MTi-3-8A7G6-DK - Xsens / Fairchild

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Document MT0512P.A

Data sheet MTi 1-series

Document MT0512P, Revision A, 8 Jul 2015

Features

 Full-featured AHRS on 12.1 x 12.1 mm module

 Roll/pitch accuracy (dynamic) 1.0 deg

 Heading accuracy 2.0 deg

 Minimal requirements on host processor

 Uniform interface over product lifetime

o No hardware/software interface changes

o No EOL

 Always best-in-class inertial sensors incorporated

 Industry-leading signal processing pipeline

(AttitudeEngineTM) with vibration-rejection

 Robust and accurate orientation algorithm

(XKF3TM)

 API-compatible with all Xsens’ Motion Trackers

o Drivers and examples on ARM® mbedTM

 Low power (45 mW @ 3.0V)

Applications

 Miniature aerial vehicles

 Heavy machinery/agriculture

 Robotics, pedestrian dead-reckoning

 Industrial grade VR/AR, HMD’s and handheld

devices

Related Resources

 www.xsens.com/MTi-1-series

 MTi 1-series DK User Manual (MT0513P)

 MT Low Level Communication Protocol

Documentation (MT0101P)

 MTi White Paper: Next generation Xsens Motion

Trackers for Industrial applications

Description

The MTi 1-series is a module outputting 3D orientation,

3D rate of turn, 3D accelerations, and 3D magnetic

field, depending on the product configuration. It is

available as an Inertial Measurement Unit (IMU),

Vertical Reference Unit (VRU) or Attitude and Heading

Reference System (AHRS).

This fully-functional self-contained module is easy to

design in with limited hardware components to be

added. The fully documented, industry-standard

communication protocol allows for customization of the

data message in terms of data, frequency and output

format. Signals are fully processed onboard, requiring

very little resources from the host and is very well suited

for applications in simple MCU-operated environments.

The host can read-out the data over SPI, I2C or UART.

With a roll/pitch accuracy of 1.0º RMS and yaw

accuracy of 2º RMS under dynamic conditions, the

output is excellent for control and stabilization of any

object and navigation of e.g. unmanned vehicles.

Figure 1: MTi 1-series

Product

Output

MTi-1

IMU

MTi-2

VRU

MTi-3

AHRS

Motion data

●

Magnetic field

●

Roll/pitch

●

Heading tracking

●

Referenced yaw

●

3D AHRS/VRU/IMU module

Data sheet MTi 1-series

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Document MT0512P.A

Data sheet MTi 1-series

Table of Contents

TABLE OF CONTENTS .................................................................................................................................................... 2

1 GENERAL INFORMATION .................................................................................................................................. 3

1.1 ORDERING INFORMATION .................................................................................................................................... 3

1.2 BLOCK DIAGRAM .............................................................................................................................................. 3

1.3 TYPICAL APPLICATION ......................................................................................................................................... 4

1.4 PIN CONFIGURATION .......................................................................................................................................... 4

1.5 PIN MAP ........................................................................................................................................................ 5

1.6 PIN DESCRIPTIONS ............................................................................................................................................. 6

1.7 PERIPHERAL INTERFACE SELECTION .......................................................................................................................... 6

1.7.1 I2C ..................................................................................................................................................... 7

1.7.2 SPI ..................................................................................................................................................... 7

1.7.3 UART half duplex ................................................................................................................................ 7

1.7.4 UART full duplex with RTS/CTS flow control ........................................................................................... 8

1.8 RECOMMENDED EXTERNAL COMPONENTS .................................................................................................................. 8

2 MTI 1-SERIES ARCHITECTURE............................................................................................................................. 9

2.1 MTI 1-SERIES CONFIGURATIONS ............................................................................................................................. 9

2.1.1 MTi-1 IMU ......................................................................................................................................... 9

2.1.2 MTi-2 VRU ......................................................................................................................................... 9

2.1.3 MTi-3 AHRS ........................................................................................................................................ 9

2.2 SIGNAL PROCESSING PIPELINE .............................................................................................................................. 10

2.2.1 Strapdown integration ...................................................................................................................... 10

2.2.2 XKF3TM Sensor Fusion Algorithm ......................................................................................................... 10

2.2.3 Frames of reference used in MTi 1-series ............................................................................................. 11

3 3D ORIENTATION AND PERFORMANCE SPECIFICATIONS ................................................................................... 12

3.1 3D ORIENTATION SPECIFICATIONS ......................................................................................................................... 12

3.2 SENSORS SPECIFICATIONS ................................................................................................................................... 12

4 SENSOR CALIBRATION .................................................................................................................................... 14

5 SYSTEM AND ELECTRICAL SPECIFICATIONS ....................................................................................................... 15

5.1 INTERFACE SPECIFICATIONS ................................................................................................................................. 15

