Getting Started with OpenEL for Arduino

OpenEL(Open Embedded Library) is a unified API(Application Programming Interface) for actuators and sensors. The specifications and implementation have been developed by JASA(Japan Embedded Systems Technology Association) since 2011.

As of November 13, 2021, version 3.2.1 is available.

1. Supported Hardware

2. Install Arduino IDE

  1. See “Install the Arduino Desktop IDE” in the document, “Getting Started with Arduino products”.
  2. See “Using the Library Manager” in the document, “Installing Additional Arduino Libraries” and Install Blynk library.
  3. See the document, “Arduino IDE Development” and install USB driver, M5Stack boards and M5Stack library.

3. Install OpenEL for Arduino

  1. Download the .zip file( openel-arduino-3.2.1.zip ) from the GitHub repository “openel/openel-arduino”.
  2. Open Arduino IDE.
  3. See “Importing a .zip Library” in the document, “Installing Additional Arduino Libraries” and install OpenEL for Arduino.

4. How to use OpenEL for Arduino

  1. In Arduino IDE, navigate to File > Examples > OpenEL > BALA2
  2. Connect your M5Stack BALA2.
  3. Verify/Compile and Upload BALA2 sketch to your M5Stack BALA2.
    • You may also need python (version 3) and python-serial module if they are not already installed to your system.
    • For Ubuntu 20.04, run the next command to install them: sudo apt install python-is-python3 python3-serial
  4. You can see the Self-balancing Robot running slowly.

4.1 How to connect to BALA2 by using Blynk

  1. Sign Up Blynk and get your “Blynk Auth Token”.
  2. Write your token into the following line in BALA2.ino. 
    47 : #define AUTH "My Blynk Auth Token" // Your Blynk Auth Token
  3. Verify/Compile and Upload BALA2 sketch to your M5Stack BALA2.

  4. See the document, “Build your first IoT app in five minutes” and download and install Blynk(legacy) application to your Android or iPhone.

  5. Set up Joystick Settings in your Blynk(legacy) application. 
    OUTPUT
mode:MERGE
name:V0
[0]:from -1 to +1
[1]:from -1 to +1
AUTORETURN:ON
ROTATE ON TILT:ON
WRITE INTERVAL:100ms
  6. Connect to BALA2.
  7. Enjoy!

5. How to add a new device

  1. Apply to JASA for Device Kind ID(Only if you want to add a new kind of device) and Vendor ID assignment.
  2. Change to the OpenEL source directory, Arduino/libraries/openel-arduino-3.2.0/src
  3. Copy and Rename HAL Component file( openEL_Actuatorxxx.hpp and openEL_Actuatorxxx.cpp or openEL_Sensorxxx.hpp and openEL_Sensorxxx.cpp).
  4. File name naming convention is the following. DeviceName is required if the product has multiple devices of the same type.
openEL_[Device Kind][ProductName][DeviceName]

ex.
openEL_SensorM5StackGrayBMM150.cpp
openEL_SensorM5StackGrayBMM150.hpp
openEL_SensorM5StackGrayMPU6886.cpp
openEL_SensorM5StackGrayMPU6886.hpp
  1. Edit your HAL Component file.
  2. Add your header file and Hal Registration Table into openEL_registryConfig.cpp file.
  3. You can use your new device from your sketch by using deviceKindId, vendorId, productId, and instanceId.
ex.
  Actuator *motor_l = 0;
  Actuator *motor_r = 0;
  Sensor *IMU = 0;
  Sensor *BMM = 0;

  HALId halid1, halid2, halid3, halid4;
  halid1.deviceKindId = 0x1;  // Motor
  halid1.vendorId = 0xA;      // M5Stack
  halid1.productId = 0x1;     // BALA2
  halid1.instanceId = 0x1;    // Left Motor

  halid2.deviceKindId = 0x1;
  halid2.vendorId = 0xA;
  halid2.productId = 0x1;
  halid2.instanceId = 0x2;    // Right Motor

  halid3.deviceKindId = 0x2;  // Gyroscope Sensor
  halid3.vendorId = 0xA;
  halid3.productId = 0x1;
  halid3.instanceId = 0x1;

  halid4.deviceKindId = 0xD;  // Magnetic Sensor
  halid4.vendorId = 0xA;
  halid4.productId = 0x1;
  halid4.instanceId = 0x1;

  motor_l = new Actuator(halid1);
  motor_r = new Actuator(halid2);
  IMU = new Sensor(halid3);
  BMM = new Sensor(halid4);

6. How to Add your HAL Component file to repository

  1. Fork openel-arduino repository.
  2. Add and Commit your HAL Component file to your repository.
  3. Create a pull request.

We look forward to your pull request.