Sensor Tutorial

note

Using a Notecarrier-AF? The AF is no longer available for purchase, but we still support it. You can complete the Notecarrier-F version of this tutorial with that board.

Don't see your favorite hardware here? Rest assured the Notecard works with virtually every MCU and SBC available. If you can't figure out how to complete this tutorial let us know in our forum and we can help you out.

Introduction

This tutorial should take approximately 40-50 minutes to complete.

In this tutorial, you'll learn how to take sensor readings from a Device and send readings to your Notecard and the Blues Wireless Notehub. You'll use C/C++ (Arduino/Wiring) running on a Adafruit Feather M4 Express wired up to Notecarrier-F hardware. If you would like to use a different language, board, or Notecarrier, modify the dropdowns at the top of this guide.

The tutorial uses mock sensor readings for simplicity, but feel free to hook up a physical sensor of your choice and use that instead.

note

If you get stuck at any point during this tutorial, the full source for each example is available on GitHub:

• View this example's source code on GitHub.

Set up Hardware

First, you’ll need to get all of your hardware connected. Follow the instructions below to connect your Adafruit Feather M4 Express and Notecard mounted on a Notecarrier-F.

In order to complete this guide, you’ll need the following:

• Notecard mounted to Notecarrier-F.

• Any Arduino-capable Microcontroller (MCU) with Feather headers. We'll be using the Adafruit Feather M4 Express, but any Feather that can be programmed with the Arduino IDE will do.

• Micro USB to USB-A cable.

Connect the sensor and MCU to the Notecarrier

1. Plug your Feather-compatible Adafruit Feather M4 Express device into the Feather headers on the Notecarrier-F.

2. Attach your microcontroller to your computer with a Micro USB to USB-A cable, using the Micro USB port on the microcontroller.

   

Create a Notehub Project

Now that your hardware is all connected, let’s create a new Notehub project to receive sensor readings from your Notecard.

1. Navigate to notehub.io and log-in, or create a new account.

2. Using the New Project card, give your project a name and ProductUID.

   

NOTE: The ProductUID must be globally unique, so we recommend a namespaced name like "com.your-company.your-name:your_product".

3. Take note of your ProductUID. This identifier is used by Notehub to associate your Notecard to your project.

   

Write Firmware

Configure the Arduino IDE

For this portion of the guide, we'll be using the Arduino IDE, so be sure to install version 2.0+ if you haven't already.

Once installed, we'll need to add support for your Adafruit Feather M4 Express Board.

Configure the Arduino Boards Manager to use the Feather M4 Express

1. Start the Arduino IDE and open the Preferences menu.

   

2. Copy the following path https://adafruit.github.io/arduino-board-index/package_adafruit_index.json into the "Additional Board Manager URLs" field. If there's already something in the box, then add a comma to separate the URLs.

   

3. Click OK, then open the Boards Manager from the Tools > Board: [board name] > Boards Manager... menu.

   

4. Before installing support for Adafruit SAMD boards (like the Feather M4), you'll need to install Arduino SAMD drivers. Search for "Arduino SAMD" and click the Install button to add Arduino SAMD Boards (32-bits ARM Cortex-M0+) support to the Arduino IDE.

   

5. Next, search for "Adafruit SAMD" and click the Install button to add Adafruit SAMD Boards to the Arduino IDE.

   

6. Once the installation is complete, click the Close button.

7. Plug Feather device in, select Adafruit Feather M4 Express (SAMD51) from the Tools > Board menu, and select the appropriate Port for your device.

   

Great job, now you're ready to write some firmware!

Arduino Sketch

When communicating with the Notecard over I2C, you'll want to use the note-arduino library. The code snippets below provide everything you need to talk to the Notecard over I2C in Arduino.

warning

The Notecarrier-F provides only an I2C connection between a Feather MCU host and the Notecard; it does not facilitate Serial communication between devices.

Configure your Notecard

Install the Notecard Arduino Library

1. To use the note-arduino library, you'll need to add it to the Arduino IDE.

2. Click on Tools > Manage Libraries...

3. Search for "Blues" in the input box and click the "Install" button next to the "Blues Wireless Notecard" result.

   

4. Create a new sketch and select the Sketch > Include Library > Contributed Libraries > Blues Wireless Notecard menu option, to add the following include to your sketch:

   COPY
   #include <Notecard.h>

Set Up Your Notecard

1. Now, configure a Serial interface. Serial will be used to log information to the Serial terminal of the Arduino IDE.

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   #define usbSerial Serial

2. Next, add a definition for your ProductUID using the value you specified when creating your Notehub project.

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   #define productUID "com.your-company.your-name:your_product"

3. Above the setup() and loop() functions, declare a global object to represent the Notecard.

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   Notecard notecard;

4. In the setup() function, initialize the usbSerial object and tell the Notecard library to use this serial object for sending debug output.