5.2 SYSTEM SPECIFICATIONS .................................................................................................................................... 15

5.3 ELECTRICAL SPECIFICATIONS ................................................................................................................................ 16

5.4 ABSOLUTE MAXIMUM RATINGS ............................................................................................................................ 16

6 MTI 1-SERIES SETTINGS AND OUTPUTS ............................................................................................................ 17

6.1 MESSAGE STRUCTURE ....................................................................................................................................... 17

6.2 OUTPUT SETTINGS ........................................................................................................................................... 18

6.3 MTDATA2 ................................................................................................................................................... 19

6.4 SYNCHRONIZATION AND TIMING ........................................................................................................................... 20

7 MAGNETIC INTERFERENCE .............................................................................................................................. 21

7.1 MAGNETIC FIELD MAPPING ................................................................................................................................ 21

7.2 ACTIVE HEADING STABILIZATION (AHS).................................................................................................................. 21

8 PACKAGE AND HANDLING ............................................................................................................................... 22

8.1 PACKAGE DRAWING ......................................................................................................................................... 22

8.2 PACKAGING .................................................................................................................................................. 23

8.3 REFLOW SPECIFICATION ..................................................................................................................................... 23

9 TRADEMARKS AND REVISIONS ........................................................................................................................ 24

9.1 TRADEMARKS ................................................................................................................................................ 24

9.2 REVISIONS .................................................................................................................................................... 24

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Document MT0512P.A

Data sheet MTi 1-series

1 General information

1.1 Ordering Information

Part Number

Output

Package

Packing

Method

MTi-1-8A7G6

IMU; inertial data

PCB, JEDEC-PLCC-28 compatible

Tray, MOQ: 20

MTi-2-8A7G6-TR20

VRU; inertial data, roll/pitch

(referenced), yaw (unreferenced)

PCB, JEDEC-PLCC-28 compatible

Tray, MOQ: 20

MTi-3-8A7G6-TR20

AHRS; inertial data, roll/pitch/yaw

PCB, JEDEC-PLCC-28 compatible

Tray, MOQ: 20

MTi-3-8A7G6-DK

Development kit for MTi 1-series,

including MTi-3-8A7G6

Single unit

Other packaging methods available on request (>1k units). Contact Xsens for more information.

1.2 Block Diagram

Figure 2: MTi 1-series module block diagram

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Document MT0512P.A

Data sheet MTi 1-series

1.3 Typical Application

1.4 Pin Configuration

Figure 4: Pin assignment

Figure 3: Typical application

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Document MT0512P.A

Data sheet MTi 1-series

1.5 Pin map

The pin map depends on the peripheral selection. See section 1.7 on how to set the peripherals.

PSEL:

I2C

PSEL:

SPI

PSEL:

UART half duplex

PSEL:

UART full duplex

DNC

GND

VDD

nRST

VDDIO

GND

DNC

SPI_DNCS

DNC

ADD21

SPI_MOSI

DNC

ADD1

SPI_MISO

DNC

ADD0

SPI_SCK

DNC

GND

PSEL0

PSEL1

SYNC_IN

DNC

RTS

DRDY

DNC

nRE

CTS2

I2C_SDA

DNC

UART_RX

I2C_SCL

DNC

UART_TX

GND

DNC

I2C addresses, see Table 2: List of I2C addresses

CTS cannot be left unconnected if the interface is set to UART full duplex. If HW flow control is not used, connect to

GND.

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Document MT0512P.A

Data sheet MTi 1-series

1.6 Pin Descriptions

Name

Type

Description

Power Interface

VDD

Power

Power supply voltage for sensing elements

VDDIO

Power

Digital I/O supply voltage

Controls

PSEL0

Selection pins

These pins determine the signal interface. See table below. Note that when the

PSEL0/PSEL1 is not connected, its value is 1. When PSEL0/PSEL1 is connected

to GND, its value is 0

PSEL1

nRST

Active low reset pin, connect to VDDIO if not used

ADD2

Selection pins

I2C address selection lines

ADD1

ADD0

Signal Interface

I2C_SDA

I2C interface

I2C serial data

I2C_SCL

I2C serial clock

SPI_nCS

SPI interface

SPI chip select

SPI_MOSI

SPI serial data input (slave)

SPI_MISO

SPI serial data output (slave)

SPI_SCK

SPI serial clock

RTS

UART

interface

Hardware flow control in UART full duplex mode (Ready-to-Send)

CTS

Hardware flow control in UART full duplex mode (Clear-to-Send)

nRE

Receiver control signal in UART half duplex mode

Transmitter control signal in UART half duplex mode

UART_RX

Receiver data input

UART_TX

Transmitter data output

SYNC_IN

Sync interface

SYNC_IN accepts a trigger which has the following functionality, depending on the

configuration set in the firmware

- It sends out the latest available data message, or

- It adjusts the bias of the clock onboard the MTi

DRDY

Data ready

Data ready pin indicates that data is available (SPI / I2C)

1.7 Peripheral interface selection

The MTi 1-series modules have four modes of peripheral interfacing. Only one mode can be used simultaneously and

is determined by the state of peripheral selection pins PSEL0 and PSEL1 at startup. Table 1 specifies how the PSEL

lines select the peripheral interface. Note that the module has internal pull-ups. Not connecting PSEL results in a

value of 1, connecting PSEL to a GND results in a value of 0.

