Shield board

• Connections and peripheral switch
  • GNSS extension socket
• Pin descriptions
• Power supplies
• Electrical specifications
• Absolute maximum ratings
• Package drawing

The MTi 1-s modules are available with a development kit. An MTi-3 AHRS or an MTi-7/8 external-GNSS/INS is mounted in a PLCC-28 socket and connected to USB, UART, I²C and SPI. The Shield Board exposes the pins of the MTi 1-s module, making it easier for the user to test all the features and the peripherals offered by the MTi 1-s. This chapter discusses in more detail the connections and peripherals available on the MTi 1-s Shield Board.

Connections and peripheral switch

The MTi 1-series Shield Board has the following connections as shown in the figure below:  MTi 1-series Shield Board with connector designators:

• External power pin header (J100)
• Arduino-compatible headers (P100, P101, P102 and P103)
• UART communication extension socket, not placed by default (P202 and P203)
• Micro USB (J102)
• Peripheral selection switch (SW200)
• Auxiliary sensor extension socket (P200 and P201) used for GNSS daughter card
• MTi 1-series module placed in J101

MTi 1-series Shield Board with connector designators

The External power pin header J100 can be used to directly supply the VDDIO and/or VDDA supplies for the MTi 1-s module (Table Connections on external power header). The IOREF pin on this connector can be used to override the default 3.3 V VDDIO by placing a jumper from this pin to the adjacent VDDIO pin.

The connections for Arduino-compatible headers with a pitch of 2.54 mm (0.1 inch) are shown in the table below. The MTi 1-series Shield Board does not support Arduino-compatible boards with an IOREF of 5V as the maximum VDDIO is 3.6V for the MTi 1-s module. Therefore, the VDDIO is by default set to 3.3V. This default VDDIO voltage can be overruled by placing a jumper on the external power header, but only for voltages within the operational VDDIO range of the MTi 1-s module. For information on the connections, refer to the pin description in Section Pin Descriptions Refer to the table Connections on Arduino-compatible header on how to enable the various interfaces on the Shield Board.

The UART communication extension socket is not placed by default. When the socket is placed, it can be used to directly plug an UART transceiver module of MikroElektronika like the ‘RS232 click’ or ‘RS485 click 3.3V’. This UART communication extension socket uses (only) the 3.3V supply pin, which is connected to VDDIO. We recommend to place low profile sockets (like the CES-108-01-T-S) to make sure that the MTi 1-s module is still easily accessible. The pin description of these headers is shown in the table Connections on UART communication extension sockets.

The MTi 1-series Shield Board has a Micro USB connection that can be connected directly to a USB port on a PC or laptop. Note: Make sure to disconnect any other power supply, as this will overrule the USB connection.

The Peripheral selection switch sets the interface configuration of the MTi 1-s module in the socket. The switch connects the PSEL lines (Table Switch positions to enable interfaces on Shield Board) to GND with a 5 kΩ pull-down when set to ON. Otherwise, the PSEL lines are pulled-up with a 100 kΩ resistor. The PSEL pins on the Arduino-compatible headers can be used to overrule these lines.

GNSS extension socket

The MTi-7-DK and MTi-8-DK come with a GNSS daughter card installed in the auxiliary sensor extension sockets (P200 and P201). As shown in the figure below, the MTi-7-DK GNSS daughter card consists of a GNSS and a barometer sensor component. The LEDs (Power and PPS) give an indication of the proper functioning of the GNSS daughter card. The supplied GNSS antenna can be connected to the SMA connector.

Top view (left) and the bottom view (right) of the MTi-7-DK GNSS daughter card

The MTi-8-DK comes with an RTK GNSS daughter card. As shown in the figures below, the RTK GNSS daughter card consists of an RTK GNSS receiver, a barometer sensor component, an Xbee socket and a USB connector. The LEDs (Power, PPS, Xbee and RTK status) give an indication of proper functioning of the RTK GNSS daughter card and Xbee power. The supplied GNSS antenna can be connected to the SMA connector.

Top view (left) and the bottom view (right) of the MTi-8-DK RTK GNSS daughter card

The RTK GNSS daughter card is equipped with an XBee module socket. XBee modules are embedded solutions providing wireless end-point connectivity to devices. The XBee socket can be used to feed RTCM correction messages to the MTi-8-DK RTK GNSS receiver or to connect to an XBee wireless module.

XBee socket pinning

The RTK GNSS daughter card (GNSS-RTK-DK-D) also features a Safeboot pin which can be used in case communication issues with the GNSS module on the daughter card arise. Please refer to BASE for instructions on how to use this pin and how to retrieve communication.

The auxiliary sensor extension socket has mikroBUS™ compatible pinning. This enables the user to connect alternate GNSS daughter card modules with mikroBUS™ pinning to the MTi 1-series Shield board. The pinning connections for the auxiliary sensor extension socket are listed in Connections on auxiliary sensor extension sockets.

Pin descriptions

Power supplies

The MTi 1-series module requires two different power supplies: VDDIO (used for the MCU and all IO) and VDDA (used as an analog supply for the sensing elements).

The Shield Board has five supply inputs:

1. USB: supplies both VDDIO and VDDA at 3.3V. Forces USB mode (SPI/I2C/UART interfaces not available).
2. 5V (P101): supplies both VDDIO and VDDA at 3.3V. Forces USB mode (SPI/I2C/UART interfaces not available).
3. 3V3 (P101): supplies VDDIO directly and overrides USB mode (SPI/I2C/UART interfaces available).
4. VDDIO (J100): supplies VDDIO directly, overrides all other VDDIO supplies and overrides USB mode (SPI/I2C/UART interfaces available).
5. VDDA (J100): supplies VDDA directly.

Note: Only supplying VDDIO (through 3V3 (P101) or VDDIO (J100)) without supplying VDDA is not recommended. The only single supply options are USB and 5V (P101), but in both cases the Shield Board will be forced into USB mode.

Electrical specifications

The Shield Board has the same communication protocol as the MTi 1-s module. The table System specification Shield Board shows the electrical specifications for the Shield Board.

Absolute maximum ratings

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only. Functional operation of the device in these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Make sure not to apply force on the components of the MTi 1-s module, especially when placing the MTi 1-s module in a PLCC socket.

Package drawing

MTi 1-series Shield Board package drawing (Top and Side view)

(Note: the hole size is 3.2mm for M3 screw) 

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

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