20 min

Elevate your positioning accuracy to unparalleled heights with LC29H(DA/EA) and TM4C129LNCZAD

Ensure your position is always on point, no matter the terrain or challenge

GNSS RTK 3 Click with UNI-DS v8

Published Nov 15, 2023

Click board™

GNSS RTK 3 Click

Development board



NECTO Studio



Experience the future of positioning with our GNSS RTK solution, where real-time kinematic capabilities meet cutting-edge innovation to deliver pinpoint accuracy.



Hardware Overview

How does it work?

GNSS RTK 3 Click is based on the LC29H(DA/EA), 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 LC29H(DA/EA) module features an integrated AGNSS, integrated AIC, and jamming function and can receive 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 Click has an SMA antenna connector for connecting an appropriate antenna, also offered by MIKROE. 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 saves all relevant data 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. In both cases, the module will use the NMEA 0183/RTCM 3.x protocols. You can update the LC29H(DA/EA) 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 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.

GNSS RTK 3 Click hardware overview image

Features overview

Development board

UNI-DS v8 is a development board specially designed for the needs of rapid development of embedded applications. It supports a wide range of microcontrollers, such as different STM32, Kinetis, TIVA, CEC, MSP, PIC, dsPIC, PIC32, and AVR MCUs regardless of their number of pins, and a broad set of unique functions, such as the first-ever embedded debugger/programmer over WiFi. The development board is well organized and designed so that the end-user has all the necessary elements, such as switches, buttons, indicators, connectors, and others, in one place. Thanks to innovative manufacturing technology, UNI-DS v8 provides a fluid and immersive working experience, allowing access anywhere and under any

circumstances at any time. Each part of the UNI-DS v8 development board contains the components necessary for the most efficient operation of the same board. An advanced integrated CODEGRIP programmer/debugger module offers many valuable programming/debugging options, including support for JTAG, SWD, and SWO Trace (Single Wire Output)), and seamless integration with the Mikroe software environment. Besides, it also includes a clean and regulated power supply module for the development board. It can use a wide range of external power sources, including a battery, an external 12V power supply, and a power source via the USB Type-C (USB-C) connector. Communication options such as USB-UART, USB

HOST/DEVICE, CAN (on the MCU card, if supported), and Ethernet is also included. In addition, it also has the well-established mikroBUS™ standard, a standardized socket for the MCU card (SiBRAIN standard), and two display options for the TFT board line of products and character-based LCD. UNI-DS v8 is an integral part of the Mikroe ecosystem for rapid development. Natively supported by Mikroe software tools, it covers many aspects of prototyping and development thanks to a considerable number of different Click boards™ (over a thousand boards), the number of which is growing every day.

UNI-DS v8 horizontal image

Microcontroller Overview

MCU Card / MCU



8th Generation


ARM Cortex-M4

MCU Memory (KB)


Silicon Vendor

Texas Instruments

Pin count


RAM (Bytes)


You complete me!


GNSS L1/L5 Active External Antenna (YB0017AA) is an active patch antenna from Quectel that supports GNSS L1/L5 BD B1/B2 GLONASS L1, offering excellent performance with its high gain and efficiency for fleet management, navigation, RTK, and many other tracking applications. The magnetic-mounting antenna, with dimensions of 61.5×56.5×23mm, is designed to work with various ground plane sizes or in free space and is connected to the device by a 3m cable with an SMA male connector.

 GNSS RTK 3 Click accessories image

Used MCU Pins

mikroBUS™ mapper

Reset / ID SEL
SPI Select / ID COMM
Power Supply
External sync
Timepulse Output
I2C Clock
I2C Data
Power Supply

Take a closer look


GNSS RTK 3 Click Schematic schematic

Step by step

Project assembly

Fusion for PIC v8 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the UNI-DS v8 as your development board.

Fusion for PIC v8 front image hardware assembly
GNSS2 Click front image hardware assembly
SiBRAIN for PIC32MZ1024EFK144 front image hardware assembly
GNSS2 Click complete accessories setup image hardware assembly
v8 SiBRAIN Access MB 1 - upright/background hardware assembly
Necto image step 2 hardware assembly
Necto image step 3 hardware assembly
Necto image step 4 hardware assembly
NECTO Compiler Selection Step Image hardware assembly
NECTO Output Selection Step Image hardware assembly
Necto image step 6 hardware assembly
Necto image step 7 hardware assembly
Necto image step 8 hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Necto PreFlash Image hardware assembly

Track your results in real time

Application Output

After pressing the "FLASH" button on the left-side panel, it is necessary to open the UART terminal to display the achieved results. By clicking on the Tools icon in the right-hand panel, multiple different functions are displayed, among which is the UART Terminal. Click on the offered "UART Terminal" icon.

