or more simply, you load on some code and it can read sensors, perform actions based on inputs from buttons, control motors, and accept shields to further expand its capabilities. Really, you can do almost anything."
If you feel the need to purchase a book and have no electronics background I would suggest Getting Started with Arduino.
It's very basic and I read it cover-to-cover in one afternoon.
Purchasing an Arduino
I have been lucky enough to get all my Arduinos (yes I have a collection) at technical conferences (SendGrid was giving them away at PyCon), hackathons, and Maker Faire.
Before you purchase your Arduino I suggest you read through this tutorial especially the"Getting started" section because you might want to purchase a kit that includes an Arduino.
When you purchase an Arduino, you are purchasing a circuit board with a microcontroller.
A microcontroller is a small computer; there are microcontrollers in almost everything: microwaves, coffee machines, power drills, you get the idea. It doesn't even come with the USB cord you need to connect it to your laptop.
Here is what an Arduino looks like out of the box.
The top one is a plain Arduino Uno, the bottom one is an Arduino Uno SMD I got at Maker Faire (hence the "Make: Special Edition" printed on the board) but they are almost exactly the same. They have different microprocessors, but you can do the same types of hacks with both.
I have found it's very helpful to buy a kit that has some of the nice add-ons you need to build some sweet stuff.
The kits often contain a USB cord and some of the components you need to get started. Here is the kit I bought on Amazon; it’s nothing too fancy and less than $20:
Plug In Your Arduino
1 Install the Arduino IDE. This includes some instructions for how to get your computer to recognize the Arduino.
2 I find it useful to ensure the computer recognizes the Arduino before I start programming. What if you write your whole program and can't get it to talk to the board? Specifically, this means ensuring the correct board and serial port are selected: 7 | Select your board and 8 | Select your serial port. If your computer can successfully talk to your Arduino, then the ON button (green one) should come on and the L button blinks orange:
3 If you want to see something cool, stick the longer (positive) end of an LED in the #13 pin (a pin is a slot on the Arduino board) and the shorter (negative) end in the GND pin (GND stands for "ground").
Just don't leave it plugged in for too long! The LED will draw too much current, burn really bright, get really hot and then die.
To read more awesomeness about LEDs, checkout this tutorial from Adafruit that includes some very interesting LED knowledge:
"One of the best things about modern LEDs is all the colors they come in. It used to be that LEDs were only red or maybe yellow and orange, which is why early electronics from the 70s and 80s only had red LEDs. The color emitted from an LED has to do with what type of material they are made of. So red, for example, is made with Gallium Arsenide. Since then, scientists have experimented with many other materials and figured out how to make other colors such as green and blue, as well as violet and white."
LOAD UP THE FIRMWARE
1 To program the Arduino using the IDE you must use the Processing program language. Although this isn't necessarily that hard, all the awesome 3rd party libraries (e.g. Twilio) don't have Processing bindings. So let's use something a little more fun: Python!
2 There are many different ways to talk to your Arduino using Python. The first step is to install the StandardFirmata on your Arduino (Firmatta is a protocol used to by a computer to communicate with the microcontroller).
- Plug in your Arduino via USB
- Open the Arduino IDE, select: File > Examples > Firmata > StandardFirmata
- Click the "Upload" button (arrow that points to the right)
- You should see a success message at the bottom of the IDE ("Done uploading")
Once you have the Firmatta installed you can talk to the Arduino using pyFirmatta or any library built on top of pyFirmatta.
In the following example we are going to use a library called BreakfastSerial that is built on top of pyFirmatta (meaning is abstracts away some of the complexities of pyFirmatta, much like Python abstracts away complexities of C).
BreakfastSerial is a great beginner library and can get you going fast. However, if you want to do more complex things you will likely need to drop down to the pyFirmatta layer.
For example, BreakfastSerial does a great job of abstracting away a lot of the physics of circuits and you don't have to worry about analog vs digital pins on the Arduino, but as you gain experience I have found it's fun to dig deeper and understand more of what's going on "behind the scenes".
Send a SMS Text Message
We are going to go through a simple example where you can send a SMS text message by pressing a button on your Arduino!
1 Assemble all the parts you need:
- 1 breadboard (That is the white thing with all the holes in it. The one pictured came with my kit and is a solderless breadboard. Since it doesn't require soldering, it is reusable and thus great for prototyping)
- 6 wires (color and length don't matter - they are all the same)
- 1 10K ohm resistor
- 1 button
- 1 LED (I'm using a red one in the photos below)
2 Hook up your arduino according to this diagram (replicated below). It doesn't matter if your Arduino looks exactly the same, the important part is that you hook the wires up exactly as in the picture and into the correct pins on the board (#2, 5V and GND).
It should look like the following photos (apologies that it is hard to see the little black button, but it is there on the breadboard). I also placed an LED in pin #13 as demonstrated in the Plug in Your Arduino step. You can see it sitting next to the board in the first photo and in pin #13 in the second photo:
If you're wondering "What is a resistor? Why do I need a resistor?" you should read this great answer on Electronics StackExchange. Here are all the resistors in my kit with the resistance labeled; I chose the one that says "10K":
If your resistors don't have a handy label on them you can still tell the resistance from the colored markings on the resistor itself. Here is a guide to decoding the colored markings.
2 I have written some code that we are going to run on your Arduino. Fork my txtduino repository on GitHub.
3 My code assumes you have LED hooked up to pin #13 and the button hooked up to pin #2. If you have used different pins, you will need to modify the code.
4 Ensure you install the requirements (txtduino depends on both pyFirmatta and BreakfastSerial, so both those libraries will be installed when you install the requirements):
$ pip install -r requirements
twilio_account_sid = 'PUT YOUR TWILIO ACCT SID HERE' twilio_auth_token = 'PUT YOUR TWILIO AUTH TOKEN HERE' your_phone_number = 'PUT YOUR PHONE NUMBER HERE' your_twilio_number = 'PUT YOUR TWILIO PHONE NUMBER HERE'
7 Run the code on your Arduino!
$ python txtduino.py
The LED will blink several times while establishing a connection to the Arduino. After you see the message "Connecting to ..." you can now try sending your text message by pressing down firmly on the button.
I have added debugging statements so you can ensure your button press is registering. If you don't see the message "press down" then press the button again harder.
If all is hooked up correctly you should see the following output:
8 It can take several minutes for Twilio to send the text message, but usually quite quickly you'll see:
Thanks For Stopping By!
Hope you enjoyed the tutorial! Isn't hardware awesome?