Impulses can be deployed as an optimized Syntiant NDP 101/120 library. This packages all your signal processing blocks, configuration and learning blocks up into a single package. You can include this package in your own application to run the impulse locally. In this tutorial you’ll export an impulse, and run the application on the Syntiant TinyML Board or Arduino Nicla Voice to control GPIO pins when the keyword ‘go’ or ‘stop’ is uttered, or if a circular motion is detected.

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Prerequisites

Make sure you followed the Keyword spotting - Syntiant - RC Commands or Motion recognition - Syntiant tutorial, have a trained impulse, and can load code on your board.
Naming your classesThe NDP chip expects one and only negative class and it should be the last in the list. For instance, if your original dataset looks like: yes, no, unknown, noise and you only want to detect the keyword ‘yes’ and ‘no’, merge the ‘unknown’ and ‘noise’ labels in a single class such as z_openset (we prefix it with ‘z’ in order to get this class last in the list).

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Exporting Syntiant library

Go to the Deployment page of your project and select the Syntiant library option for either NDP101 (Syntiant TinyML) or NDP120 (Arduino Nicla Voice):

Export to Syntiant NDP101 library for custom model development

Unzip the archive and copy the model-parameters content into the src/model-parameters/ folder of the firmware source code. The export also creates an ei_model synpkg or bin file that we will use later on to flash the board.

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Customizing and compiling the source code

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For Syntiant TinyML

You can add your custom logic to the main Arduino sketch by customizing the on_classification_changed() function. By default this function contains the following code to activate LEDs based on “stop” and “go” classes: 
void on_classification_changed(const char *event, float confidence, float anomaly_score) {

    // here you can write application code, e.g. to toggle LEDs based on keywords
    if (strcmp(event, "stop") == 0) {
        // Toggle LED
        digitalWrite(LED_RED, HIGH);
    }

    if (strcmp(event, "go") == 0) {
        // Toggle LED
        digitalWrite(LED_GREEN, HIGH);
    }
}

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For Arduino Nicla Voice

Open the src/ei_syntiant_ndp120.cpp file and look at the match_event() function. We can customize the code as follows to activate LEDs based on “stop” and “go” classes: 
static void match_event(char* label)
{
    if (_on_match_enabled == true){
        if (strlen(label) > 0) {
            got_match = true;
            ei_printf("Match: %s\n", label);
            if (strcmp(label, "go") == 0) {
              nicla::leds.setColor(green);
            }
            if (strcmp(label, "stop") == 0) {
              nicla::leds.setColor(red);
            }
        }
    }
}
You will also need to disable the default LED activation in the ei_main() function: 
if (got_match == true){
        got_match = false;
        // nicla::leds.setColor(blue); // => disable default color
        ThisThread::sleep_for(100);
        nicla::leds.setColor(off);
    }

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Compiling the source code

Once you’ve added your own logic, to compile and flash the firmware run:
  • Windows
    • update_libraries_windows.bat (Syntiant TinyML only)
    • arduino-win-build.bat --build for audio support (add --with-imu flag for IMU support)
    • arduino-win-build.bat --flash
  • Linux and Mac
    • ./arduino-build.sh --build for audio support (add --with-imu flag for IMU support)
    • ./arduino-build.sh --flash

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Deploying your impulse

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On Syntiant TinyML

Once you’ve compiled the Arduino firmware:
  • Take the .bin file output by Arduino and rename it to firmware.ino.bin.
  • Replace the firmware.ino.bin from our default firmware (our default firmware can be downloaded from here)
  • Replace the ei_model*.bin file in our default firmware by the one from the Syntiant library.
  • Launch the script for your OS to flash the board

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On Arduino Nicla Voice

Once you’ve compiled the Arduino firmware:
  • Take the .elf file output by Arduino and rename it to firmware.ino.elf.
  • Replace the firmware.ino.elf from our default firmware (our default firmware can be downloaded from here)
  • Replace the ei_model.synpkg file in our default firmware by the one from the Syntiant library.
  • Launch the script for your OS to flash the board
Great work! You’ve captured data, trained a model, and deployed it to your board. You can now control LEDs, activate actuators, or send a message to the cloud whenever you say a keyword or detect some motion!