UART Application Output Step 1

Once the UART terminal is opened, the window takes on a new form. At the top of the tab are two buttons, one for adjusting the parameters of the UART terminal and the other for connecting the UART terminal. The tab's lower part is reserved for displaying the achieved results. Before connecting, the terminal has a Disconnected status, indicating that the terminal is not yet active. Before connecting, it is necessary to check the set parameters of the UART terminal. Click on the "OPTIONS" button.

UART Application Output Step 2

In the newly opened UART Terminal Options field, we check if the terminal settings are correct, such as the set port and the Baud rate of UART communication. If the data is not displayed properly, it is possible that the Baud rate value is not set correctly and needs to be adjusted to 115200. If all the parameters are set correctly, click on "CONFIGURE".

UART Application Output Step 3

The next step is to click on the "CONNECT" button, after which the terminal status changes from Disconnected to Connected in green, and the data is displayed in the Received data field.

UART Application Output Step 4

Software Support

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.

Open Source

Code example

This example can be found in NECTO Studio. Feel free to download the code, or you can copy the code below.

 * @file main.c
 * @brief GNSS RTK 3 Click Example.
 * # Description
 * This example demonstrates the use of GNSS RTK 3 click by reading and displaying
 * the GNSS coordinates.
 * The demo application is composed of two sections :
 * ## Application Init
 * Initializes the driver and enables the click board.
 * ## Application Task
 * Reads the received data, parses the NMEA GGA info from it, and once it receives 
 * the position fix it will start displaying the coordinates on the USB UART.
 * ## Additional Function
 * - static void gnssrtk3_clear_app_buf ( void )
 * - static void gnssrtk3_log_app_buf ( void )
 * - static err_t gnssrtk3_process ( gnssrtk3_t *ctx )
 * - static void gnssrtk3_parser_application ( uint8_t *rsp )
 * @author Stefan Filipovic

#include "board.h"
#include "log.h"
#include "gnssrtk3.h"

// Application buffer size
#define APP_BUFFER_SIZE             800
#define PROCESS_BUFFER_SIZE         200

static gnssrtk3_t gnssrtk3;
static log_t logger;

static uint8_t app_buf[ APP_BUFFER_SIZE ] = { 0 };
static int32_t app_buf_len = 0;
static uint8_t i2c_data_ready = 0;

 * @brief GNSS RTK 3 clearing application buffer.
 * @details This function clears memory of application buffer and reset its length.
 * @note None.
static void gnssrtk3_clear_app_buf ( void );

 * @brief GNSS RTK 3 log application buffer.
 * @details This function logs data from application buffer to USB UART.
 * @note None.
static void gnssrtk3_log_app_buf ( void );

 * @brief GNSS RTK 3 data reading function.
 * @details This function reads data from device and concatenates data to application buffer. 
 * @param[in] ctx : Click context object.
 * See #gnssrtk3_t object definition for detailed explanation.
 * @return @li @c  0 - Read some data.
 *         @li @c -1 - Nothing is read.
 * See #err_t definition for detailed explanation.
 * @note None.
static err_t gnssrtk3_process ( gnssrtk3_t *ctx );

 * @brief GNSS RTK 3 parser application.
 * @param[in] rsp Response buffer.
 * @details This function logs GNSS data on the USB UART.
 * @return None.
 * @note None.
static void gnssrtk3_parser_application ( uint8_t *rsp );

void application_init ( void ) 
    log_cfg_t log_cfg;  /**< Logger config object. */
    gnssrtk3_cfg_t gnssrtk3_cfg;  /**< Click config object. */

     * Logger initialization.
     * Default baud rate: 115200
     * Default log level: LOG_LEVEL_DEBUG
     * @note If USB_UART_RX and USB_UART_TX 
     * are defined as HAL_PIN_NC, you will 
     * need to define them manually for log to work. 
     * See @b LOG_MAP_USB_UART macro definition for detailed explanation.
    LOG_MAP_USB_UART( log_cfg );
    log_init( &logger, &log_cfg );
    log_info( &logger, " Application Init " );