Table 1. Peripheral interface selection

Interface

PSEL0

PSEL1

I2C

SPI

UART half-duplex

UART full-duplex

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Document MT0512P.A

Data sheet MTi 1-series

1.7.1 I2C

The MTi 1-series module can be configured to act as an I2C slave. The slave address is determined by the ADD0,

ADD1 and ADD2 pins. These pins are pulled-up internally so when left unconnected the address selection defaults to

ADD[0..2] = 111.

Further specifications TBC, available from November 2015.

Table 2. List of I2C addresses

I2C address

ADD0

ADD1

ADD2

0x1D

0x1E

0x28

0x29

0x68

0x69

0x6A

0x6B (default)

1.7.2 SPI

The MTi 1-series module can be configured to act as an SPI slave. Detailed specifications TBC, available from

November 2015.

1.7.3 UART half duplex

The MTi 1-series module can be configured to communicate over UART in half duplex mode. The UART frame

configuration is 8 data bits, no parity and 1 stop bit (8N1). In addition to the RX and TX pins the control lines nRE and

DE are used. These control outputs are used to drive the TX signal on a shared medium and to drive the signal of the

shared medium on the RX signal.

A typical use case for this mode is to directly drive a RS485 transceiver where the shared medium is the RS485 signal

and nRE and DE lines control the buffers inside the transceiver.

When the MTi is transmitting data on its TX pin it will raise both the nRE and DE lines, else it will pull these lines low.

Figure 5 Behaviour of the nRE and DE lines

Note that in this mode the UART of the MTi 1-series itself is still operating full duplex.

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Document MT0512P.A

Data sheet MTi 1-series

1.7.4 UART full duplex with RTS/CTS flow control

The MTi 1-series module can be configured to communicate over UART in full duplex mode with RTS/CTS flow

control. The UART frame configuration is 8 data bits, no parity and 1 stop bit (8N1). In addition to the RX and TX

signals for data communication the RTS and CTS signals are used for hardware flow control.

The CTS signal is an input for the MTi. The MTi checks the state of the CTS line at the start of every byte it transmits.

If CTS is low the byte will be transmitted. Otherwise transmission is postponed until CTS is lowered. When during the

transmission of a byte the CTS signal is raised then the transmission of that byte is completed before postponing

further output. This byte will not be retransmitted. This behaviour is shown in the following image:

Figure 6 Data transmit behaviour under CTS

The RTS signal is an output for the MTi. If the RTS line is high, the MTi is busy and unable to receive new data.

Otherwise the MTi1’s UART is idle and ready to receive. After receiving a byte the DMA controller of the MTi will

transfer the byte to its receive FIFO. The RTS signal will be asserted during this transfer. So with every byte received

the RTS line is raised shortly like shown in the following image:

Figure 7 RTS behaviour under data reception

This communication mode can be used without hardware flow control. In this case the CTS line needs to be tied low

(GND) to make the MTi transmit.

1.8 Recommended external components

Component

Description

Typical value

Rpu

I2C pull-up resistor

2.7 kΩ

RPSEL0 / RPSEL1

Interface selection resistors

Up to 5kΩ

Notes:

- Rpu is only needed when the MTi-1 is configured for I2C interface

- RPSEL is only required when interface is not I2C. If the interface does not need to be switched, RPSEL0 and

RPSEL1 can be connected directly to GND.

Figure 8: External components (I2C interface) Figure 9: External components (UART interface)

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Document MT0512P.A

Data sheet MTi 1-series

2 MTi 1-series architecture

This section discusses the MTi 1-series architecture

including the various configurations and the signal

processing pipeline.

2.1 MTi 1-series configurations

The MTi 1-series is a fully-tested self-contained

module that can 3D output orientation data (Euler

angles (roll, pitch, yaw), rotation matrix (DCM) and

quaternions), orientation and velocity increments (∆q

and ∆v) and sensors data (acceleration, rate of turn,

magnetic field). The MTi 1-series module is available

as an Inertial Measurement Unit (IMU), Vertical

Reference Unit (VRU) and Attitude and Heading

Reference System (AHRS). Depending on the

product, output options may be limited to sensors data

and/or unreferenced yaw.

