Introduction: Tiny Message Board

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We will make a tiny connected message board with a 0.96" OLED display that can be controlled from your phone. We will use the IFTTT "DO" app to set and clear the reminder so that no extra hardware will be required besides the OLED display. In addition to the reminder, our tiny message board can display 3 other lines, which we will use to display the daily weather temperature forecast and a surf report, which will be pushed via a couple of IFTTT recipes.

The message board uses a Particle photon (Arduino compatible) for the brain and internet connectivity and a 128x64 monochrome OLED display.

Let's get started.

Step 1: You Will Need...

  1. A Particle photon microcontroller $20
  2. A 0.96" I2C Monochrome OLED display $10. Also available on the ADAFRUIT web store.
  3. A small Breadboard $3
  4. Breadboard wiring
  5. An enclosure for the project (a mint box will work)

Step 2: Wiring

The I2C display requires only 4 connections:

  • GND and VCC, which we can conveniently get from the Photon's pins 3V3 and GND, and
  • SDA and SCL which we will connect to the Photon's D0 and and D1 respectively.

The display consists of 128x64 pixels, which corresponds to 8 rows of 8 pixels (font size 1) or 4 lines of 16 pixels if we use a font size of 2. Our display is "monochrome", but the first line of text is yellow and the rest is blue, so we will use the first line for our reminder and the other 3 lines for other information such as surf report and weather for the day (or whatever else is important to you).

Step 3: Software

We will use the Particle web IDE to write and upload the software to the Photon. I will assume that you have already successfully gone through the registration steps outlined here: getting started.

Assuming that your Photon is now connected to the Cloud via your Wi-Fi access point, we require a few things for this project:

1. Adding the libraries required by our OLED display

Because library code needed modifications, I chose to include the files in the project directly instead of "including" them from the web IDE. To add a library, click on the small + icon at the top right of the Build IDE and type in the name (ADAFRUIT_GFX or ADAFRUIT_SSD1306). This will create a pair of files (.cpp and .h) where you can paste each file. You should end up with 5 files total, the .ino application and the 4 library files. The modifications account for the fact that some libraries and functions are already defined for the photon and also for changing the base I2C address of the display (we used 0x3C required for this display).

2. Creating a Cloud function

To create a function that can be called remotely from a smartphone over the internet, we will need to declare it as such during setup:

Spark.function("SetReminder", SetReminder);

Here we declare a function called "SetReminder", that will call the SetReminder function defined in our tinymessageboard.ino code. The code for that function is very simple:

int SetReminder(String message) {
ClearMessage(0);
if (message.length() > 0)
showMsg(0, message);
}

where 0 is the "line" number. Similarly, we will add a couple of other functions, SetWeather and SetSurf to remotely set the temperature and the surf report for today.

Code is attached.

Attachments

Step 4: Controlling the Message Board From Our Phone Via IFTTT

Thanks to Particle's Cloud and a web service called IFTTT (If This Then That), setting a message on our message board is a very simple task that does not require programming. Head over to IFTTT and create an account if you do not have one.

First we will create a way to set our reminder from our phone using an IFTTT "DO" button. In this case, the reminder is that the sprinkler system is off (rain delay). Download the IFTTT "DO" app on your phone and let's create a button to represent our first "message". You can create the recipe on either your phone or the IFTTT web site using the "DO" tab. Lets call it "Sprinkler is OFF" or whatever your reminder needs to be. For the channel, select the Particle channel and lets "Call a function" on our device. Find the function on your photon called SetReminder and set the parameter of the function to be your reminder; in this case "Sprklr OFF" (you only have about 10 characters, unless to go to a smaller font size). Now you have a button that will set the reminder remotely on your photon. To clear the reminder, create a second DO button calling the same function, but this time pass in an empty parameter.

Step 5: Displaying the Weather

Now let's create an IFTTT recipe that will automatically update the temperature for today. We have chosen to display the low and high for the day.

Create a new recipe and select the "Weather" channel. At the create trigger, select "Today's weather report" and select 6:00AM for the time of the update. For the "That" part, we will call the SetWeather function on our device. Select "SetWeather" on your "photon device name". Edit the information to show the low and high temperature as shown (the "ingredients" of your recipe).

That's it. At 6AM every day, the IFTTT channel will push the weather to your device.

More information on Particle and IFTTT can be found here.

Step 6: Displaying the Surf Report

The method for displaying the surf report is similar this time using the Surfline channel. You can chose to display different fields but keep in mind that anything more than 10 characters will display in a smaller font.

See picture for details.

Step 7: In Conclusion

There are many things you can display using this small OLED display. We have chosen to display text, but the graphics library can also display graphics and perform animations such as scrolling.

Keep in mind that Photons can communicate with each other via the Particle cloud, so you could use this display to show the status of your other projects provided they also use a Photon.

Have fun and post in the comments if you find other applications for your tiny message board! Can you find a way to show water temperature and humidity? Let me know...