SLEXP8021A - SILICON LABS - Datasheet.Support

UG310: LTE-M Expansion Kit User's Guide

The LTE-M Expansion Kit is an excellent way to explore and

evaluate the Digi XBee3™ LTE-M cellular module which allows

you to add low-power long range wireless connectivity to your

EFM32/EFR32 embedded application.

The Digi XBee3 LTE-M cellular module is an easy-to-use cellular module. The LTE-M

Expansion Kit easily integrates and brings LTE-M connectivity to compatible Silicon

Labs Wireless and MCU Starter Kits through the expansion header.

To get started with the LTE-M Expansion Kit go to http://www.silabs.com/start-efm32-

xbee.

LTE-M EXP BOARD FEATURES

• EXP connector for interfacing Silicon

Labs MCU and Wireless Starter Kits

• 2x10-pin socket supporting Digi XBee™

and Digi XBee Pro™ through-hole

modules

• Digi XBee module can be powered by

(W)STK supply rail or on-board DC-DC

regulator

• U-blox CAM-M8Q GNSS receiver

supporting GPS and GLONASS

SOFTWARE SUPPORT

• Software examples for the EFM32GG11

Starter Kit are available in Simplicity

Studio™

silabs.com | Building a more connected world. Rev. 1.0

Table of Contents

1. Introduction ................................3

2. Hardware Overview .............................4

2.1 Hardware Layout .............................4

3. Connectors ................................5

3.1 EXP Header ...............................5

3.1.1 Pass-through EXP Header ........................6

3.1.2 EXP Header Pinout ...........................6

3.2 Digi XBee Module Socket ..........................7

3.2.1 Digi XBee Module Socket Pinout ......................8

3.2.2 Power Supply .............................9

4. Using the LTE-M Expansion Kit .......................10

4.1 Board Identification ............................10

4.2 Digi XBee3 LTE-M Module ..........................10

4.3 On-Board GNSS Receiver ..........................11

5. Schematics, Assembly Drawings, and BOM ...................13

6. Kit Revision History ............................14

6.1 SLEXP8021A Revision History ........................14

7. Document Revision History .........................15

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1. Introduction

This user guide covers the usage of the Silicon Labs LTE-M EXP Board together with the Digi XBee3 LTE-M cellular module. The LTE-

M EXP Board is designed to be compatible with all Digi XBee through-hole modules offering a wide array of wireless connectivity op-

tions, such as Zigbee, Wi-Fi, 3G and LTE cellular to name a few.

Software examples demonstrating how to use the LTE-M Expansion Kit with the EFM32GG11 Starter Kit are available through Simplici-

ty Studio™.

For more information about the Digi XBee modules see https://www.digi.com/xbee.

UG310: LTE-M Expansion Kit User's Guide

Introduction

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2. Hardware Overview

2.1 Hardware Layout

The layout of the LTE-M Expansion Kit is shown in the figure below.

EXP-header for

Starter Kits

Power source

select switch

Pass-through EXP-header

Not mounted

Digi XBee Module Reset

GNSS Receiver

Digi XBee Module Socket

ASSOC Status LED

Digi XBee Module Breakout Header

Not mounted

Digi XBee Module Breakout Header

Not mounted

Figure 2.1. LTE-M Expansion Kit Hardware Layout

UG310: LTE-M Expansion Kit User's Guide

Hardware Overview

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3. Connectors

This chapter gives an overview of the LTE-M Expansion Kit connectivity and power connections.

EXP Header

Pass-through

EXP Header

(Not Mounted)

Digi XBee Socket

Digi XBee Socket Breakout

(Not Mounted)

Digi XBee Socket Breakout

(Not Mounted)

Figure 3.1. LTE-M Expansion Kit Connector Layout

3.1 EXP Header

On the left side of the LTE-M Expansion Kit, a right-angle female 20-pin EXP header is provided to allow connection to one of Silicon

Labs’ MCU or Wireless Starter Kits. The EXP header on the Starter Kits follows a standard which ensures that commonly used periph-

erals such as an SPI, a UART, and an I2C bus, are available on fixed locations on the connector. Additionally, the VMCU, 3V3 and 5V

power rails are also available on the EXP header. For detailed information regarding the pinout to the EXP header on a specific Starter

Kit, consult the accompanying kit user’s guide.

