GNSS RTK 3 Click – LC29HDA

NOTE: To ensure the best performance of your GNSS RTK 3 Click, we recommend using the GNSS L1/L5 Active External Antenna available from MIKROE.

How does it work?

GNSS RTK 3 Click is based on the LC29HDA, a dual-band, multi-castellation GNSS module from Quectel. With internal LNA and SAW filters, the module achieves better sensitivity and anti-interference capability. Dual frequency support helps the module deliver CEP accuracy values of 1m in autonomous mode and centimeter levels while using the RTK functionality. Integrated RTK (Real-Time Kinetic) position engine provides a sub-meter accuracy with fast convergence time and outstanding performance. This module supports the RTK Rover technique. Before implementing the RTK navigation technique, the module must receive the RTK differential data via its UART port. After validating the differential correction data, the module will enter differential or RTK float mode. The expected accuracy at RTK fixed mode is lower than 20cm.

The LC29HDA module features an integrated AGNSS function, integrated AIC, and jamming function and is capable of reception of L1 and L5 GNSS band signals concurrently. The receiver chip is built using 12nm technology and provides advanced power management, which enables low-power GNSS sensing and position fix, which in turn makes the module ideal for power-sensitive and battery-powered systems. There is a DSEL switch with 0 and 1 positions. By setting it to a 0 position, the UART interface can be used for communication and downloading, while the I2C can only be used for communication. The 1 position sets UART for downloading only, while the I2C interface can be used for communication and downloading.

The GNSS RTK 3 Module has an SMA antenna connector for connecting an appropriate antenna, also offered by MIKROE, such as a GNSS L1/L5 Active External Antenna. This antenna is an excellent choice for all GNSS applications supporting L1 and L5 band frequencies. You can also control the antenna by deactivating it in power-saving mode, lowering power consumption.

To interface different voltage levels of the host MCU, GNSS RTK 3 Click is equipped with the TXS0108E, an 8-bit bi-directional level-shifting voltage translator from Texas Instruments. In case of a mains supply failure, the module can use a backup supply voltage from a connected battery. Backup voltage supplies the real-time clock and battery-backed RAM and enables all relevant data to be saved in the backup RAM to allow a hot or warm start later. If no battery is present, the backup is powered over the 3.3V rail of the mikroBUS™ socket.

As mentioned, the GNSS RTK 3 Click uses a standard 2-Wire UART interface to communicate with the host MCU with commonly used UART RX and TX pins. The UART 2 interface pins are exposed on a 1.8V DBG header for debugging purposes. The module supports baud rates 9600 up to 3Mbps, while the 115200bps is the default. Besides the UART interface, you can also use a standard 2-Wire I2C interface to communicate with the host MCU with a data rate of up to 400kbps. The module will use the NMEA 0183/RTCM 3.x protocols in both cases. You can update the LC29HDA firmware using any of those interfaces. Using the RST pin, you can reset the module or wake it up using the WUP pin. Besides the 1PPS LED, the one pulse per second can also be monitored over the PPS pin.

This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the VCC SEL jumper. This way, both 3.3V and 5V capable MCUs can use the communication lines properly. Also, this 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 on GNSS RTK 3 Click 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	WUP	Wake-up
Reset / ID SEL	RST	2	RST	INT	15	PPS	Timepulse Output
Device Enable / ID COMM	CE	3	CS	RX	14	TX	UART TX
	NC	4	SCK	TX	13	RX	UART RX
	NC	5	MISO	SCL	12	SCL	I2C Clock
	NC	6	MOSI	SDA	11	SDA	I2C Data
Power Supply	3.3V	7	3.3V	5V	10	5V	Power Supply
Ground	GND	8	GND	GND	9	GND	Ground

Onboard settings and indicators

GNSS RTK 3 Click electrical specifications

Software Support

We provide a library for the GNSS RTK 3 Click as well as a demo application (example), developed using MIKROE compilers. The demo can run on all the main MIKROE development boards.

Package can be downloaded/installed directly from NECTO Studio Package Manager(recommended), downloaded from our LibStock™ or found on Mikroe github account.

Library Description

This library contains API for GNSS RTK 3 Click driver.

Key functions

• gnssrtk3_enable_device This function enables the device by setting the CEN pin to high logic state.

• gnssrtk3_generic_read This function reads a desired number of data bytes by using UART or I2C serial interface.

• gnssrtk3_parse_gga This function parses the GGA data from the read response buffer.

Example Description

This example demonstrates the use of GNSS RTK 3 click by reading and displaying the GNSS coordinates.

void application_task ( void ) 
 { 
     if ( GNSSRTK3_OK == gnssrtk3_process( &gnssrtk3 ) )  
     { 
         gnssrtk3_parser_application( app_buf ); 
     } 
 }

The full application code, and ready to use projects can be installed directly from NECTO Studio Package Manager(recommended), downloaded from our LibStock™ or found on Mikroe github account.

Other Mikroe Libraries used in the example:

• MikroSDK.Board
• MikroSDK.Log
• Click.GNSSRTK3

Additional notes and informations

Depending on the development board you are using, you may need USB UART click, USB UART 2 Click or RS232 Click to connect to your PC, for development systems with no UART to USB interface available on the board. UART terminal is available in all MIKROE compilers.

mikroSDK

This Click board™ is supported with mikroSDK – MIKROE Software Development Kit. To ensure proper operation of mikroSDK compliant Click board™ demo applications, mikroSDK should be downloaded from the LibStock and installed for the compiler you are using.

For more information about mikroSDK, visit the official page.