All MTi’s feature a 3D accelerometer/gyroscope

combo-sensor, a magnetometer, a high-accuracy

crystal and a low-power MCU. The MCU coordinates

the synchronization and timing of the various sensors,

it applies calibration models (e.g. temperature

modules) and output settings and runs the sensor

fusion algorithm. The MCU also generates output

messages according to the proprietary XBus

communication protocol. The messages and the data

output are fully configurable, so that the MTi 1-series

limits the load, and thus power consumption, on the

application processor.

2.1.1 MTi-1 IMU

The MTi-1 module is an Inertial Measurement Unit

(IMU) that outputs 3D rate of turn, 3D acceleration and

3D magnetic field. The MTi-1 also outputs coning and

sculling compensated orientation increments and

velocity increments (∆q and ∆v) from its

AttitudeEngineTM. Advantages over a gyroscope-

accelerometer combo-sensor are the inclusion of

synchronized magnetic field data, on-board signal

processing and the easy-to-use communication

protocol. Moreover, the testing and calibration

performed by Xsens result in a robust and reliable

sensor module, that can be integrated within a short

time frame. The signal processing pipeline and the

suite of output options allow access to the highest

possible accuracy at any bandwidth, limiting the load

on the application processor.

2.1.2 MTi-2 VRU

The MTi-2 is a 3D vertical reference unit (VRU). Its

orientation algorithm (XKF3TM) outputs 3D orientation

data with respect to a gravity referenced frame: drift-

free roll, pitch and unreferenced yaw. In addition, it

outputs calibrated sensor data: 3D acceleration, 3D

rate of turn and 3D earth-magnetic field data. All

modules of the MTi 1-series are also capable of

outputting data generated by the strapdown

integration algorithm (the AttitudeEngineTM outputting

orientation and velocity increments ∆q and ∆v). The

3D acceleration is also available as so-called free

acceleration which has gravity subtracted. Although

the yaw is unreferenced, though still superior to

gyroscope integration. With the feature Active

Heading Stabilization (AHS, see section 7.2) the drift

in unreferenced yaw can be limited to 1 deg after 60

minutes, even in magnetically disturbed environments.

2.1.3 MTi-3 AHRS

The MTi-3 supports all features of the MTi-1 and MTi-

2, and in addition is a full gyro-enhanced Attitude and

Heading Reference System (AHRS). It outputs drift-

free roll, pitch and true/magnetic North referenced yaw

and sensors data: 3D acceleration, 3D rate of turn, as

well as 3D orientation and velocity increments (∆q and

∆v), and 3D earth-magnetic field data. Free

acceleration is also available for the MTi-3 AHRS.

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Document MT0512P.A

Data sheet MTi 1-series

2.2 Signal processing pipeline

The MTi 1-series is a self-contained module, so all

calculations and processes such as sampling, coning

and sculling compensation and the Xsens XKF3TM

sensor fusion algorithm run on board.

2.2.1 Strapdown integration

The Xsens optimized strapdown algorithm

(AttitudeEngineTM) performs high-speed dead-

reckoning calculations at 1 kHz allowing accurate

capture of high frequency motions. This approach

ensures a high bandwidth. Orientation and velocity

increments are calculated with full coning and sculling

compensation. At an output data rate of up to 100 Hz,

no information is lost, yet the output data rate can be

configured low enough for systems with limited

communication bandwidth. These orientation and

velocity increments are suitable for any 3D motion

tracking algorithm. Increments are internally time-

synchronized with the magnetometer data.

2.2.2 XKF3TM Sensor Fusion Algorithm

XKF3 is a sensor fusion algorithm, based on Extended

Kalman Filter framework that uses 3D inertial sensor

data (orientation and velocity increments) and 3D

magnetometer, also known as ‘9D’ to optimally

estimate 3D orientation with respect to an Earth fixed

frame.

XKF3 takes the orientation and velocity increments

together with the magnetic field updates and fuses this

to produce a stable orientation (roll, pitch and yaw)

with respect to the earth fixed frame.

The XKF3 sensor fusion algorithm can be processed

with filter profiles. These filter profiles contain

predefined filter parameter settings suitable for

different user application scenarios.

The following filter profiles are available:

 General – suitable for most applications.

Supported by the MTi-3 module.

 Dynamic – assumes that the motion is highly

dynamic. Supported by the MTi-3 module.

 High_mag_dep – heading corrections rely

on the magnetic field measured. To be used

when magnetic field is homogeneous.

Supported by the MTi-3 module.

 Low_mag_dep – heading corrections are

less dependent on the magnetic field

measured. Heading is still based on

magnetic field, but more distortions are

expected with less trust being placed on

magnetic measurements. Supported by the

MTi-3 module.

