LR 2 Click Board™

How Does The LR 2 Click Board™ Work?

The LR 2 Click Board™ as its foundation uses the RN2903, a low-power long-range RF technology-based transceiver module from Microchip Technology. It features the Class A LoRaWAN compliant stack, optimized for robust LoRaWAN networking, immune to interferences, and suitable for long-range wireless operation. It offers a long-range spread spectrum communication with high interference immunity. A receiver with a sensitivity of -148dBm combined with the 18.5dBm integrated amplifier allows for extended range links that can achieve up to 15km in an open area (by the module manufacturer specification). The LR 2 Click Board™ offers data rates of 300kbps with FSK modulation and 12500bps with LoRa Technology modulation and is associated with the 915MHz ISM band suitable for applications in the United States, Canada, Australia, and New Zealand.

To join a LoRaWAN network, the RN2903 requires a LoRaWAN concentrator/gateway. The endpoint device has to use a unique endpoint address, an application session key, and a network session key. The first method is called over-the-air activation (OTAA), where these keys are issued after a specific join procedure. The second method is to assign these keys manually, using UART commands. This method is called activation by personalization (ABP) and can be prone to some security issues. In any case, before an end-device can communicate on the LoRaWAN network, it must be activated.

The LR 2 Click Board™ communicates with MCU using the UART interface with commonly used UART RX and TX pins, including the hardware flow control pins CTS and RTS (Clear to Send, Ready to Send) at data rates up to 57600bps for the data transfer. There are three groups of commands used to configure and operate the separate layers of the RN2903 (SYSTEM, MAC, and RADIO). Each of these layers is controlling a specific area of the module, and every UART command starts with one of the three keywords, which represent an abbreviation of the layer name they are controlling. The module is also equipped with a non-volatile memory (EEPROM) for storing the configuration settings and some additional data.

Explanation of all the configuration parameters, as well as the in-depth explanation of each feature of the RN2903 module, can be found in the Command Reference User's Guide. Please note that improper settings of some parameters might render the device unresponsive. Also, this Click board™ can be reset through the Hardware Reset pin, labelled as RST on the mikroBUS™ socket, by setting this pin to a low logic state.

The LR 2 Click Board™ features the SMA antenna connector with an impedance of 50Ω, so it can be equipped with the appropriate 915MHz compliant antenna that MikroE has in its offer.

The LR 2 Click Board™ can operate with both 3.3V and 5V logic voltage levels selected via the VCC SEL jumper. A proper logic voltage level conversion is performed by the TXB0106 voltage level shifter, while the LDO ensures that recommended values power the module. This allows for both 3.3V and 5V capable MCUs to use the UART communication lines properly. However, the Click board™ comes equipped with a library containing easy-to-use functions and an example code that can be used, as a reference, for further development.

SPECIFICATIONS

PINOUT DIAGRAM

This table shows how the pinout of LR 2 Click Board™ corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns).

Notes	Pin					Pin	Notes
NC	1	AN	PWM	16	NC
Reset	RST	2	RST	INT	15	CTS	UART Clear-To-Send
UART Ready-To-Send	RTS	3	CS	RX	14	TX	UART TX
NC	4	SCK	TX	13	RX	UART RX
NC	5	MISO	SCL	12	NC
NC	6	MOSI	SDA	11	NC
Power supply	+3.3V	7	3.3V	5V	10	+5V	Power supply
Ground	GND	8	GND	GND	9	GND	Ground

ONBOARD SETTINGS AND INDICATORS

LR 2 CLICK ELECTRICAL SPECIFICATIONS