Tag Archives: Sense

The Arduino Nano 33 BLE Sense Sensor Library You Have Been Waiting For

Quick Links

The Arduino Nano 33 BLE Sense was released in July 2019 and was a real step up for Arduino! Using the Arm Cortex-M4F based nRF52840, the Nano 33 BLE’s arrival made the days of Atmel based 8-bit microcontrollers seem numbered. With the proliferation of dirt cheap Arduino clones this was probably the result of Arduino seeing the writing on the wall that keeping it simple was probably not going to bring in the dough anymore. In the end the sheer amounts of fairly useless Arduino projects seem a bit dull these days, and with more complex offerings such as the Nano 33 series, a new era of seriously cool projects may be on the horizon.

Previously in The Hacky Super Loop Arduino Nano 33 BLE Sense Example You Have Been Waiting For I attempted to address the lack of meaningful working examples for this board. The interfaces for each sensor are not always ideal, and no concrete examples are widely available that enable uses to utilise Mbed OS to gather sensor values.

The ability to use Mbed OS with Arduino is a real step up for Arduino. Finally, a reasonably performant and relatively deterministic way of arranging our more complex Arduino projects! In attempt to simplify the collection of sensor data and at the same time utilise the power of Mbed OS, Nano33BLESensor was born.

The Nano33BLESensor Library

Nano33BLESensor leverages Mbed OS to automatically place sensor measurements in a ring buffer that can be integrated into programs in a simple manner. This means Nano33BLESensor takes care of placing measurements in to the buffer “in the background”, and your program can retrieve them from the buffer at a later time when your program has time. It can be found on GitHub here. It can also be found using Arduino’s Library Manager, and available when searched for when using the Arduino IDE. Simple examples also exist to help get people started.

Nano33BLESensor Features

  • Class implementation with common interface for the following sensor measurements
    • 3-axis Accelerometer
    • 3-axis Gyroscope
    • 3-axis Magnetic
    • RMS Microphone
    • Barometric Pressure
    • Temperature (with humidity)
    • Proximity
    • RGBC Colour
    • Gesture
  • Mbed OS usage, allowing easy integration with programs.
  • Ring buffer usage, allowing the softening of time constraints in regard to the reading sensor measurements.
  • Excellent examples for all sensors designed for BLE and Serial Plotter that help you to get started.

In the end, the result of this is:

  • Super simple initialisation of on board sensors.
  • No code required beyond initialisation for collection of sensor data.
  • Super simple usage of sensor data.
  • Common interface among different sensors.
  • Using Mbed OS effectively makes the reading of sensor measurements happen “in the background”, and keeps it out of the main program loop.

Nano33BLESensor Examples

The Nano33BLESensor Library comes with a series of powerful examples that include sensor measurement data output using both Serial and Bluetooth. It is possible to view this data at the same time using Arduino’s Serial Plotter and a Bluetooth packet analysis tool such as Bluetooth LE Explorer. Some of the examples available on the GitHub repository are as follows:

Below are the results of a few of those examples.

Accelerometer Example

Gyroscope Example

Entire IMU Sensor Example

In order to view the data in a visually acceptable way, Bluetooth LE Explorer must be configured in a specific way. The below animation shows this setup.

How Nano33BLESensor Simplifies Sensor Usage

Here are a couple of examples of how Nano33BLESensor simplifies the collection of sensor data with the Nano 33 BLE Sense. For the full API, you can checkout the GitHub repository.

Initialising the on board accelerometer, reading data, and printing it.

Arduino_LSM9DS1

#include <Arduino_LSM9DS1.h>

float accelerometerX, accelerometerY, accelerometerZ;
void setup()
{
  IMU.begin()
}

void loop()
{
  if(IMU.accelerationAvailable())
  {
    IMU.readAcceleration(accelerometerX, accelerometerY, accelerometerZ);
    Serial.printf("%f,%f,%f\r\n", accelerometerX, accelerometerY, accelerometerZ);
  }
}

Nano33BLESensor

#include "Nano33BLEAccelerometer.h"

Nano33BLEAccelerometerData accelerometerData;
void setup()
{
  Accelerometer.begin()
}

void loop()
{ 
  if(Accelerometer.pop(accelerometerData))
  {
     Serial.printf("%f,%f,%f\r\n", accelerometerData.x, accelerometerData.y, accelerometerData.z);
  }
}

Initialising the on board colour sensor, reading data, and printing it.

Arduino_APDS9960

#include <Arduino_APDS9960.h>

int colourR, colourG, colourB, colourC;
void setup()
{
  APDS.setGestureSensitivity(50);
  APDS.begin();
  APDS.setLEDBoost(0);
}
void loop()
{
  if (APDS.colorAvailable())
  {
    APDS.readColor(colourR, colourG, colourB, colourC);
    Serial.printf("%d,%d,%d,%d\r\n", colourR, colourG, colourB, colourC);
  }
  delay(1000);
}

Nano33BLESensor

#include "Nano33BLEColour.h"

Nano33BLEColourData colourData;
void setup()
{
  Colour.begin()
}

void loop()
{ 
  if(Colour.pop(colourData))
  {
    Serial.printf( "%d,%d,%d,%d\r\n", colourData.r, colourData.g, colourData.b, colourData.c);
  }
}

