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3. Hello, World! Example Tutorial

This example demonstrates the basic Libtropic API and can be used to verify that the chip works correctly. In this example, you will learn about the following functions:

  • lt_init(): function used to initialize context for communication with the TROPIC01,
  • lt_verify_chip_and_start_secure_session(): helper function to start Secure Session and allow L3 communication,
  • lt_ping(): L3 command to verify communication with the TROPIC01,
  • lt_session_abort(): L3 command to abort Secure Session,
  • lt_deinit(): function used to deinitialize context.

Build and Run

Building and running the example

Go to the example's project directory: 

cd examples/stm32/<your_board>/hello_world/

Create a build/ directory and switch to it: 

mkdir build/
cd build/

Open your STM32's serial port using your preferred serial monitor with configuration 8-N-1 and baudrate set to 115200. By default, the serial port is mapped to /dev/ttyACM0. For example, using GTKTerm: 

gtkterm -p /dev/ttyACM0 -s 115200

Warning

Make sure only one serial monitor has the STM32's serial port open, otherwise your output may appear mangled.

And finally, build and run the example: 

cmake ..
make
make flash

TBA

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After this, you should see an output in your serial monitor.

Configuration

In addition to the Libtropic CMake options used to configure Libtropic, this example provides the following CMake options:

  • STLINK_SERIAL_NUMBER (default: none, OpenOCD looks for any STLink programming interface) specifies the serial number of the STLink device used for flashing. This is needed only when you have multiple STM32s connected via built-in STLink or when OpenOCD autodetection does not work:

    Configuring STLink serial number 
    cmake -DSTLINK_SERIAL_NUMBER=<stlink_serial_number> ..
make
make flash

    TBA

    TBA

  • LT_SH0_KEYS (default: "prod0") selects which pairing keys in slot 0 are used. Switch to engineering-sample pairing keys if your TROPIC01 is provisioned with them:

    Switching to engineering sample pairing keys 
    cmake -DLT_SH0_KEYS="eng_sample" ..
make
make flash

    TBA

    TBA

    Additionally, see Default Pairing Keys for a Secure Channel Handshake for more information.