30 min

Chart your course with utmost precision using ZED-F9P and STM32F446ZE

The art of pinpoint accuracy

GNSS RTK Click with UNI Clicker

Published Sep 02, 2023

Click board™


Development board

UNI Clicker


NECTO Studio



Step into a realm of unparalleled precision with our multi-band GNSS module, seamlessly integrated with cutting-edge multi-band Real Time Kinematics (RTK) technology. Unlock centimeter-level accuracy that revolutionizes the way we navigate and map the world.



Hardware Overview

How does it work?

GNSS RTK Click is based on the ZED-F9P, a multi-band GNSS module with integrated multi-band RTK technology offering centimeter-level accuracy from U-blox. This GNSS receiver can receive and track multiple GNSS constellations. Thanks to the multi-band RF front-end architecture, all four major GNSS constellations (GPS, GLONASS, Galileo, and BeiDou) plus SBAS and QZSS satellites can be received concurrently. Combining GNSS signals from multiple frequency bands (L1/L2/L5) and RTK technology allows the ZED-F9P to achieve centimeter-level accuracy in seconds. Receiving more satellite signals at any given time maximizes the availability of centimeter-level accuracy even in challenging environments such as cities. The ZED-F9P has built-in support for standard RTCM corrections, routed on the additional header, unpopulated by default, and available as an optional standalone RTCM input interface that can not be used as a host interface. It also ensures the security of positioning and navigation information using secure interfaces and advanced jamming and spoofing detection technologies. GNSS RTK Click communicates with MCU using the UART interface at 9600 bps as its default communication protocol with the option for the users to use other interfaces, such as SPI and I2C if they want to configure the module and write the library by themselves. The interface

selection between UART/SPI can be performed by positioning SMD jumpers labeled COMM SEL to an appropriate position. When selecting the SPI communication, with the correct selection of the COMM SEL jumper, it is necessary to set the jumper to DSEL to configure the interface pins as SPI. In the default state, the jumper labeled as DSEL is unpopulated. The receiver also can enter a safe boot mode. If the jumper labeled SFBT is populated and the SAFEBOOT pin is low at Power-Up, the receiver starts in safe boot mode, and GNSS operation is disabled. The USB interface, compatible with the USB version 2.0 FS (Full Speed, 12 Mbit/s), can be used for communication as an alternative to the UART. The USB port can be used as a power supply if you need the Click board™ to be a standalone device. In the case of the main 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. In addition to these features, it also has several GPIO pins. RDY pin routed to the AN pin of the mikroBUS™ socket is used as a communication indicator when bytes are ready to be transmitted, the RST pin routed on the PWM pin of the mikroBUS™ socket provides the ability to reset the receiver, and the TMP pin, with LED

indicator, routed on the INT pin of the mikroBUS™ socket provides clock pulses with configurable duration and frequency. RTK pin routed on the RST pin of the mikroBUS™ socket, alongside the LED indicator labeled RTK, indicates the RTK positioning status. When the LED blinks, it indicates that a valid stream of RTCM messages is being received, but no RTK fixed mode has been achieved. When the LED is constantly lit, the LED indicates that RTK mode has been achieved. It also has another LED indicator labeled as GDC that indicates the current geofence status of whether the receiver is inside any active areas. For example, this feature can be used to wake up a sleeping host when a defined geofence condition is reached. GNSS RTK Click possesses the SMA antenna connector, and it can be used for connecting the appropriate antenna that Mikroe has in its offer, such as GPS Active External Antenna. This antenna is an excellent choice for all GSM/GPRS applications with a frequency range of 1595.42 ± 25MHz. This Click board™ can be operated only with a 5V logic voltage level. The board must perform appropriate logic voltage level conversion before using MCUs with different logic levels. Also, it comes equipped with a library containing functions and an example code that can be used as a reference for further development.

GNSS RTK Click hardware overview image

Features overview

Development board

UNI Clicker is a compact development board designed as a complete solution that brings the flexibility of add-on Click boards™ to your favorite microcontroller, making it a perfect starter kit for implementing your ideas. It supports a wide range of microcontrollers, such as different ARM, PIC32, dsPIC, PIC, and AVR from various vendors like Microchip, ST, NXP, and TI (regardless of their number of pins), four mikroBUS™ sockets for Click board™ connectivity, a USB connector, LED indicators, buttons, a debugger/programmer connector, and two 26-pin headers for interfacing with external electronics. Thanks to innovative manufacturing technology, it allows you to build

gadgets with unique functionalities and features quickly. Each part of the UNI Clicker development kit contains the components necessary for the most efficient operation of the same board. In addition to the possibility of choosing the UNI Clicker programming method, using a third-party programmer or CODEGRIP/mikroProg connected to onboard JTAG/SWD header, the UNI Clicker board also includes a clean and regulated power supply module for the development kit. It provides two ways of board-powering; through the USB Type-C (USB-C) connector, where onboard voltage regulators provide the appropriate voltage levels to each component on the board, or using a Li-Po/Li

