Hello World¶

Overview¶

The Hello World sample can be served as a start point of Zephyr application development. This sample is quite simple and just prints Hello World to the serial console.

Requirements¶

Before you start, check that you have the required hardware and software:

• 1x nRF9151 Connect Kit
• 1x USB-C Cable
• A computer running macOS, Ubuntu, or Windows 10 or newer

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 Hello World sample on the command line.

1. Open a terminal window.

2. Go to NCS-Project/nrf9151-connectkit repository cloned in the Getting Started Guide.

3. Build the sample using the west build command, specifying the board (following the -b option) as nrf9151_connectkit/nrf9151.

   west build -p always -b nrf9151_connectkit/nrf9151 samples/hello_world
   

   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.

   Tip

   You can also build this sample for the nrf9151_connectkit/nrf9151/ns target. In such a case, the 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).

   west build -p always -b nrf9151_connectkit/nrf9151/ns samples/hello_world
   

4. After building the sample successfully, the firmware with the name merged.hex can be found in the build directory.

Flashing the firmware¶

Connect the nRF9151 Connect Kit to the computer with a USB-C cable:

Then flash the sample using west flash:

west flash

pyocd load --target nrf91 --frequency 4000000 build/merged.hex

Testing¶

After programming the sample, test it by performing the following steps:

1. Open up a serial terminal, specifying the correct serial port that your computer uses to communicate with the nRF9151 SiP:

   WindowsmacOSUbuntu

   1. Start PuTTY.

   2. Configure the correct serial port and click Open:

      

   Open up a terminal and run:

   screen <serial-port-name> 115200
   

   Open up a terminal and run:

   screen <serial-port-name> 115200
   

2. Press the DFU/RST button to reset the nRF9151 SiP.

3. Observe the output of the terminal. You should see the output, similar to what is shown in the following:

   Terminal
   1 2 3 4 5 6 7 8 9	*** Booting nRF Connect SDK v2.9.99-98a5e50b9ac1 *** *** Using Zephyr OS v3.7.99-693769a5c735 *** [0] Hello World! nrf9151_connectkit/nrf9151 [1] Hello World! nrf9151_connectkit/nrf9151 [2] Hello World! nrf9151_connectkit/nrf9151 [3] Hello World! nrf9151_connectkit/nrf9151 [4] Hello World! nrf9151_connectkit/nrf9151 [5] Hello World! nrf9151_connectkit/nrf9151 ...