 VRU_general – Roll and pitch are the

referenced to the vertical (gravity), yaw is

determined by stabilized dead-reckoning,

referred to as Active Heading Stabilization

(AHS) which significantly reduces heading

drift, see also section 7.2. Consider using

VRU_general in environments that have a

heavily disturbed magnetic field. The

VRU_general filter profile is the only filter

profile available for the MTi-2-VRU, also

supported by the MTi-3 module

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Document MT0512P.A

Data sheet MTi 1-series

2.2.3 Frames of reference used in MTi 1-series

The MTi 1-series module uses a right-handed coordinate system as the basis of the sensor of frame.

The following data is outputted in corresponding reference coordinate systems:

Data

Symbol

Reference coordinate system

Acceleration

ax, ay, az

Sensor-fixed

Rate of turn

ωx, ωy, ωz

Sensor-fixed

Magnetic field

mx, my, mz

Sensor-fixed

Free acceleration

ax, ay, az

Local Tangent Plane (LTP), default ENU

Velocity increment

∆vx, ∆vy, ∆vz

Local Tangent Plane (LTP), default ENU

Orientation increment

∆q0, ∆q1, ∆q2, ∆q3

Local Tangent Plane (LTP), default ENU

Orientation

Euler angles, quaternions or rotation matrix

Local Tangent Plane (LTP), default ENU

Local Tangent Plane (LTP) is a local linearization of the Ellipsoidal Coordinates (Latitude, Longitude, Altitude) in the

WGS-84 Ellipsoid.

It is straightforward to apply a rotation matrix to the MTi, so that the velocity and orientation increments, free

acceleration and the orientation output is output using that coordinate frame. The default reference coordinate system

is East-North-Up (ENU) and the MTi 1-series has predefined output options for North-East-Down (NED) and North-

West-Up (NWU). Any arbitrary alignment can be entered. These orientation resets have effect on all outputs that are

by default outputted with an ENU reference coordinate system.

Figure 10: Default sensor fixed coordinate system for the MTi 1-series module

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Data sheet MTi 1-series

3 3D Orientation and performance specifications

3.1 3D Orientation specifications

Table 3. Orientation specifications

Parameter

Typ

Unit

Comments

Roll/pitch

Static

0.75

deg

Dynamic

1.0

deg

Yaw

(heading)

Static/dynamic,

Magnetic field referenced

2.0

deg

MTi-3 AHRS only in a homogenous magnetic field

and a filter profile using magnetic field as

reference.

VRU_general filter profile

(unreferenced yaw)

deg after

60 min

Active Heading Stabilization (AHS) feature. See

section 7.2 for more information.

Output data rate

0-100

Accuracy and latency independent of output data

rate. Output data rate may be any integer divider

of 100 Hz or may be triggered by an external

pulse (SYNC_IN)

3.2 Sensors specifications

Table 4. Gyroscope specifications

Parameter

Min

Typ

Max

Unit

Comments

Full range

±2000

deg/s

Non-linearity

0.1

% of FS

Sensitivity variation

0.05

Over temperature range

Noise density

0.01

º/s/√Hz

g-sensitivity

0.001

deg/s/g

In-run bias stability

deg/h

Zero-rate output

±0.1

deg/s

Bias variation after calibration, bias is

continuously estimated by XKF3i

Bias repeatability (1 yr)

0.5

deg/s

The bias is continuously estimated by XKF3i.

Bandwidth

180

Natural frequency

kHz

This is the resonating frequency of the mass

in the gyro. The higher the frequency, the

higher the accuracy.

Table 5. Accelerometers specifications

Parameter

Min

Typ

Max

Unit

Comments

Full range

±16

Non-linearity

0.5

% of FS

Sensitivity variation

0.05

Over temperature range

Noise density

200

μg/√Hz

Zero-g output

±2

In-run bias stability

0.1

Bandwidth

180

As Xsens continues to update the sensors on the module, these specifications may change

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Document MT0512P.A

Data sheet MTi 1-series

Table 6. Magnetometer specifications

Parameter

Min

Typ

Max

Unit

Comments

Full range

±1.9

Gauss

Non-linearity

0.1

% of FS

Noise density

200

μG/√Hz

Table 7. Alignment specifications

Parameter

Typ

Unit

Comments

Non-orthogonality

(accelerometer)

0.05

deg

Non-orthogonality

(gyroscope)

0.05

deg

Non-orthogonality

(magnetometer)

0.05

deg

Alignment (gyr to acc)

0.05

deg

Alignment (mag to acc)

0.1

deg

Alignment of acc to the

module board

0.2

deg

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Document MT0512P.A

Data sheet MTi 1-series

4 Sensor calibration

Each MTi is individually calibrated and tested over its temperature range. The (simplified) sensor model of the

gyroscopes, accelerometers and magnetometers can be represented as following:

  

󰇛  󰇜

s = sensor data of the gyroscopes, accelerometers and magnetometers in rad/s, m/s2 or a.u. respectively

KT-1 = gain and misalignment matrix (temperature compensated)

u = sensor value before calibration (unsigned 16-bit integers from the sensor)

bT = bias (temperature compensated)

Xsens’ calibration procedure calibrates for many parameters, including bias (offset), alignment of the sensors with

respect to the module PCB and each other and gain (scale factor). All calibration values are temperature dependent

and temperature calibrated. The calibration values are stored in non-volatile memory in the MTi.