    // Click initialization.
    gnssrtk3_cfg_setup( &gnssrtk3_cfg );
    GNSSRTK3_MAP_MIKROBUS( gnssrtk3_cfg, MIKROBUS_1 );
    if ( GNSSRTK3_OK != gnssrtk3_init( &gnssrtk3, &gnssrtk3_cfg ) ) 
        log_error( &logger, " Communication init." );
        for ( ; ; );
    gnssrtk3_enable_device ( &gnssrtk3 );
    log_info( &logger, " Application Task " );

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

void main ( void ) 
    application_init( );

    for ( ; ; ) 
        application_task( );

static void gnssrtk3_clear_app_buf ( void ) 
    memset( app_buf, 0, app_buf_len );
    app_buf_len = 0;

static void gnssrtk3_log_app_buf ( void )
    for ( int32_t buf_cnt = 0; buf_cnt < app_buf_len; buf_cnt++ )
        log_printf( &logger, "%c", app_buf[ buf_cnt ] );

static err_t gnssrtk3_process ( gnssrtk3_t *ctx ) 
    uint8_t rx_buf[ PROCESS_BUFFER_SIZE ] = { 0 };
    int32_t overflow_bytes = 0;
    int32_t rx_cnt = 0;
    int32_t rx_size = 0;
    if ( ( GNSSRTK3_DRV_SEL_I2C == ctx->drv_sel ) && ( !i2c_data_ready ) )
        uint16_t pps_wait_log_cnt = 0;
        while ( !gnssrtk3_get_pps_pin ( ctx ) )
            if ( ++pps_wait_log_cnt > 5000 )
                log_printf( &logger, " Waiting for the position fix (PPS signal)...\r\n\n" );
                pps_wait_log_cnt = 0;
            Delay_ms ( 1 );
        i2c_data_ready = 1;
        Delay_ms ( 200 );
    rx_size = gnssrtk3_generic_read( ctx, rx_buf, PROCESS_BUFFER_SIZE );
    if ( ( rx_size > 0 ) && ( rx_size <= APP_BUFFER_SIZE ) ) 
        if ( ( app_buf_len + rx_size ) > APP_BUFFER_SIZE ) 
            overflow_bytes = ( app_buf_len + rx_size ) - APP_BUFFER_SIZE;
            app_buf_len = APP_BUFFER_SIZE - rx_size;
            memmove ( app_buf, &app_buf[ overflow_bytes ], app_buf_len );
            memset ( &app_buf[ app_buf_len ], 0, overflow_bytes );
        for ( rx_cnt = 0; rx_cnt < rx_size; rx_cnt++ ) 
            if ( rx_buf[ rx_cnt ] ) 
                app_buf[ app_buf_len++ ] = rx_buf[ rx_cnt ];
        return GNSSRTK3_OK;
    return GNSSRTK3_ERROR;

static void gnssrtk3_parser_application ( uint8_t *rsp )
    uint8_t element_buf[ 100 ] = { 0 };
    if ( GNSSRTK3_OK == gnssrtk3_parse_gga( rsp, GNSSRTK3_GGA_LATITUDE, element_buf ) )
        static uint8_t wait_for_fix_cnt = 0;
        if ( strlen( element_buf ) > 0 )
            log_printf( &logger, "\r\n Latitude: %.2s degrees, %s minutes \r\n", element_buf, &element_buf[ 2 ] );
            memset( element_buf, 0, sizeof( element_buf ) );
            gnssrtk3_parse_gga( rsp, GNSSRTK3_GGA_LONGITUDE, element_buf );
            log_printf( &logger, " Longitude: %.3s degrees, %s minutes \r\n", element_buf, &element_buf[ 3 ] );
            memset( element_buf, 0, sizeof( element_buf ) );
            gnssrtk3_parse_gga( rsp, GNSSRTK3_GGA_ALTITUDE, element_buf );
            log_printf( &logger, " Altitude: %s m \r\n", element_buf );
            wait_for_fix_cnt = 0;
            if ( wait_for_fix_cnt % 5 == 0 )
                log_printf( &logger, " Waiting for the position fix...\r\n\n" );
                wait_for_fix_cnt = 0;
        gnssrtk3_clear_app_buf(  );
        i2c_data_ready = 0;

// ------------------------------------------------------------------------ END

Additional Support