Initialising the on board temperature sensor, reading data, and printing it

Arduino_HTS221

#include <Arduino_HTS221.h>

float temperature, humidity;
void setup()
{
  HTS.begin();
}
void loop()
{
  temperature = HTS.readTemperature();
  humidity = HTS.readHumidity();
  Serial.printf("%f, %f\r\n", temperature, humidity);
  delay(1000);
}

Arduino33BLESensor

#include "Nano33BLETemperature.h"

Nano33BLETemperatureData temperatureData;
void setup()
{
  Temperature.begin()
}

void loop()
{ 
  if(Temperature.pop(temperatureData))
  {
    Serial.printf("%f,%f\r\n", temperatureData.temperatureCelsius, temperatureData.humidity);
  }
}

Conclusion

Nano33BLESensor enables some interesting possibilities with the Nano 33 BLE. It simplifies the usage of onboard sensors by using a common interface, and leverages Mbed OS to allow the softening of time constraints in regard to the reading sensor measurements. It is hoped that this library will be useful to someone down the track!

The Hacky Super Loop Arduino Nano 33 BLE Sense Example You Have Been Waiting For

Update: For even better examples of the non-hacky variety, check out the Nano33BLESensor Library in The Arduino Nano 33 BLE Sense Sensor Library You Have Been Waiting For.

Quick Links

The Arduino Nano 33 BLE Sense was released in July 2019 and was a real step up for Arduino! Using the Arm Cortex-M4F based nRF52840, the Nano 33 BLE’s arrival made the days of Atmel based 8-bit microcontrollers seem numbered. With the proliferation of dirt cheap Arduino clones this was probably the result of Arduino seeing the writing on the wall that keeping it simple was probably not going to bring in the dough anymore. In the end the sheer amounts of fairly useless Arduino projects seem a bit dull these days, and with more complex offerings such as the Nano 33 series, a new era of seriously cool projects may be on the horizon.

A common complaint about the Nano 33 BLE Sense is the lack of working examples available for the board. Only a simple PDM Serial Plotter example exists when you install the board package, and this seems to have caused some confusion among users who were expecting an example to exist that uses all of the available on board sensors. In fact examples do exist for all the on board sensors, however they are available only on the individual sensor library repositories.

Below is a table including each sensor, it’s component name, a brief description, and a link to the example code.

SensorNameDescriptionExample Code Link
IMU LSM9DS1 3 acceleration channels, 3 angular rate channels, 3 magnetic field channels Arduino_LSM9DS1
Microphone MP34DT05PDM omnidirectional digital microphonePDM
IR APDS9960  Gesture, light, proximityArduino_APDS9960
Barometric Pressure LPS22HB  Barometric pressureArduino_LPS22HB
Temperature/Humidity HTS221  Temperature/Humidity Arduino_HTS221

Let’s Be Honest About What We Really Wanted

We wanted a super loop that would read all the values from the sensors and print them on the serial monitor/plotter. We wanted to be able to buy this board, fire it up, and to be able to look cool to all our friends immediately. We didn’t want to have to think. In fact we didn’t want to have to do anything. It did not matter that the actual values would probably be useless, we just wanted it to be there.

Perhaps the reason this super loop example we want is so terrible is because of the fact that the Nano 33 BLE Sense can utilise Mbed OS. Finally, a reasonably performant and relatively deterministic way of arranging our more complex Arduino projects! We can finally bid farewell to the almighty super loop!

Alas, I understand the RTOS can be a new and scary venture for some. And having just got my Nano 33 BLE sense, I decided to create a simple example program that can display all the available sensor data on serial plotter to check with the sensors are at least powered on and outputting semi-meaningful data without any of the BLE functionality.

The Example Project

The repository for nano-33-sense-serial-example can be found here. The data itself might be fairly useless for most applications, as it is mostly raw digital values pulled straight from the sensors which need to be converted to useful metrics before being meaningful. It plots the following raw data:

  • x/y/z acceleration data
  • x/y/z gyroscope data
  • x/y/z magnetic data
  • RMS microphone data
  • left/right/up/down gesture data
  • r/g/b light data
  • proximity data
  • Barometric pressure data
  • Temperature/Humidity data

Some of the difficulty in displaying this data in a coherent way is the different sampling frequencies in which sensor data is obtained. The table below shows these sampling frequencies.

Data TypeSampling Frequency
x/y/z acceleration data 109Hz
x/y/z gyroscope data 109Hz
x/y/z magnetic data 20Hz
16mS RMS microphone data 62.5Hz
left/right/up/down gesture data
Undefined
r/g/b light data
Undefined
proximity data
Undefined
Barometric pressure data
On request (1Hz in example)
Temperature/Humidity data On request (1Hz in example)

Because of this, all data is plotted with a frequency of 20Hz in an attempt to display the data in a way where the values will somewhat correlate to each other. There are some simple macro based configuration options available to allow some control over what data is actually outputted.

What the Output Looks Like

All Sensors

IMU Sensor

Gesture/Light/Proximity Sensor

Barometric Pressure Sensor

RMS Microphone Output

Temperature/Humidity Sensor

Conclusion

The nano-33-sense-serial-example is a great way to visualise all of the onboard sensors on the Nano 33 BLE sense. Since writing this example, I have largely replicated this project using Mbed OS in an effort to create a simple, low power alternative that can be used as the base for many projects that use the Nano 33 BLE sense. You can read about it in The Arduino Nano 33 BLE Sense Sensor Library You Have Been Waiting For.