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Document MT0512P.A

Data sheet MTi 1-series

5 System and electrical specifications

5.1 Interface specifications

Table 8. Communication interfaces

Interface

Min

Typ

Max

Units

I2C

Host I2C interface

speed

400

kHz

SPI

Host SPI

Interface speed

MHz

Clock duty cycle

UART

Baudrates

921.6

4000

kbps

Table 9. Auxiliary interfaces

Interface

Min

Max

Unit

Comments

SYNC_IN

VIL

0.3 * VDDIO

Digital input voltage

VIH

0.45 * VDDIO + 0.3

Digital input voltage

VHYS

0.45 * VDDIO + 0.3

nRST

VIL

0.3 * VDDIO

Digital input voltage

VIH

0.45 * VDDIO + 0.3

Digital input voltage

VHYS

0.45 * VDDIO + 0.3

Generated reset

pulse duration

µs

5.2 System specifications

Table 10. System specifications

Interface

Min

Typ

Max

Comments

Size

Width/Length

12.0

12.1

12.2

PLCC-28 compatible

Height

2.45

2.55

2.65

Weight

0.66

gram

Temperature

Operating temperature

-40

+85

ºC

Ambient temperature, non-

condensing

Specified performance

operating temperature

+60

ºC

Power consumption

VDD 3.0V; VDDIO 1.8V

Timing accuracy

ppm

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Document MT0512P.A

Data sheet MTi 1-series

5.3 Electrical specifications

Table 11. Electrical specifications

Min

Typ

Max

Unit

Comments

VDD

2.16

3.45

VDDIO

1.8

VDD

VIL

0.3 * VDDIO

Digital input voltage

VIH

0.45 * VDDIO +

0.3

Digital input voltage

VHYS

0.45 * VDDIO +

0.3

Digital input voltage

VOL

0.4

Digital output voltage

VOH

VDDIO - 0.4

Digital output voltage

5.4 Absolute maximum ratings

Min

Max

Unit

Comments

Storage temperature

-40

+125

ºC

Operating temperature

-40

+85

ºC

VDD

0.3

4.0

VDDIO

0.3

VDD + 0.5

Acceleration 4

10,000

Any axis, unpowered, for 0.2 ms

ESD protection5

±2000

Human body model

This is a mechanical shock (g) sensitive device. Proper handling is required to prevent damage to the part.

This is an ESD-sensitive device. Proper handling is required to prevent damage to the part.

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Document MT0512P.A

Data sheet MTi 1-series

6 MTi 1-series settings and outputs

The MTi 1-series module uses the Xsens-proprietary Xbus protocol, which is compatible with all Xsens Motion Tracker

products.

6.1 Message structure

The communication with the MT is done by messages which are built according to a standard structure. The message

has two basic structures; one with a standard length and one with extended length. The standard length message has

a maximum of 254 data bytes and is used most frequently. In some cases the extended length message needs to be

used if the number of data bytes exceeds 254 bytes.

An MT message (standard length) contains the following fields:

Xbus header

Preamble

BID

MID

LEN

DATA

CHECKSUM

An MT message (extended length) contains these fields:

Preamble

BID

MID

LENext

LEN

DATA

CHECKSUM

Details on the Xbus protocol message structure can be found in the MT Low Level Communication Protocol

documentation (LLCP).

Field

Field width

Description

Preamble

1 byte

Indicator of start of packet  250 (0xFA)

BID

1 byte

Bus identifier or Address  255 (0xFF)

MID

1 byte

Message identifier

LEN

1 byte

For standard length message:

Value equals number of bytes in DATA field.

Maximum value is 254 (0xFE)

For extended length message:

Field value is always 255 (0xFF)

EXT LEN

2 bytes

16 bit value representing the number of data bytes for

extended length messages. Maximum value is 2048

(0x0800)

IND ID

1 byte

The type of indication received

DATA

(standard length)

0 – 254 bytes

Data bytes (optional)

DATA

(extended length)

255 – 2048 bytes

Data bytes

Checksum

1 byte

Checksum of message

www.xsens.com

Document MT0512P.A

Data sheet MTi 1-series

6.2 Output settings

The section below only describes the most important set of MTData2 data messages. For all messages supported by

the MTi 1-series, refer to the MT Low Level Communication Protocol documentation (LLCP).

The Output Configuration message sets the output of the device. Each data message has a DataID which consists of

a data type and a number format. The table below shows the most important MTData2 Data identifiers. The message

SetOutputconfiguration holds the DataID and the output frequency.

