4G LTE-APJ Click Board™ (Asia Pacific)

Product Code: MIKROE-3351

The LARA-R280 module is fully qualified and certified solution which simplifies the design and cuts time to market. It is perfectly suited for a wide range of medium to high-speed M2M applications, such as the smart energy gateways, remote access video cameras, digital signage, telehealth, telematics, and similar applications which rely on a cellular network connection. Note: 4G LTE Click Board™ versions for other regions and operators are also available. How Does The 4G LTE Click Board™Work? The 4G LTE Click Board™ is equipped with the compact LARA-R2 series modem from u-blox. There are several 4G LTE Click Board™ boards which covers different regions using different modules, as: North America - Verizon featuring LARA-R204, North America – AT&T featuring LARA-R202, Asia Pacific featuring LARA-R280, Europe featuring LARA-R211. The main difference between these modules are the supported frequency bands, compliant with the regulations for each region. A complete list of supported bands for each module, along with other relevant info about the module itself, can be found in the LARA-R2 series modem datasheet.

LARA-R2 series modem is the main component of the Click Board™ board and it consists of a number of internal blocks or sections, such as antenna switching and signal conditioning section, RF transceiver section, memory, power management, and most importantly - the cellular baseband processor. This section contains the logic necessary for managing the other sections and provides the interface to the host MCU. This interface consists of several lines used to report the antenna status, sim card status, UART interface lines, reset line, USB interface lines... These lines are routed to the respective elements of the Click Board™ board. The LARA-R2 series module has to be powered with a clean and stable power supply. The voltage needed for the module to work properly is about 4V and it is derived from the 5V mikroBUS™ rail, through the MCP1826, a 1A low drop output (LDO) regulator from Microchip. Although the LARA-R2 series module is a low power device, the cellular network modules, in general, are notorious for their high power consumption, so the 1A LDO had to be used. Digital sections of the LARA-R2 series are internally supplied by 1.8V, so it is necessary to condition the communication bus lines which connect the host MCU with the module. For this reason, another small LDO is used, providing the needed reference voltage for one side of the TXB0106, a 6bit bidirectional level shifting and voltage translator with automatic direction sensing, from Texas Instruments. The reference voltage for the other side of the level shifter is taken from the onboard SMD jumper, labelled as PWR SEL. This jumper is used to select between 3.3V and 5V from the mikroBUS™, depending on the used MCU type and its logic voltage level requirements. The UART bus of the LARA-R2 series module is connected to one side of the level shifter, while the other side (shifted) is connected to the respective mikroBUS™ UART pins. However, the LARA-R2 series module is designed as the traditional DCE device (Data Communication Equipment) offering the full UART pin count, including the hardware flow control pins (CTS, RTS). These pins are routed to the mikroBUS™ CS (RTS) and the INT pin (CTS) and can be used in the MCU software if the hardware flow control is needed. The RI pin is the ringing indicator, and it is routed to the mikroBUS™ PWM pin. Another set of modem control pins is routed to the mikroBUS™ pins, via the level shifter: RI is the ringing indicator pin, and it is routed to the mikroBUS™ PWM pin. This pin indicates the incoming call. The STAT pin is used to signalize the network connection status. This pin is routed both to the mikroBUS™ AN pin through the level shifter, and the yellow LED used to visually indicate the status of the network connection. The transmitting status is indicated by the red TX LED, next to the STAT LED. The PWRKEY pin is routed to the mikroBUS™ RST pin, and it is used during the power-up sequence. A low pulse on this pin will power up the device if the valid supply voltage is provided. To properly detach from the network and store the working parameters in its non-volatile memory, the module should be safely powered off by issuing the AT+CPWROFF command, before disconnecting the power source. One distinctive feature of the E-UTRA physical radio layer used in LTE cellular networks is using the spatial multiplexing antenna technology which allows more than one antenna to be used for better reception of the specific frequency channel. Besides the primary TX/RX antenna, this Click Board™ uses a secondary diversity RX antenna, which allows better signal reception. The 4G LTE Click Board™ is equipped with the micro USB connector. It allows the module to be powered and configured by a personal computer (PC). u-blox company offers a software suite that can be used to configure the LARA-R2 series module.