Increase the sampling rate of Arduino Nano 33 BLE

Question

I'm using a Arduino Nano 33 BLE. In my project I have to send the accelerometer and gyroscope data via bluetooth to an android application. My sample rate is 10Hz but I should have 50Hz. How can I change Arduino Nano's sample rate?

thank you

Answer 1

So this will require bypassing the LSM9DS1 Arduino Library and manually utilizing Arduino's wired connection (See writeRegister() function in Arduino_LSM9DS1 class) to set the registers in the IMU.By default the sampling rate is 119Hz, so you will need to reduce it to 50Hz for your application (and for consistent reads).

For information regarding each register, the datasheet below contains all info over the IMU. https://www.st.com/resource/en/datasheet/lsm9ds1.pdf

To get a better understanding of how to adapt the existing IMU library for your needs, you can visit the GitHub link below for the current Arduino IMU library source code. https://github.com/arduino-libraries/Arduino_LSM9DS1

Look to the begin method for information on changing the sampling rate to suite your needs: https://github.com/arduino-libraries/Arduino_LSM9DS1/blob/7c8e9a0f8373a6e3ad1cd0f6ab0d66603a69f4f3/src/LSM9DS1.cpp#L50

For increasing your BLE throughput you could create a rotating (<23 byte) buffer that is being regularly populated with the IMU data and then transmitted. Utilizing the writeValue() function you can send the buffer in a single packet.

I also made a forum post about maximizing the board's RADIO throughput which may be helpful. However, its solution currently does not support protocols Android would recognize and would be overkill in your situation. It is located below. https://forum.arduino.cc/t/stream-binary-data-from-arduino-nano-33-ble-to-pc-via-ble/917206