SetOutputConfiguration

MID 192 (0xC0)

DATA OutputConfig (N*4 bytes)

Set the output configuration of the device.

The data is a list of maximum 32 data identifiers combined with a desired output frequency. The response

message contains a list with the same format, but with the values actually used by the device.

Each entry in the list contains:

Offset

Value

Data Identifier (2 bytes)

Output frequency (2 bytes)

Group Name

Type Name

XDA type name6

Hex Value

Timestamp

XDI_TimestampGroup

Packet Counter

XDI_PacketCounter

1020

Sample Time Fine

XDI_SampleTimeFine

1060

Orientation Data

XDI_OrientationGroup

Quaternion

XDI_Quaternion

201y

Rotation Matrix

XDI_RotationMatrix

202y

Euler Angles

XDI_EulerAngles

203y

Acceleration

XDI_AccelerationGroup

Delta V (dv)

XDI_DeltaV

401y

Acceleration

XDI_Acceleration

402y

Free Acceleration

XDI_FreeAcceleration

403y

Angular Velocity

XDI_AngularVelocityGroup

Rate of Turn

XDI_RateOfTurn

802y

Delta Q (dq)

XDI_DeltaQ

803y

Magnetic

XDI_MagneticGroup

Magnetic Field

XDI_MagneticField

C02y

Status

XDI_StatusGroup

Status Word

XDI_StatusWord

E020

y: The hex value of the Format bits (see table below). The value is formed by doing a bitwise OR of the

available fields

XDA: Xsens Device API. Communication protocol in C, to be used on external processors.

www.xsens.com

Document MT0512P.A

Data sheet MTi 1-series

Field

Format

Description

Short name

Precision

0x0

Single precision IEEE 32-bit floating point number

Float32

0x1

Fixed point 12.20 32-bit number

Fp1220

0x2

Fixed point 16.32 48-bit number

Fp1632

0x3

Double precision IEEE 64-bit floating point number

Float64

Coordinate system

0x0

East-North-Up coordinate system

ENU

0x4

North-East-Down coordinate system

NED

0x8

North-West-Up

NWU

Example: the DataID for quaternions in NED coordinate system with fixed point 16.32 number format is represented

as 0x2016.

6.3 MTData2

Data is represented in the MTData2 message.

MTData2

MID 54 (0x36)

DATA DATA (length variable)

The MTData2 message contains output data according the current OutputConfiguration. An MTData2

message consists of one or more packets, each containing a specific output. The layout of an MTData2

message is shown below:

XBus

header

Packet #1

Packet #2

Packet #N

…

Xbus Header

Pre-

amble

BID

MID

LEN

DataID

Data LEN

Packet Data (Data LEN bytes)

0xFA

0xFF

0x36

An example data message is depicted below (explanation of the message, divided into parts, in the table):

FA FF 36 35 10 20 02 51 BC 10 60 04 00 21 49 AF 40 10 0C 39 B9 D8 00 B7 DD 80 00 3C C9 26 98 80 30 10 3F 80

00 01 B6 ED 60 01 36 94 A0 00 36 1E 60 00 E0 20 04 00 00 00 87 A0

Part of message (0x)

Meaning

FA FF 36 35

Xbus Header with total length of message (0x35)

10 20 02 51 BC

DataID 0x1020 (Packet counter), length 0x02, data (0x51 BC)

10 60 04 00 21 49 AF

DataID 0x1060 (Sample Time fine), length 0x04, data

40 10 0C 39 B9 D8 00 B7 DD 80 00 3C C9 26 98

DataID 0x4010 (velocity increment), length 0x0C, data

80 30 10 3F 80 00 01 B6 ED 60 01 36 94 A0 00

36 1E 60 00

DataID 0x8030 (orientation increment), length 0x10, data

E0 20 04 00 00 00 87

DataID 0xE020 (StatusWord), length 0x04, data

Checksum

www.xsens.com

Document MT0512P.A

Data sheet MTi 1-series

6.4 Synchronization and timing

The MTi 1-series modules can easily be synchronized with other sensors or sensor systems. The MTi accepts a pulse

and can then transmit the latest available data. This SYNC_IN functionality does not influence the accuracy of the

data as internally the MTi 1-series keeps estimating the orientation at its maximum frequency. Acceleration data and

rate of turn data is also outputted with the shortest possible latency.

The Sync Settings are set with the SetSyncSettings message:

SetSyncSettings

MID 44 (0x2C)

DATA Setting List (N*12 bytes)

Set the synchronization settings of the device.

Settings

Each setting describes either a system event that should trigger a sync in event that should trigger a system action.

SYNC_IN setting

Offset

(bytes)

Setting

Size

(bytes)

Description

Function

Value 8: Send Latest

Line

Value 2: SYNC_IN

Polarity

Which line transition to respond to. One of: Rising

Edge (1), Falling Edge (2) or Both (3)

Ignored for MTi 1-series

Skip First

The number of initial events to skip before taking

action.

