GNSS 21 Click

How does it work?

GNSS 21 Click is based on the PNT-SG3FS, a Global Navigation Satellite System (GNSS) module from Lantronix, built around the Teseo III GNSS receiver by STMicroelectronics. Designed to provide reliable and precise positioning, this module supports multi-constellation satellite tracking with the ability to simultaneously monitor up to 32 satellite signals. It covers a wide range of navigation systems, including GPS L1C/A, Galileo E1B/C, BeiDou B1, GLONASS L1OF, QZSS L1C/A, and SBAS L1C/A services such as WAAS, EGNOS, MSAS, and GAGAN. For improved positioning accuracy, the module offers Differential GPS (DGPS) capabilities in compliance with RTCM 10402.3 and supports advanced Assisted GNSS techniques using either local ephemeris prediction or server-based assistance, enabling fast acquisition and minimal Time to First Fix (TTFF), even under challenging conditions.

In addition to its core navigation capabilities, the PNT-SG3FS integrates a 16Mb flash memory, allowing for a rich feature set including data logging, geofencing, odometer functionality, firmware updates, and up to 5 days of autonomous assisted GNSS data retention. The onboard temperature-compensated crystal oscillator (TCXO) ensures high stability and accuracy in navigation performance, while the integrated real-time clock (RTC) oscillator supports clock trimming to optimize timing precision based on the 32.768kHz crystal, making it suitable for time-sensitive applications.

The PNT-SG3FS is capable of delivering highly accurate positioning with a circular error probable (CEP) of 1.5 meters, and when used alongside external RTK or PPP client algorithms, it can achieve sub-decimeter accuracy, under 10 centimeters. It boasts a remarkable -163dBm tracking sensitivity and can achieve a cold start TTFF in less than 32 seconds. Certified for compliance with various international standards including the Radio Equipment Directive (RED) 2014/53/EU and several ETSI and EN norms, GNSS 21 Click ensures reliable performance and regulatory approval across a wide range of applications.

This Click board™ is designed in a unique format supporting the newly introduced MIKROE feature called “Click Snap.” Unlike the standardized version of Click boards, this feature allows the main module area to become movable by breaking the PCB, opening up many new possibilities for implementation. Thanks to the Snap feature, the PNT-SG3FS can operate autonomously by accessing its signals directly on the pins marked 1-8. Additionally, the Snap part includes a specified and fixed screw hole position, enabling users to secure the Snap board in their desired location.

The GNSS 21 Click communicates with the host MCU through a UART interface using the standard UART RX and TX pins. The default communication speed is set at 115200bps, ensuring efficient data exchange. It also provides an I2C interface for communication with a host MCU in the I2C Fast speed mode (400kHz). Still, it must be noted that the I2C interface can only be operated in the peripheral mode.

Along with the communication and control pins, this Click board™ also includes a reset pin (RST) and a RESET button, enabling easy module resetting, the timepulse signal indicator (PPS), offering precise time synchronization for applications that require it, module wake-up signal in a form of a test point labeled WUP, and a battery holder for the backup power supply (RAM and RTC backup). The board also features one u.Fl connector for GNSS antenna that MIKROE offers, like the Active GPS antenna combined with an IPEX-SMA cable for flexible and efficient connectivity options.

This Click board™ can be operated only with a 3.3V logic voltage level. The board must perform appropriate logic voltage level conversion before using MCUs with different logic levels. It also comes equipped with a library containing functions and example code that can be used as a reference for further development.

Click Snap

Click Snap is an innovative feature of our standardized Click add-on boards, designed to bring greater flexibility and optimize your prototypes. By simply snapping the PCB along predefined lines, you can easily detach the main sensor/IC/module area, reducing the overall size, weight, and power consumption – ideal for the final phase of prototyping. For more details about Click Snap, visit the official page dedicated to this feature.

Specifications

Pinout diagram

This table shows how the pinout on GNSS 21 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	NC
Reset	RST	2	RST	INT	15	PPS	Time Pulse Output
ID COMM	CS	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	NC
Ground	GND	8	GND	GND	9	GND	Ground

Onboard settings and indicators

GNSS 21 Click electrical specifications

Software Support

GNSS 21 Click demo application is developed using the NECTO Studio, ensuring compatibility with mikroSDK‘s open-source libraries and tools. Designed for plug-and-play implementation and testing, the demo is fully compatible with all development, starter, and mikromedia boards featuring a mikroBUS™ socket.

Example Description

This example demonstrates the use of GNSS 21 Click by reading and displaying the GNSS coordinates.

Key Functions

• gnss21_cfg_setup Config Object Initialization function.
• gnss21_init Initialization function.
• gnss21_generic_read This function reads a desired number of data bytes by using UART or I2C serial interface.
• gnss21_parse_gga This function parses the GGA data from the read response buffer.
• gnss21_reset_device This function resets the device by toggling the RST pin.

Application Init

Initializes the driver and logger.

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.

Application Output

This Click board can be interfaced and monitored in two ways:

• Application Output – Use the “Application Output” window in Debug mode for real-time data monitoring. Set it up properly by following this tutorial.
• UART Terminal – Monitor data via the UART Terminal using a USB to UART converter. For detailed instructions, check out this tutorial.

Additional Notes and Information

The complete application code and a ready-to-use project are available through the NECTO Studio Package Manager for direct installation in the NECTO Studio. The application code can also be found on the MIKROE GitHub account.