Ion battery via an onboard battery connector. All communication methods that mikroBUS™ itself supports are on this board (plus USB HOST/DEVICE), including the well-established mikroBUS™ socket, a standardized socket for the MCU card (SiBRAIN standard), and several user-configurable buttons and LED indicators. UNI Clicker is an integral part of the Mikroe ecosystem, allowing you to create a new application in minutes. Natively supported by Mikroe software tools, it covers many aspects of prototyping thanks to a considerable number of different Click boards™ (over a thousand boards), the number of which is growing every day.

UNI clicker double image

Microcontroller Overview

MCU Card / MCU



8th Generation


ARM Cortex-M4

MCU Memory (KB)


Silicon Vendor


Pin count


RAM (Bytes)


You complete me!


GNSS Active External Antenna is a unique multi-band type of antenna coming from u-Blox that is the perfect selection for high precision GNSS applications, which require highly accurate location abilities such as RTK. The ANN-MB-00 is a multi-band (L1, L2/E5b/B2I) active GNSS antenna with a 5m cable and SMA connector. The antenna supports GPS, GLONASS, Galileo, and BeiDou and includes a high-performance multi-band RHCP dual-feed patch antenna element, a built-in high-gain LNA with SAW pre-filtering, and a 5 m antenna cable with SMA connector, and is waterproof.

GNSS RTK Click accessories image

Used MCU Pins

mikroBUS™ mapper

Transmission Ready Indicator
RTK Positioning Status
SPI Chip Select
SPI Clock
Configurable Time Pulses
I2C Clock
I2C Data
Power Supply

Take a closer look


GNSS RTK Click Schematic schematic

Step by step

Project assembly

UNI Clicker front image hardware assembly

Start by selecting your development board and Click board™. Begin with the UNI Clicker as your development board.

UNI Clicker front image hardware assembly
GNSS2 Click front image hardware assembly
SiBRAIN for STM32F745VG front image hardware assembly
Prog-cut hardware assembly
GNSS2 Click complete accessories setup image hardware assembly
UNI Clicker 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 image step 5 hardware assembly
Necto image step 6 hardware assembly
Necto image step 7 hardware assembly
Necto No Display image step 8 hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Debug Image Necto Step hardware assembly

Track your results in real time

Application Output

After loading the code example, pressing the "DEBUG" button builds and programs it on the selected setup.

Application Output Step 1

After programming is completed, a header with buttons for various actions available in the IDE appears. By clicking the green "PLAY "button, we start reading the results achieved with Click board™.

Application Output Step 3

Upon completion of programming, the Application Output tab is automatically opened, where the achieved result can be read. In case of an inability to perform the Debug function, check if a proper connection between the MCU used by the setup and the CODEGRIP programmer has been established. A detailed explanation of the CODEGRIP-board connection can be found in the CODEGRIP User Manual. Please find it in the RESOURCES section.

Application Output Step 4

Software Support

Library Description

This library contains API for GNSS RTK Click driver.

Key functions:

  • gnssrtk_reset_device - This function resets the device by toggling the RST pin

  • gnssrtk_generic_read - This function reads a desired number of data bytes from the module.

  • gnssrtk_parse_gngga - This function parses the GNGGA 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 Click Example.
 * # Description
 * This example reads and processes data from GNSS RTK click.
 * The demo application is composed of two sections :
 * ## Application Init
 * Initializes driver and starts the module.
 * ## Application Task
 * Reads the received data and parses it.
 * ## Additional Functions
 * - static err_t gnssrtk_process ( void ) - The general process of collecting responses
 *   sent from the module.
 * - static void parser_application ( char *rsp ) - Parsing the response into a more
 *   readable form and printing it on the UART terminal.
 * @author Stefan Nikolic

#include "board.h"
#include "log.h"
#include "gnssrtk.h"
#include "string.h"

#define PROCESS_COUNTER                         10
#define PROCESS_RX_BUFFER_SIZE                  500
#define PROCESS_PARSER_BUFFER_SIZE              500

#define ELEMENT_BUFFER_NULL                     0

static gnssrtk_t gnssrtk;
static log_t logger;

static char current_parser_buf[ PROCESS_PARSER_BUFFER_SIZE ];

