SILICON LABS UG310 LTE-M Expansion Kit User Guide
- June 4, 2024
- SILICON LABS
Table of Contents
SILICON LABS UG310 LTE-M Expansion Kit
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
- 2×10-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™
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.
Hardware Overview
Hardware Layout
The layout of the LTE-M Expansion Kit is shown in the figure below.
Connectors
This chapter gives an overview of the LTE-M Expansion Kit connectivity and power connections.
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 peripherals
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.
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.
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. |
Digi XBee Module Socket
The LTE-M Expansion Kit features two 1×10-pin 2mm pitch connectors for
inserting a through-hole Digi XBee wireless module. There are also two
unpopulated footprint for 1×10-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.
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)
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.
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.
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.
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
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:
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.
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.
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.
Kit Revision History
The kit revision can be found printed on the kit packaging label, as outlined in the figure below.
SLEXP8021A Revision History
| Kit Revision | Released | Description |
|---|---|---|
| A00 | 2018-10-15 | Initial release. |
Document Revision History
Revision 1.0
October 2018
- Initial document revision.
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Silicon Labs intends to provide customers with the latest, accurate, and in- depth documentation of all peripherals and modules available for system and software implementers using or intending to use the Silicon Labs products. Characterization data, available modules and peripherals, memory sizes, and memory addresses refer to each specific device, and “Typical” parameters provided can and do vary in different applications. Application examples described herein are for illustrative purposes only. Silicon Labs reserves the right to make changes without further notice and limitation to product information, specifications, and descriptions herein, and does not give warranties as to the accuracy or completeness of the included information. Silicon Labs shall have no liability for the consequences of use of the information supplied herein. This document does not imply or express copyright licenses granted hereunder to design or fabricate any integrated circuits. The products are not designed or authorized to be used within any Life Support System without the specific written consent of Silicon Labs. A “Life Support System” is any product or system intended to support or sustain life and/or health, which, if it fails, can be reasonably expected to result in significant personal injury or death. Silicon Labs products are not designed or authorized for military applications. Silicon Labs products shall under no circumstances be used in weapons of mass destruction including (but not limited to) nuclear, biological or chemical weapons, or missiles capable of delivering such weapons.
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References
- Silicon Labs
- Simplicity Studio - Silicon Labs
- Digi XBee Ecosystem | Everything You Need to Explore and Create Wireless Connectivity | Digi International
- 32-bit MCU - Silicon Labs