nRF5 CMake

This repository provides platform-agnostic CMake files that can be used to build custom nRF5 projects. Our goal is to cover the most used libraries and examples starting from nRF5 SDK version 15.3.0.

How to use

Copy all CMake files from the ./cmake folder located in this repository to your project location and create a basic CMakeLists.txt file:

cmake_minimum_required(VERSION 3.14)
project(blinky LANGUAGES C ASM)

include("nrf5")
add_executable(${CMAKE_PROJECT_NAME}
  "${NRF5_SDK_PATH}/examples/peripheral/blinky/main.c"
)

nrf5_target(${CMAKE_PROJECT_NAME})
target_link_libraries(${CMAKE_PROJECT_NAME} PRIVATE
  nrf5_nrfx_common
  nrf5_delay
  nrf5_boards
)

The above example compiles source from the SDK but the user is expected to copy main.c and modify it instead. Below you can look at a very basic bash script, which builds and flashes blinky example.

#!/bin/bash

# Generate project inside ./build folder.
cmake \
    -S . \
    -B build \
    -DCMAKE_TOOLCHAIN_FILE="./cmake/arm-none-eabi.cmake" \
    -DTOOLCHAIN_PREFIX="/Users/przemyslawlenart/git/nrf5-cmake/ci/toolchains/gcc" \
    -DNRF5_SDK_PATH="/Users/przemyslawlenart/git/nrf5-cmake/ci/sdks/16.0.0" \
    -DNRF5_BOARD="pca10056" \
    -DNRF5_SOFTDEVICE_VARIANT="s140"

# Build project
cmake --build build

# Erase all
cmake --build build --target erase_all

# Flash SoftDevice (if used)
cmake --build build --target flash_softdevice

# Flash progarm
cmake --build build --target flash

You can find more examples in the repo's ./ci/examples/ folder. Make sure to check all available cached variables, which are documented below and read Contributing readme file if you plan to automate SDK and tool downloads.

Configuration

CMake files are configured with cached variables. A lot of them are optional and can be deduced from other ones or SDK itself. Specify -DNAME=VALUE during project generation to pass them.

CMAKE_TOOLCHAIN_FILE (file path, requred)

Specifies a file path to the toolchain file which points to the ARM compiler utilities. Currently, only GCC toolchain is supported and arm-none-eabi.cmake file is included in ./cmake folder, which you should copy to your project.

TOOLCHAIN_PREFIX (directory path, optional)

Path to the directory containing GCC toolchain. If not specified, version installed globally is used.

NRF5_SDK_PATH (directory path, required)

Specifies a path to the nRF5 SDK, which should be used during compilation. Root directory should include folders like examples, components etc.

NRF5_SDK_VERSION (version string, optional)

You can explicily specify SDK version (e.g. "16.0.0"). When this cached variable is not provided, version is deduced from the SDK file contents.

NRF5_BOARD (board name, optional)

If you are using the nRF board you can specify it (e.g. "pca10056") and the value of NRF5_TARGET will be deduced accordingly. If defined, all board-specific defines (like -DBOARD_PCA10056) are included for all source files during compilation.

NRF5_TARGET (target name, optional)

If NRF5_BOARD is not specified, this variable is required. You can use alias value like nrf52840, but full target name is recommended: nrf52840_xxaa. CMake file will deduce all chip specific flags during compilation for all project sources (e.g. "-mcpu=cortex-m4").

NRF5_SOFTDEVICE_VARIANT (soft device name, required)

This variable specifies the SoftDevice binary. If the project doesn't require SoftDevice you can pass "blank" value, otherwise set SoftDevice name (e.g. "s140"). Following triple: (NRF5_SDK_VERSION, NRF5_TARGET, NRF5_SOFTDEVICE_VARIANT) is then verified to check if the combination is well supported. All SoftDevice related defines are included for all source files (e.g. "-DNRF_SD_BLE_API_VERSION=7"). The flash_softdevice target should be pointing to the correct SoftDevice file.

NRF5_SDKCONFIG_PATH (directory path, optional)

It is highly recommended to specify a path to custom "sdk_config.h" file. Otherwise, based on the above variables' values, the CMake file tries to find the best matching file from the SDK. If you want to create a custom target which depends on the config file, link nrf5_config dependency. All builtin libraries are doing it by default.

NRF5_APPCONFIG_PATH (directory path, optional)

If your project is using app_config.h you can provide include directory pointing to this file.

NRF5_LINKER_SCRIPT (file path, optional)

It is highly recommended to specify a path to custom linker file. Otherwise, based on the above variables' values, the CMake file tries to find the best matching file from the SDK.

NRF5_NRFJPROG (executable file, optional)

Path to the nrfjprog executable used by targets flashing programs. If not specified, globally installed binary is used.

NRF5_STACK_SIZE (size in bytes, optional)

Defines __STACK_SIZE compile definition accordingly. If not passed, the startup file (.S) will take care of setting up default stack boundaries for the specified target.

NRF5_HEAP_SIZE (size in bytes, optional)

Defines __HEAP_SIZE compile definition accordingly. If not passed, the startup file (.S) will take care of setting up default heap boundaries for the specified target.

NRF_JLINK_SN (SEGGER J-Link serial number, optional)

Tells nrfjprog utility which SEGGER J-Link debugger to use based on its serial number. Particularily useful when working with multiple J-Links connected to the PC at the same time. If not specified, user may be prompted which J-Link to use when running commands like flashing and erasing.

Important: You must clear CMake cache and re-run CMake in order to change it.

Contributing

The project is developed in a semi-automated way and thoroughly tested with CI by compiling both SDK provided examples and libraries. You can find more information about the project's setup, structure, scripts, etc. in ./ci/README.md file.

Thank you!

License

MIT License

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