Design

• Sensor reference frames
• Origin of measurements
• Physical connections of the Module
  • Footprint for PCB layout
  • Footprint for standalone mounting
  • Ribbon cable
• Physical connections robust trackers
  • Cables
  • Required antenna specifications
• Mechanical stress
  • Torque
  • Vibrations
• Magnetometer
  • Ferromagnetic materials
  • High currents

This section describes the (mechanical) design and hardware integration considerations of the MTi 600-series module. 3D models of the module and robust trackers are available and found on BASE.

Sensor reference frames

The MTi 600-series uses a right-handed coordinate system as the basis of the sensor frame. The default sensor coordinate system is printed on the side of the MTi and is indicated in the figures below. More details regarding (the modification of) the reference frames of the MTi can be found in the MTi 600-series Datasheet and Family Reference Manual.

Default sensor coordinate system for the MTi 600-series module

Default sensor coordinate system for the MTi-630R

Default sensor coordinate system for the MTi-670G/680G. 
NOTE: In the past (before May 2025) some MTi-670G/-680G units were shipped with labels indicating an incorrect coordinate system. The coordinate system described above is the correct reference.

Origin of measurements

The accelerometer determines the origin of measurements. The in the figures below shows the location of the accelerometer of the MTi 600-series module and robust trackers.

Location origin of measurements for the module (dimensions in mm)

Location origin of measurements for the MTi-630R (dimensions in mm)

Location origin of measurements for the MTi-670/680G (dimensions in mm)

Physical connections of the Module

The connector on the MTi 600-series module is a 16 pins, 1.27 mm pitch male connector of Phoenix Contact (FP 1,27/ 16-MV 1,75 – 1714936). This connector supports an SMD counterpart that can be soldered onto a PCB as well as a ribbon cable (IDC) counterpart. In order to mount the MTi 600-series onto a PCB, the connector should be facing down and the housing should be supported with M2 spacers that can be soldered onto the PCB. When using a ribbon cable, the MTi 600-series can be mounted upside-down to create easy access to the connector.

The figure below shows both mounting options. In both cases, the module is fixated with three M2 screws with a length of at least 12 mm. It is recommended to use screws and spacers with weak magnetic properties to reduce the influence on the internal magnetometer. A tightening torque of 0.1 Nm is recommended to avoid mechanical stress on the module.

Connection options (left: PCB, right: standalone, dimensions in mm)

Footprint for PCB layout

The figure below shows the recommended footprint of the MTi 600-series counterpart connector together with the three spacers.

The table below shows the recommended parts for this mounting option.

Layout footprint example (dimensions in mm)

Footprint for standalone mounting

The figure below shows the mounting hole positions for the MTi 600-series when mounted upside-down for the IDC connection. The table below shows the recommended parts for this mounting option.

Standalone mounting hole positions (dimensions in mm)

At www.phoenixcontact.com, pre-assembled cables can ordered.

Ribbon cable

Ribbon cables with a standard length of 20 centimeters are included in the MTi-630, MTi-670 and MTi-680 Development Kits. Ribbon cables can also be ordered directly from Movella.

Special care has to be taken when removing one of the connectors of these cables and stripping the individual wires; the order of the individual wires can vary across different brands. The table and images below list the wire signals and corresponding numbering for two different brands: Phoenix Contact and HSF. Phoenix connectors can be identified by the Phoenix Contact logo on one side of the connector; HSF connectors do not carry a logo.

Bottom view of the connector and wire pin numbering for Phoenix connectors (left) and HSF connectors (right)

Physical connections robust trackers

The MTi-630R/670G/680G only supports wire connectors. The MTi-670G/680G have three different connectors: a 12-pin ODU connector for main supply and communication, a 4-pin ODU connector for RTCM corrections (unused/unconnected for MTI-670G) and a SMA connector for the GNSS antenna. The MTi-630R only features the 12-pin ODU connector for main supply and communication.

All robust trackers have three (M3) mounting holes to mount them on a flat service. The figures below show the connector and mounting hole positions on the MTi-630R and MTi-670G/680G.

MTi-630R connector and mounting hole positions (dimensions in mm)

MTi-670G/680G connector and mounting hole positions (dimensions in mm)

The figures below show examples of the MTi-630R and MTi-670G/680G mounted on a surface.

MTi-630R mounting example (dimensions in mm)

MTi-670G/680G mounting example (dimensions in mm)

Cables

The following cables can be ordered from Xsens.

CA-MP-USB
The CA-MP-USB cable is a RS232 to USB cable that has the USB converter integrated at the end of the cable and consists of the following parts:

• ODU connector: A10WAM-P12XMM0-0000; AMC HD, break-away plug, 12 circuits.
• Cable: 2.9m length, 12 core, AWG28, shielded, UL, 40ºC ± 85ºC, 5.1mm diameter.
• USB converter

The table below shows the pinning of the connections.

The figures below show the cable length definition (from connector end-to-end).

Host Interface cable CA-MP-USB length definition

CA-MP-12-OPEN

The CA-MP-12-OPEN is a 12-pin Host Interface pigtail cable that consists of the following parts:

• ODU connector: A10WAM-P12XMM0-0000; AMC HD, break-away plug, 12 circuits
• Cable: 2.9 m, 12 core, AWG28, shielded, UL, 40ºC - +85ºC, 6.1 mm diameter

The table below shows the pinning of the connections. The shield of the cable is only connected on the ODU connector side.

