UG310: LTE-M Expansion Kit User's Guide The LTE-M Expansion Kit is an excellent way to explore and evaluate the Digi XBee3TM 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-efm32xbee. LTE-M EXP BOARD FEATURES * EXP connector for interfacing Silicon Labs MCU and Wireless Starter Kits * 2x10-pin socket supporting Digi XBeeTM and Digi XBee ProTM 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 StudioTM 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 . . . . . . . 3.1.1 Pass-through EXP Header 3.1.2 EXP Header Pinout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 . 6 . 6 3.2 Digi XBee Module Socket . . . . 3.2.1 Digi XBee Module Socket Pinout 3.2.2 Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 . 8 . 9 4. Using the LTE-M Expansion Kit 4.1 Board Identification . . . . . . . . . . . . . . . . . . . . . . . . . 10 . . . . . . . . . . . . . . . . . . . . . . . . . .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 silabs.com | Building a more connected world. Rev. 1.0 | 2 UG310: LTE-M Expansion Kit User's Guide Introduction 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 LTEM EXP Board is designed to be compatible with all Digi XBee through-hole modules offering a wide array of wireless connectivity options, 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 Simplicity StudioTM. For more information about the Digi XBee modules see https://www.digi.com/xbee. silabs.com | Building a more connected world. Rev. 1.0 | 3 UG310: LTE-M Expansion Kit User's Guide Hardware Overview 2. Hardware Overview 2.1 Hardware Layout The layout of the LTE-M Expansion Kit is shown in the figure below. GNSS Receiver Digi XBee Module Breakout Header Not mounted ASSOC Status LED Digi XBee Module Socket EXP-header for Starter Kits Digi XBee Module Reset Digi XBee Module Breakout Header Not mounted Pass-through EXP-header Not mounted Power source select switch Figure 2.1. LTE-M Expansion Kit Hardware Layout silabs.com | Building a more connected world. Rev. 1.0 | 4 UG310: LTE-M Expansion Kit User's Guide Connectors 3. Connectors This chapter gives an overview of the LTE-M Expansion Kit connectivity and power connections. Digi XBee Socket Breakout (Not Mounted) EXP Header Digi XBee Socket Digi XBee Socket Breakout (Not Mounted) Pass-through EXP Header (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 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. 3V3 5V XBEE_PWM1 GNSS_TXD GNSS_RXD XBEE_RTS XBEE_DIO4 XBEE_DOUT XBEE_DIN VMCU 20 18 16 14 12 10 8 6 4 2 19 17 15 13 11 9 7 5 3 1 BOARD_ID_SDA BOARD_ID_SCL XBEE_ADC1 XBEE_RSSI XBEE_CTS GNSS_VBCKP_EN GNSS_POWER_EN XBEE_DTR GNSS_TIMEPULSE GND LTE-M EXP Board I/O Pin Reserved (Board Identification) Figure 3.2. EXP Header silabs.com | Building a more connected world. Rev. 1.0 | 5 UG310: LTE-M Expansion Kit User's Guide Connectors 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 daisychaining 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 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. silabs.com | Building a more connected world. Digi XBee module UART DTR Rev. 1.0 | 6 UG310: LTE-M Expansion Kit User's Guide Connectors 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. G N XBD E XB E_ D XBEE TR _B XBEE KG _P XBEE W O _R M E XB E SS 1 _R I XBEE ES _D E E XB E IO Tn _D 1 XBEE IN 2 EE_DO _V U C T C 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. 10 9 8 7 6 5 4 3 2 1 11 12 13 14 15 16 17 18 19 20 0 C D 1 _A C EE_AD 2 XBEE DC3 _A XB E DC E _A XBEE TS C _R O XB E SS E _A F XBEE RE _V XB E N E _O XBEE TS C 4 _ XBEE IO _D XBEE XB Figure 3.3. Digi XBee Module Socket silabs.com | Building a more connected world. Rev. 1.0 | 7 UG310: LTE-M Expansion Kit User's Guide Connectors 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) silabs.com | Building a more connected world. Rev. 1.0 | 8 UG310: LTE-M Expansion Kit User's Guide Connectors 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 LTEM 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 VMCU 3.3V 5V Low Power (AEM) Power Switch XBEE_VCC Digi XBee Socket 5V IN 3.3 V OUT High Power (DC-DC) DC-DC GNSS Receiver Figure 3.4. LTE-M Expansion Kit Power Topology silabs.com | Building a more connected world. Rev. 1.0 | 9 UG310: LTE-M Expansion Kit User's Guide Using the LTE-M Expansion Kit 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 silabs.com | Building a more connected world. Rev. 1.0 | 10 UG310: LTE-M Expansion Kit User's Guide Using the LTE-M Expansion Kit 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 window, 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: XBEE_VCC VDD EXP Header EXP_HEADER7 EXP_HEADER9 EXP_HEADER12 EXP_HEADER14 EXP_HEADER3 GNSS_PWR_ENABLE GNSS_VBCKP GNSS_RXD GNSS Receiver GNSS_TXD GNSS_TIMEPULSE Figure 4.2. On-Board GNSS Receiver Connection Diagram Table 4.1. GNSS Receiver Signal Descriptions Signal GNSS Power Enable GNSS Backup Power (VBCKP) Description Connects the GNSS receiver's main power input to the same power rail as the XBee module socket 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 silabs.com | Building a more connected world. Provides an output pulse at a configurable interval (default: 1 second), synchronized to the received GNSS signal. Rev. 1.0 | 11 UG310: LTE-M Expansion Kit User's Guide Using the LTE-M Expansion Kit 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 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 significantly reduced if the VBCKP power has not been removed since the last valid 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 powered. silabs.com | Building a more connected world. Mode description Rev. 1.0 | 12 UG310: LTE-M Expansion Kit User's Guide Schematics, Assembly Drawings, and BOM 5. Schematics, Assembly Drawings, and BOM Schematics, assembly drawings, and bill of materials (BOM) are available through Simplicity Studio when the kit documentation package has been installed. They are also available from the Silicon Labs website and kit page. silabs.com | Building a more connected world. Rev. 1.0 | 13 UG310: LTE-M Expansion Kit User's Guide Kit Revision History 6. Kit Revision History The kit revision can be found printed on the kit packaging label, as outlined in the figure below. LTE-M Expansion Kit SLEXP8021A 18-10-15 124802042 A00 Figure 6.1. Kit Label 6.1 SLEXP8021A Revision History Kit Revision Released Description A00 2018-10-15 Initial release. silabs.com | Building a more connected world. Rev. 1.0 | 14 UG310: LTE-M Expansion Kit User's Guide Document Revision History 7. Document Revision History Revision 1.0 October, 2018 * Initial document revision. silabs.com | Building a more connected world. Rev. 1.0 | 15 Simplicity Studio One-click access to MCU and wireless tools, documentation, software, source code libraries & more. Available for Windows, Mac and Linux! IoT Portfolio www.silabs.com/IoT SW/HW www.silabs.com/simplicity Quality www.silabs.com/quality Support and Community community.silabs.com Disclaimer 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. 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