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   delay(2500);
   usbSerial.begin(115200);

5. Initialize an instance of the Notecard class and initialize an I2C connection to the Notecard using the notecard.begin() function. Then, use setDebugOutputStream() to link the debug output to usbSerial with the following code:

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   notecard.begin();
   notecard.setDebugOutputStream(usbSerial);

6. Now, we'll configure the Notecard. Using the hub.set request, we associate this Notecard with the ProductUID of your project and set the Notecard to operate in continuous mode, which indicates that the device should immediately make a connection to Notehub and keep it active.

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   J *req = notecard.newRequest("hub.set");
   JAddStringToObject(req, "product", productUID);
   JAddStringToObject(req, "mode", "continuous");
   notecard.sendRequest(req);

   The lines above build-up a JSON object by adding two string values for product and mode, and then fires the request off to the Notecard with the sendRequest() function.

7. Click the Upload button (right arrow icon) to flash firmware to your device.

   

8. Open the Arduino Serial Monitor. If everything has been connected and configured properly, you'll see a few debug messages, including the JSON object you sent, as well as the response from the Notecard {}.

   

Read from the sensor

Now that you've configured your Arduino to communicate with the Notecard, let's grab some pseudo sensor readings.

note

If you have your own sensor, feel free to hook it up and use your own values instead of this tutorial's mocked ones.

1. To generate mock sensor readings you'll use the NotecardPseudoSensor library. To add the library to Arduino IDE start by clicking on Tools > Manage Libraries...

2. Search for “NotecardPseudoSensor” in the input box and click the Install button next to the “Blues Wireless Notecard Pseudo Sensor” result.

   

3. Add the following include to the top of your sketch:

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   #include <NotecardPseudoSensor.h>

4. Next, include the following namespace under your includes.

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   using namespace blues;

5. After that, create an instance of NotecardPseudoSensor with the line of code below. Place this directly under your existing Notecard notecard statement.

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   NotecardPseudoSensor sensor(notecard);

6. Finally, place the following code in your loop function, which generates mock temperature and humidity readings, prints them to the console, and then waits 15 seconds before exiting the loop.

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   float temperature = sensor.temp();
   float humidity = sensor.humidity();
   
   usbSerial.print("Temperature = ");
   usbSerial.print(temperature);
   usbSerial.println(" *C");
   usbSerial.print("Humidity = ");
   usbSerial.print(humidity);
   usbSerial.println(" %");
   
   delay(15000);

7. Upload this code to your Adafruit Feather M4 Express. Open the Serial Monitor and you'll see temperature and humidity readings every 15 seconds.

   

Send Sensor Readings to the Notecard

Now that we're getting sensor readings, let's send these to our Notecard.

1. To send a sensor reading to the Notecard, we'll need to construct a new JSON request to the note.add API that includes a new Notefile name (sensors.qo), sets the sync field to true to instruct the Notecard to sync to Notehub immediately, and finally, sets the body to the sensor temperature and humidity. Add the following in loop right after the usbSerial commands to print out readings.

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   J *req = notecard.newRequest("note.add");
   if (req != NULL)
   {
     JAddStringToObject(req, "file", "sensors.qo");
     JAddBoolToObject(req, "sync", true);
     J *body = JAddObjectToObject(req, "body");
     if (body)
     {
       JAddNumberToObject(body, "temp", temperature);
       JAddNumberToObject(body, "humidity", humidity);
     }
     notecard.sendRequest(req);
   }

2. Upload this code to your device. After reboot, the Serial monitor will update to display the response from the note.add request (the total number of Notes in the notefile) each time you add a new reading.

   

View Data in Notehub

Once you start capturing readings, your Notecard will initiate a connection to Notehub and will start transferring Notes. Depending on signal strength and coverage in your area, it may take a few minutes for your Notecard to connect to Notehub and transfer data.

1. Return to notehub.io and open your project. You should see your notecard in the Devices view.

   

2. Now, click on the Events left menu item. Once your sensor Notes start syncing, they’ll show up here.

   

Congratulations!

You’ve successfully connected your Adafruit Feather M4 Express and sensor to your Notecard!

Now you're ready to connect this Notecard project to a cloud application! Take a look at our routing tutorials, which cover a number of popular cloud applications and data visualization tools.

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During this tutorial, you set your Notecard into continuous mode, which maintains an active network connection and enables faster syncs with Notehub. It doesn't have much impact on data usage, but it will draw more power. If you're connected to battery power, or want to transition your project to battery power, then you can put your Notecard into periodic mode with the following request using the in-browser terminal or directly in your firmware.

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{
 "req": "hub.set",
 "mode": "periodic",
 "outbound": 60,
 "inbound": 120
}