The figure below shows how the Digi XBee module socket and the on-board GNSS receiver are connected to the EXP header and the

peripheral functions that are available.

1516

20 19

VMCU

XBEE_DIN

XBEE_DOUT

XBEE_DIO4

XBEE_RTS

GNSS_RXD

GNSS_TXD

XBEE_PWM1

3V3

GND

GNSS_TIMEPULSE

XBEE_DTR

GNSS_POWER_EN

GNSS_VBCKP_EN

XBEE_CTS

XBEE_RSSI

XBEE_ADC1

BOARD_ID_SDA

BOARD_ID_SCL

Reserved (Board Identification)

LTE-M EXP Board I/O Pin

Figure 3.2. EXP Header

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Connectors

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3.1.1 Pass-through EXP Header

The LTE-M Expansion Kit features a footprint for a secondary EXP header. All signals from the EXP header, including those that are

not connected to any features on the LTE-M Expansion Kit are directly tied to the corresponding pins in the footprint, allowing daisy-

chaining of additional EXP boards if a connector is soldered in.

Pin 1 of the secondary EXP header is marked with a 1 in the silkscreen printing.

3.1.2 EXP Header Pinout

The table below shows the pin assignments of the EXP header.

Table 3.1. EXP Header Pinout

Pin Signal Name Function

2 VMCU 3.3V Input to low power side of power switch

4 XBEE_DIN Digi XBee module UART input

6 XBEE_DOUT Digi XBee module UART output

8 XBEE_DIO4 Digi XBee module digital I/O

10 XBEE_RTS Digi XBee module UART RTS

12 GNSS_RXD GNSS receiver UART input

14 GNSS_TXD GNSS receiver UART output

16 XBEE_PWM1 Digi XBee module PWM output

18 5V Board 5V supply. Used to supply DC-DC regulator.

20 3V3 Board 3V3 supply. Only used for board identification EEPROM.

1 GND System ground

3 GNSS_TIMEPULSE GNSS receiver synchronized timepulse output

5 XBEE_DTR Digi XBee module UART DTR

7 GNSS_POWER_EN GNSS receiver main power enable

9 GNSS_VBCKP_EN GNSS receiver backup power supply

11 XBEE_CTS Digi XBee module UART CTS

13 XBEE_RSSI Digi XBee module RSSI output

15 XBEE_ADC1 Digi XBee module analog input

17 BOARD_ID_SCL Identification of expansion boards.

19 BOARD_ID_SDA Identification of expansion boards.

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Connectors

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3.2 Digi XBee Module Socket

The LTE-M Expansion Kit features two 1x10-pin 2mm pitch connectors for inserting a through-hole Digi XBee wireless module. There

are also two unpopulated footprint for 1x10-pin 2.54mm (0.1") pitch pin headers which breaks out the signals of the Digi XBee module

socket, an ASSOC status LED which indicates the wireless connection status of the Digi XBee module, and a reset button connected to

the Digi XBee module's reset signal input.

The pinout of the socket is illustrated in the figure below. The pinout of the unpopulated breakout headers are identical to the adjacent

Digi XBee module socket connector.

XBEE_DIN

XBEE_CTS

XBEE_DOUT

XBEE_RTS

GND

2 1

XBEE_VCC

XBEE_DIO12

XBEE_ADC1

XBEE_DIO4

XBEE_PWM1

XBEE_DTR

XBEE_RESETn

XBEE_RSSI

XBEE_ADC0

XBEE_ADC2

XBEE_ADC3

XBEE_ASSOC

XBEE_VREF

XBEE_BKGO

XBEE_ON

16 18 19 20

11 13 14 15

Figure 3.3. Digi XBee Module Socket

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Connectors

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3.2.1 Digi XBee Module Socket Pinout

The pin assignment of the Digi XBee module socket is given in the table below.