The figures below show the cable length definition (from connector end-to-end) and the pinning of the ODU connector.

Host Interface cable length definition

Numbering 12-pin ODU connector (solder cup view).

CA-MP-MTI-12 (deprecated)

The CA-MP-MTI-12 is a 12-pin Host Interface cable that consists of the following parts:

• Molex connector: 5054321201; 1.25mm pitch, dual row, positive lock, 12 circuits
• ODU connector: A10WAMP12XMM0-0000; AMC HD, break-away plug, 12 circuits
• Cable: 2.9 m,  12 core, AWG28, shielded, UL, 40ºC - +85ºC, 6.1 mm diameter
• Molex crimp terminals: 5054311100; gold (Au) plating, 2630 AWG

The table below shows the pinning of the connections. The shield of the cable is only connected on the ODU connector side.

The figures below show the cable length definition (from connector end-to-end) and the pinning of both the Molex connector and the ODU connector. The table below shows the recommended mating parts for the Molex connector.

Host Interface cable length definition

Numbering 12-pin connectors; left Molex (cable entry view), right ODU (solder cup view).

CA-MP-MTI-4

The CA-MP-MTI-4 is the RTCM corrections cable that consists of the following parts:

• Molex connector: 2045320401; 1.25mm pitch, single row, positive lock, 4 circuits
• ODU connector: A1CWAM-P04XBC0-0000; AMC HD, break-away plug, 4 circuits
• Cable: 2.9 m,  12 core, AWG28, shielded, UL, -40ºC - +85ºC
• Molex crimp terminals: 5054311100; gold (Au) plating, 26-30 AWG

The table below shows the pinning of the connections. The shield of the cable is only connected on the ODU connector side.

The figures below show the cable length definition (from connector end-to-end) and the pinning of both the Molex connector and the ODU connector. The table below shows the recommended mating parts for the Molex connector.

RTCM cable length definition

Numbering 4-pin connectors; left Molex (cable entry view), right ODU (solder cup view).

Required antenna specifications

The MTi-670G/680G requires an active antenna with at least the following specifications.

Xsens GNSS/INS Development/Starter Kits include a GNSS patch antenna. In contrast to other antenna types such as helix antennas, patch antennas require a ground plane underneath them to operate properly. A ground plane will reduce errors due to multipathing effects, by blocking signals that can normally reach the GNSS antenna from low or sub-horizon elevations.

Adding a ground plane is not necessary when mounting the antenna directly onto a flat metal surface, such as the roof of a car. Otherwise, we recommend mounting the antenna on top of a metal plate (thickness irrelevant) with a minimum diameter of 10 cm.

For best practices or tailor-made ground planes, we recommend contacting the original manufacturer of the used GNSS antenna. Antennas that are sold by Xsens, as well as their product code and original manufacturer, are listed in this BASE article. For Tallysman patch antennas, best practices were discussed here.

In addition to creating a proper ground plane, avoid mounting the antenna underneath or in close proximity of other metal structures and electronics in order to ensure the best GNSS signal reception.

[1] Including passive losses (filters, cables, connectors etc.)

[2] Measured with a ground plane with 150 mm diameter

[3] At each GNSS system bandwidth. Inter-signal requirement is 50 ns max.

Mechanical stress

In general, it is recommended to place the MTi 600-series module in an area on the PCB where mechanical stress is minimal. The following paragraphs describe possible causes of mechanical stress and ways to reduce it.

Torque

The connector of the MTi 600-series module is soldered onto the PCB board which also contains the sensing elements. Care should be taken to design the mounting such that there is no stress on the connector when mounted on the PCB or connected with a ribbon cable. Any stress on the connector could potentially result in torque on the PCB which can lead to unwanted biases and signal noise. For screws used to mount the MTi 600-series module, a tightening torque of 0.1 Nm is recommended to avoid mechanical stress on the module.

Vibrations

The MTi 600-series features an industry-leading signal processing pipeline (AttitudeEngine^TM) which rejects vibrations. For best results, however, it is recommended that the MTi 600-series is mechanically isolated from vibrations as much as possible. Especially in applications where vibrations are likely to occur, the anchor points of the PCB that holds the MTi 600-series module should be dampened. The required type of dampening varies from application to application.

Magnetometer

The MTi 600-series uses a 3D magnetometer for measuring the geomagnetic field. This part is sensitive to magnetic disturbances. Magnetic disturbances can be calibrated for or identified and rejected by the MTi. However, it is recommended to avoid their influence during hardware integration.

Ferromagnetic materials

Ferromagnetic materials can be magnetized and magnetic behaviour can change during operation. This behaviour will influence the measurements of the 3D magnetometer of the MTi 600-series.

Therefore, it is recommended to keep these ferromagnetic materials away from the MTi 600-series.

High currents

High current power lines on the PCB will introduce magnetic fields that may influence the measurements of the 3D magnetometer of the MTi 600-series. Place high current power lines away from the MTi 600-series. Example: a power line with a current of 100 mA at a distance of 10 mm from the magnetometer, will introduce an error of 2 µT.

More information on magnetic interference can be found in the Family Reference Manual. Static magnetic disturbances can be calibrated for, see the Magnetic Calibration Manual.