Xsens MTi-3-DK Interface with Arduino MEGA

Introduction

This example code is tested between the Arduino MEGA R3 Board 2560 and the Xsens MTi-3-DK(Hardware version 3).

Interface

Arduino Mega	MTi-3-DK
3V3 Power	3V3(P101-4)
GND	GND(P101-6)
Digital Pin 3	DRDY(P102-4)
Digital Pin 5	RESET(P102-5)
SDA1	SDA(P100-9)
SCL1	SCL(P100-10)

or see this image:

Change the Bytes Limit of Arduino Library

The default Arduino library has limit on 32 bytes, that means you couldn’t get three types of data including acc, rateofturn, mag, which would be 48 bytes.

You could change the values in the Arduino library, by default it is at:

C:\Users\{YOUR_USER_NAME}\AppData\Local\Arduino15\packages\arduino\hardware\avr\1.8.6\libraries\Wire\src

Now you could change the Wire.h's value to:

#define BUFFER_LENGTH 64

And the utility\twi.h's value to:

  #define TWI_BUFFER_LENGTH 64

In this case, you could get data up to 64 bytes, and this could cover 4 types of float32 data(euler, acc, rateofturn, mag).

Change the Output Configuration

If you want to change the output, you could change the output_config_payload in the mt_application.cpp:

uint8_t data_rate = 1; //change this value to desired data
uint8_t output_config_payload[] = { 0x20, 0x30, 0x00, data_rate, 0x40, 0x20, 0x00, data_rate, 0x80, 0x20, 0x00, data_rate, 0xC0, 0x20, 0x00, data_rate };

For more information, please refer to:

• How to use Device Data View to learn MT Low Level Communications
• MT Low Level Communication Protocol Documentation

Please note that the allowed output bytes should be less equal than 64 bytes.

Change the address of the MTi

You could refer to the MTi-1 Series Datasheet, for example, if you want to change the address to 0x6A, you could connect the Arduino's GND to the MTi-3-DK's pin 100-6(ADD0).

Limitations of Arduino MEGA Board

• Serial.println could only print maximum 6 fractional numbers.
• double implementation is the same with float, see reference. Which means the FP16.32 format for the position/velocity, and the converted double precision UTC Time would be force back to Float32. If you are looking for higher precision, you might want to store the FP16.32 into two separate values for the integer and fractional parts, same with UTC Time.

Note for Arduino UNO

Tried this code in Arduino UNO, but the dynamic memory of UNO is so low, it is almost not possible to run, as an alternative, you could try this repo, but for this version, you would need to add the reset device code like the state management code in the MtApplication::handleEvent in the beginning, otherwise it wouldn't properly initialize sometimes.