Table 3.2. Digi XBee Module Socket Pin Descriptions

Pin Number Digi XBee Module Signal

Top row

1 Digi XBee VCC

2 DOUT (Module UART TXD)

3 DIN (Module UART RXD)

4 DIO12 (Digital IO 12)

5 RESETn

6 RSSI (Module RF Received Signal Strength Indicator output)

7 PWM1 (Module PWM output)

8 Not Connected

9 DTR (Module UART DTR)

10 GND

Bottom row

11 DIO4 (Digital IO 4)

12 CTS (Module UART CTS)

13 ON (Module status output)

14 VREF

15 ASSOC (Module wireless connection status output)

16 RTS (Module UART RTS)

17 ADC3 (Analog input 3)

18 ADC2 (Analog input 2)

19 ADC1 (Analog input 1)

20 ADC0 (Analog input 0)

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Connectors

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3.2.2 Power Supply

When connected to a Silicon Labs MCU or Wireless STK, the Digi XBee3 LTE-M cellular module can either be powered by the VMCU

rail present on the EXP header, or through a DC-DC regulator onboard the LTE-M Expansion Kit. If connected to the VMCU rail of the

starter kit, the current consumption of the Digi XBee3 LTE-M cellular module will be included in the starter kit's on-board Advanced

Energy Monitor (AEM). The DC-DC regulator draws power from the 5V net, and hence, the power consumption of the Digi XBee3 LTE-

M cellular module will not be included in any AEM measurements performed by the MCU STK.

A mechanical power switch on the LTE-M Expansion Kit is used to select between Low Power (AEM) mode and High Power (DC-DC)

mode. When the switch is set to Low Power (AEM) mode, the Digi XBee3 LTE-M cellular module is connected to the VMCU net on the

EXP header. For most MCU Starter Kits, the regulator supplying the VMCU net is capable of sourcing up to 300 mA, bearing in mind

that the MCU is also powered from this net. The EFM32GG11 starter kit and the Wireless Starter Kit main board are able to source up

to 800 mA on the VMCU net (provided that the kit's power source is able to supply this much current). When the switch is set to High

Power (DC-DC) mode, the Digi XBee3 LTE-M cellular module is connected to the output of the DC-DC converter, which is able to

source up to 2 A (again, limited by the capability of the source powering the starter kit). For applications requiring higher power than

what is available from the VMCU net, the power switch should be set to High Power (DC-DC) mode.

The on-board GNSS receiver is powered from the same rail as the Digi XBee3 LTE-M cellular module through an analog switch that

can be controlled by a GPIO pin on the EXP header.

The power topology is illustrated in the figure below.

EXP Header

Power

Switch

Low

Power

(AEM)

High

Power

(DC-DC)

XBEE_VCC

DC-DC

IN OUT

3.3 V

Digi XBee

Socket

VMCU 3.3V

GNSS

Receiver

Figure 3.4. LTE-M Expansion Kit Power Topology

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Connectors

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4. Using the LTE-M Expansion Kit

The Digi XBee3 LTE-M cellular module is a wireless module providing cellular connectivity using the low-power LTE-M technology.

4.1 Board Identification

The LTE-M EXP Board and the starter kit it is connected to are automatically identified by Simplicity Studio when connected to the

computer to present the correct documentation and software examples. Note however that Simplicity studio is not able to identify which

Digi XBee module is inserted into the LTE-M EXP Board's Digi XBee module socket.

4.2 Digi XBee3 LTE-M Module

The Digi XBee3 LTE-M module requires an external antenna to enable wireless connectivity. Connect the included patch antenna to the

module's u.FL connector labeled 'CELL' and insert the module into the socket as shown in the figure below, before connecting the

board to a Silicon Labs MCU or Wireless starter kit.

The kit also includes a SIM card, which needs to be activated before being inserted into the SIM slot of the Digi XBee3 LTE-M module.

Refer to the LTE-M Expansion Kit Quick Start Guide for information on how to activate the SIM card.