// ------------------------------------------------------- ADDITIONAL FUNCTIONS

static void gnssrtk_process ( void )
    int32_t rsp_size;
    uint16_t rsp_cnt = 0;
    char uart_rx_buffer[ PROCESS_RX_BUFFER_SIZE ] = { 0 };
    uint16_t check_buf_cnt;
    uint8_t process_cnt = PROCESS_COUNTER;
    // Clear parser buffer
    memset( current_parser_buf, 0 , PROCESS_PARSER_BUFFER_SIZE ); 
    while( process_cnt != 0 )
        rsp_size = gnssrtk_generic_read( &gnssrtk, &uart_rx_buffer, PROCESS_RX_BUFFER_SIZE );

        if ( rsp_size != -1 )
            // Validation of the received data
            for ( check_buf_cnt = 0; check_buf_cnt < rsp_size; check_buf_cnt++ )
                if ( uart_rx_buffer[ check_buf_cnt ] == 0 ) 
                    uart_rx_buffer[ check_buf_cnt ] = 13;
            // Storages data in parser buffer
            rsp_cnt += rsp_size;
            if ( rsp_cnt < PROCESS_PARSER_BUFFER_SIZE )
                strncat( current_parser_buf, uart_rx_buffer, rsp_size );
            // Clear RX buffer
            memset( uart_rx_buffer, 0, PROCESS_RX_BUFFER_SIZE );
            // Process delay 
            Delay_ms( 100 );

static void parser_application ( char *rsp )
    char element_buf[ 200 ] = { 0 };
    log_printf( &logger, "\r\n-----------------------\r\n", element_buf ); 
    gnssrtk_generic_parser( rsp, GNSSRTK_NMEA_GNGGA, GNSSRTK_GNGGA_LATITUDE, element_buf );
    if ( element_buf[ 0 ] == ELEMENT_BUFFER_NULL )
        log_printf( &logger, "Latitude: No data available!", element_buf );
    else log_printf( &logger, "Latitude:  %s ", element_buf ); 
    memset( element_buf, 0, sizeof( element_buf ) );
    gnssrtk_generic_parser( rsp, GNSSRTK_NMEA_GNGGA, GNSSRTK_GNGGA_LATITUDE_SIDE, element_buf );
    log_printf( &logger, "%s \r\n", element_buf );
    gnssrtk_generic_parser( rsp, GNSSRTK_NMEA_GNGGA, GNSSRTK_GNGGA_LONGITUDE, element_buf );
    if ( element_buf[ 0 ] == ELEMENT_BUFFER_NULL )
        log_printf( &logger, "Longitude: No data available!", element_buf );
    else log_printf( &logger, "Longitude:  %s ", element_buf );
    memset( element_buf, 0, sizeof( element_buf ) );
    gnssrtk_generic_parser( rsp, GNSSRTK_NMEA_GNGGA, GNSSRTK_GNGGA_LONGITUDE_SIDE, element_buf );
    log_printf( &logger, "%s \r\n", element_buf );
    gnssrtk_generic_parser( rsp, GNSSRTK_NMEA_GNGGA, GNSSRTK_GNGGA_ALTITUDE, element_buf );
    if ( element_buf[ 0 ] == ELEMENT_BUFFER_NULL )
        log_printf( &logger, "Alitude: No data available!", element_buf );
    else log_printf( &logger, "Alitude: %s ", element_buf ); 
    memset( element_buf, 0, sizeof( element_buf ) );
    gnssrtk_generic_parser( rsp, GNSSRTK_NMEA_GNGGA, GNSSRTK_GNGGA_ALTITUDE_UNIT, element_buf );
    log_printf( &logger, "%s \r\n", element_buf );

// ------------------------------------------------------ APPLICATION FUNCTIONS

void application_init ( void ) {
    log_cfg_t log_cfg;  /**< Logger config object. */
    gnssrtk_cfg_t gnssrtk_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.

    gnssrtk_cfg_setup( &gnssrtk_cfg );
    GNSSRTK_MAP_MIKROBUS( gnssrtk_cfg, MIKROBUS_1 );
    Delay_ms( 100 );
    err_t init_flag  = gnssrtk_init( &gnssrtk, &gnssrtk_cfg );
    if ( init_flag == UART_ERROR ) {
        log_error( &logger, " Application Init Error. " );
        log_info( &logger, " Please, run program again... " );

        for ( ; ; );

    gnssrtk_default_cfg ( &gnssrtk );
    log_info( &logger, " Application Task " );
    Delay_ms( 100 );

void application_task ( void ) {
    parser_application( current_parser_buf );

void main ( void ) {
    application_init( );

    for ( ; ; ) {
        application_task( );

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

Additional Support