SAMD21 ML Evaluation Kit Data Logger

Repository Overview

This repository contains firmware for streaming up to 6-axes IMU data over UART from one of the SAMD21 Machine Learning Evaluation Kits (SAM-IoT + MikroE IMU2/IMU14 Click Board); the project can be configured to build firmware for both the Bosch IMU and TDK IMU variants, streaming using one of several formats as described in the sections below.

Microchip Machine Learning Evaluation Kits

Hardware Used

• SAMD21 Machine Learning Evaluation Kit with Bosch BMI160 IMU (EV45Y33A)
• SAMD21 Machine Learning Evaluation Kit with TDK ICM42688 IMU (EV18H79A)

Software Used

• MPLAB® X IDE (https://microchip.com/mplab/mplab-x-ide)
• MPLAB® XC32 compiler (https://microchip.com/mplab/compilers)
• MPLAB® Harmony 3 (https://www.microchip.com/harmony)

Related Documentation

• ATSAMD21G18 Product Family Page
• SAM-IoT WG Development Board Product Details

How to Configure, Compile, and Flash

The steps below explain the process of configuring the the data logger firmware build, compiling it, and flashing it to the SAMD21 device.

1. Plug your SAMD21 evaluation kit into your PC via USB.

2. Install the MPLAB X IDE and XC32 compiler. These are required to load the data logger project and to program the SAMD21 board.

3. Open the firmware/samd21_iot_imu.X project folder in MPLAB X.

4. Select the appropriate MPLAB X Project Configuration for your sensor according to the table below.

   Sensor Type	MPLAB X Project Configuration Selection
   Bosch BMI160 IMU	SAMD21_IOT_WG_BMI160
   TDK ICM42688 IMU	SAMD21_IOT_WG_ICM42688

   Project configuration can be set in the MPLAB X toolbar drop down menu as shown in the image below

   MPLAB X Project Configuration Selection

5. Select the data streaming format you want by setting the DATA_STREAMER_FORMAT macro in firmware/src/app_config.h to the appropriate value as summarized in the table below.

   Streaming Format	app_config.h Configuration Value
   ASCII text	#define DATA_STREAMER_FORMAT DATA_STREAMER_FORMAT_ASCII
   MPLAB Data Visualizer stream	#define DATA_STREAMER_FORMAT DATA_STREAMER_FORMAT_MDV
   SensiML Simple Stream	#define DATA_STREAMER_FORMAT DATA_STREAMER_FORMAT_SMLSS

6. Modify high level sensor parameters like sample rate (SNSR_SAMPLE_RATE), accelerometer range (SNSR_ACCEL_RANGE), and others by changing the macro values defined in firmware/src/app_config.h. See the inline comments for further description.

7. Once you're satistfied with your configuration, click the Make and Program Device button in the toolbar (see image below for reference).

   Make and Program Device

Firmware Operation

The data streamer firmware will output sensor data over the UART port with the following UART settings:

• Baudrate 115200
• Data bits 8
• Stop bits 1
• Parity None

In addition, the onboard LEDs will indicate errors occurring in the firmware as summarized in the table below:

State	LED Behavior	Description
Error	Red (ERROR) LED lit	Fatal error. (Do you have the correct sensor plugged in?).
Buffer Overflow	Yellow (DATA) and Red (ERROR) LED lit for 5 seconds	Processing is not able to keep up with real-time; data buffer has been reset.

Usage with the MPLAB Data Visualizer and Machine Learning Plugins

This project can be used to generate firmware for streaming data to the MPLAB Data Visualizer plugin by setting the DATA_STREAMER_FORMAT macro to DATA_STREAMER_FORMAT_MDV as described above. Once the firmware is flashed, follow the steps below to set up Data Visualizer.

1. Connect the SAMD21 board to your computer, open up MPLAB X, and open the Data Visualizer plugin.
2. Click the Load Workspace button as highlighted in the image below. Select one of the workspace files included in this repository - located under the mplab-dv-workspaces folder - whose name most closely describes your sensor configuration; you can always modify the configuration once it is loaded if needed.

Loading the workspace file

3. Next, select the Serial/CDC Connection that corresponds to the SAMD21 board, adjust the baud rate to 115200, and click Apply.

Configuring the SAMD21 serial port

4. Use the play button on the Serial/CDC Connection to connect to the serial port. Once the connection is made, the SAMD21 will be available for use with the variable streamer.

Start Streaming

5. Switch to the Variable Streamers tab and select the aforementioned Serial/CDC Connection from the drop down menu as the input data source for the IMU variable streamer (see image below for reference); this will enable parsing of the SAMD21 data stream. You may delete or add variables here if your sensor configuration differs from the pre-loaded ones.

Variable streamer data source selection

The IMU data should now be available in the time plot. Double click anywhere within the time plot to start/stop scrolling of the time axis

Data Visualizer Time Plot

Visit the Machine Learning Plugin page to learn more about using the Data Visualizer plugin to export your data for machine learning applications.