Figure 4.1. LTE-M Expansion Kit assembled for use

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Using the LTE-M Expansion Kit

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4.3 On-Board GNSS Receiver

The LTE-M Expansion Kit is equipped with a U-Blox Cam-M8Q Global Navigation Satellite System (GNSS) receiver module that allows

the user to retrieve position and time information and use it in their embedded application.

The U-Blox Cam-M8Q can receive signals from both the GPS and GLONASS GNSS constellations, which provides good worldwide

coverage. A reasonably clear view of the sky is required to obtain signal reception, meaning the GNSS receiver will work best outdoors.

Indoor operation with reduced position accuracy is possible if the receiver has a reasonably clear view of the sky through a glass win-

dow, though the reliability will be unpredictable.

The GNSS receiver will output the current time and position (given that a satellite fix has been aquired) as well as satellite fix status

over a UART interface using either the NMEA-0183 (default) or proprietary UBX protocol. Configuration commands can be input to the

receiver using the same protocols. In addition, the receiver supports input of Differential GPS (DGPS) correction data using the RTCM

10402.3 protocol.

For more information about the GNSS receiver refer to the following documents:

•U-Blox Cam-M8Q Datasheet

•U-Blox M8 Receiver Description Including Protocol Specification

The figure below shows how the GNSS receiver is connected to the rest of the board. The table below describes the signals:

GNSS_PWR_ENABLE

EXP_HEADER3

EXP_HEADER7

XBEE_VCC

VDD

EXP Header

GNSS_TIMEPULSE

GNSS

Receiver

GNSS_TXD

GNSS_RXD

GNSS_VBCKP

EXP_HEADER9

EXP_HEADER12

EXP_HEADER14

Figure 4.2. On-Board GNSS Receiver Connection Diagram

Table 4.1. GNSS Receiver Signal Descriptions

Signal Description

GNSS Power Enable Connects the GNSS receiver's main power input to the same power rail as the

XBee module socket

GNSS Backup Power (VBCKP) GNSS receiver RAM and RTC backup power supply. Must be high in order to use

the GNSS receiver.

GNSS TXD GNSS receiver UART output. 9600 bps 8N1 frame format.

GNSS RXD GNSS receiver UART input.

GNSS Timepulse Provides an output pulse at a configurable interval (default: 1 second), synchron-

ized to the received GNSS signal.

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Using the LTE-M Expansion Kit

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The GNSS receiver can be enabled, disabled or kept in sleep mode with RAM powered and RTC running depending on the state of the

GNSS_PWR_ENABLE and GNSS_VBCKP pins according to the table below:

Table 4.2. GNSS Receiver Power Modes

GNSS_PWR_EN GNSS_VBCKP Mode description

LOW LOW GNSS receiver powered off

LOW HIGH Sleep mode - GNSS receiver core, RF frontend and UART interface powered

off. RAM and RTC are powered. Time to re-acquire time and position fix is sig-

nificantly reduced if the VBCKP power has not been removed since the last val-

id time and position fix. Current consumption at the VBCKP pin in this mode is

approx. 15 uA.

HIGH HIGH Active mode - GNSS receiver is active with all features available.

HIGH LOW Invalid mode - VBCKP needs to be high whenever the GNSS receiver is pow-

ered.

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Using the LTE-M Expansion Kit

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5. Schematics, Assembly Drawings, and BOM

Schematics, assembly drawings, and bill of materials (BOM) are available through Simplicity Studio when the kit documentation pack-

age has been installed. They are also available from the Silicon Labs website and kit page.

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Schematics, Assembly Drawings, and BOM

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6. Kit Revision History

The kit revision can be found printed on the kit packaging label, as outlined in the figure below.

SLEXP8021A

LTE-M Expansion Kit

124802042

18-10-15

A00

Figure 6.1. Kit Label

6.1 SLEXP8021A Revision History

Kit Revision Released Description

A00 2018-10-15 Initial release.

UG310: LTE-M Expansion Kit User's Guide

Kit Revision History

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7. Document Revision History

Revision 1.0

October, 2018

• Initial document revision.

UG310: LTE-M Expansion Kit User's Guide

Document Revision History

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