GNSS¶
Overview¶
The GNSS sample demonstrates how to use the GNSS interface to control the GNSS module.
The sample first initializes the GNSS module. Then it handles events from the interface, reads the associated data and outputs information to the console. Because NMEA data needs to be read as soon as an NMEA event is received, a Zephyr message queue is used for buffering the NMEA strings. The event handler function reads the received NMEA strings and puts those into the message queue. The consumer loop reads from the queue and outputs the strings to the console.
Requirements¶
Before you start, check that you have the required hardware and software:
- 1x nRF9151 Connect Kit
- 1x nano-SIM card with LTE-M or NB-IoT support
- 1x U.FL cabled LTE-M/NB-IoT/NR+ Flexible Antenna (included in the box)
- 1x U.FL cabled GNSS Antenna (included in the box)
- 1x USB-C Cable
- A computer running macOS, Ubuntu, or Windows 10 or newer
Set up your board¶
- Insert the nano-SIM card into the nano-SIM card slot.
- Attach the U.FL cabled LTE-M/NB-IoT/NR+ Flexible Antenna.
- Attach the U.FL cabled GNSS Antenna.
- Connect the nRF9151 Connect Kit to the computer with a USB-C cable.
Building the sample¶
To build the sample, follow the instructions in Getting Started Guide to set up your preferred building environment.
Use the following steps to build the GNSS sample on the command line.
-
Open a terminal window.
-
Go to
NCS-Project/nrf9151-connectkit
repository cloned in the Getting Started Guide. -
Build the sample using the
west build
command, specifying the board (following the-b
option) asnrf9151_connectkit/nrf9151/ns
.The
-p
always option forces a pristine build, and is recommended for new users. Users may also use the-p auto
option, which will use heuristics to determine if a pristine build is required, such as when building another sample.Note
This sample has Cortex-M Security Extensions (CMSE) enabled and separates the firmware between Non-Secure Processing Environment (NSPE) and Secure Processing Environment (SPE). Because of this, it automatically includes the Trusted Firmware-M (TF-M).
-
After building the sample successfully, the firmware with the name
merged.hex
can be found in thebuild
directory.
Flashing the firmware¶
Set up your board before flashing the firmware. You can flash the sample using west flash
:
Tip
In case you wonder, the west flash
will execute the following command:
Testing¶
After programming the sample, test it by performing the following steps:
-
Open up a serial terminal, specifying the correct serial port that your computer uses to communicate with the nRF9151 SiP:
- Start PuTTY.
-
Configure the correct serial port and click Open:
-
Press the DFU/RST button to reset the nRF9151 SiP.
-
Observe that the following information is displayed in the terminal:
-
Observe that the following information is displayed upon acquiring a fix:
Optimize GNSS reception
- GNSS signals do not usually penetrate ceilings or other structures that well. For best GNSS performance, the antenna should be placed outside on a flat surface in an open space far from sources of interference and other structures that can block the satellite signals.
- The GNSS patch antenna achieves the highest gain when placed horizontally on a surface (x-y) facing the z-axis since it can receive all propagated GNSS signals. A lower gain is experienced if the patch antenna is mounted at an angle.