Skip Factor

The number of events to skip after taking the

action before taking action again.

Ignored for MTi 1-series

Delay or Clock

period

Delay after receiving a sync pulse to taking action

(100μs units, range [0..60000])

www.xsens.com

Document MT0512P.A

Data sheet MTi 1-series

7 Magnetic interference

Magnetic interference can be a major source of error

for the heading accuracy of any Attitude and Heading

Reference System (AHRS). As an AHRS uses the

magnetic field to reference the dead-reckoned

orientation on the horizontal plane with respect to the

(magnetic) North, a severe and prolonged distortion in

that magnetic field will cause the magnetic reference

to be inaccurate. The MTi 1-series module has several

ways to cope with these distortions to minimize the

effect on the estimated orientation.

7.1 Magnetic Field Mapping

When the distortion is deterministic, i.e. when the

distortion moves with the MTi, the MTi can be

calibrated for this distortion this type of errors are

usually referred to as soft and hard iron distortions.

The Magnetic Field Mapping procedure compensates

for both hard-iron and soft-iron distortions.

In short, the magnetic field mapping (calibration) is

performed by moving the MTi together with the

object/platform that is causing the distortion. On an

external computer (Windows or Linux), the results are

processed and the updated magnetic field calibration

values are written to the non-volatile memory of the

MTi 1-series module. The magnetic field mapping

procedure is extensively documented in the Magnetic

Field Mapper User Manual (MT0202P), available in

the MT Software Suite.

7.2 Active Heading Stabilization (AHS)

It is often not possible or desirable to connect the MTi

1-series module to a high-level processor/host

system, so that the Magnetic Field Mapping procedure

is not an option. Also, when the distortion is non-

deterministic the Magnetic Field Mapping procedure

does not yield the desired result. For all these

situations, the on-board XKF3 sensor fusion algorithm

has integrated an algorithm called Active Heading

Stabilization (AHS).

The AHS algorithm delivers excellent heading tracking

accuracy. Heading tracking drift in the MTi 1-series

can be as low as 1 deg per hour, while being fully

immune to magnetic distortions.

AHS is only available in the VRU_general filter profile.

This filter profile is the only filter profile in the MTi-2

VRU and one of the 5 available filter profiles in the

MTi-3 AHRS.

www.xsens.com

Document MT0512P.A

Data sheet MTi 1-series

8 Package and handling

Note that this is a mechanical shock (g) sensitive device. Proper handling is required to prevent damage to the part.

Note that this is an ESD-sensitive device. Proper handling is required to prevent damage to the part.

8.1 Package drawing

The MTi 1-series module is compatible with JEDEC PLCC28 IC-sockets.

Figure 11: General tolerances are +/- 0.1 mm

Figure 12: Recommended MTi 1-series module footprint

www.xsens.com

Document MT0512P.A

Data sheet MTi 1-series

8.2 Packaging

The MTi 1-series module is shipped in trays. Trays are available with a MOQ of 20 modules. A full tray contains 152

modules.

Figure 13: A tray containing 20 MTi 1-series modules

8.3 Reflow specification

The moisture sensitivity level of the MTi 1-series modules corresponds to JEDEC MSL Level 3, see also:

 IPC/JEDEC J-STD-020E “Joint Industry Standard: Moisture/Reflow Sensitivity Classification for non-

hermetic Solid State Surface Mount Devices”

 IPC/JEDEC J-STD-033C “Joint Industry Standard: Handling, Packing, Shipping and Use of Moisture/Reflow

Sensitive Surface Mount Devices”.

The sensor fulfils the lead-free soldering requirements of the above-mentioned IPC/JEDEC standard, i.e. reflow

soldering with a peak temperature up to 260°C. Recommended Preheat Area (ts) is 80-100 sec. The minimum height

of the solder after reflow shall be at least 50µm. This is required for good mechanical decoupling between the MTi 1-

series module and the printed circuit board (PCB) it is mounted on. Assembled PCB’s may NOT be cleaned with

ultrasonic cleaning.

www.xsens.com

Document MT0512P.A

Data sheet MTi 1-series

9 Trademarks and revisions

9.1 Trademarks

notice. Xsens, MVN, MotionGrid, MTi, MTi-G, MTx, MTw, Awinda and KiC are registered trademarks or trademarks of

Xsens Technologies B.V. and/or its parent, subsidiaries and/or affiliates in The Netherlands, the USA and/or other

countries. All other trademarks are the property of their respective owners.

9.2 Revisions

Revision

Date

Changes

8 Jul 2015

MHA

Initial release

Mouser Electronics

Authorized Distributor

Click to View Pricing, Inventory, Delivery & Lifecycle Information:

Xsens:

MTi-3-8A7G6-DK