nRF5 SDK CMake

Entropic Engineering's CMake build scripts for the Nordic nRF5 SDK.

Some helper functionality we've found helpful:

• These scripts will automatically locate arm-none-eabi-gcc if it is on your path.

• By default, CMAKE_BUILD_TYPE is set to Debug (in biolerplate.cmake). Additionally, when the build type is Debug, a DEBUG macro is defined (as 1).

• The pca10056_sdk_functions.cmake file adds compile flags for the associated board. It also adds convenience make targets make sdk_config, which launches the CMSIS Config Wizard, and make flash, which will flash the Nordic dev board, or anything attached to it.

Installation Instructions

As a fork

Fork this repository and create an external directory in the project root.

As a submodule

Create an external directory in the project repository and add this repo as a submodule into that external directory.

nRF5 SDK

Download manually from https://www.nordicsemi.com/Software-and-tools/Software/nRF5-SDK

Unpack and place in the external directory. CMake looks for a directory that begins with external/nRF5_SDK*. Alternatively, pass -DSDK_ROOT=<SDK directory> when calling cmake.

GNU Arm embedded toolchain

Install via homebrew on macOS

https://github.com/ARMmbed/homebrew-formulae

$ brew tap ArmMbed/homebrew-formulae
$ brew install arm-none-eabi-gcc

Install via Linux package manager

Most Linux distros will provide a package for gcc-arm-none-eabi which can be installed via the default system package manager, e.g. sudo apt install gcc-arm-none-eabi.

Download From ARM

Download from https://developer.arm.com/tools-and-software/open-source-software/developer-tools/gnu-toolchain/gnu-rm/downloads

Unpack and install where desired (e.g. /usr/local on OS X). Then, either symlink (don't copy) everything from the bin directory of the install to your path (e.g. ln -s /usr/local/gcc-arm-none-eabi-8-2019-q3-update/bin/arm-none-eabi-* /usr/local/bin/), or set the GNUARMEMB_TOOLCHAIN_PATH environment variable.

Build missing SDK dependency

There is one external dependency for the nRF5 SDK that needs to be manually built once. To do so, modify the following commands appropriately for your system:

$ cd external/nRF5_SDK_16.0.0_98a08e2/external/micro-ecc
$ git clone https://github.com/kmackay/micro-ecc.git
$ GNU_INSTALL_ROOT=/usr/local/gcc-arm-none-eabi-8-2019-q3-update/bin/ make -C nrf52hf_armgcc/armgcc/
$ cd -

CMake

Install CMake 3.15+ on your local system. CLion comes bundled with its own version.

Note : The cmake included in your *nix distro may be too old - see below.

To install system-wide, Kitware (makers of CMake) provides additional helpful resources: https://apt.kitware.com/ & https://pypi.org/project/cmake/

Building

cd into project directory (e.g. cd spi_uart), make a build directory (i.e. mkdir build), then cd build, cmake, and make

To make a release build (which you should DEFINITELY do if you have V2 board as the debug uart and channel 1 share pins (badly))

cmake . -B build -DCMAKE_BUILD_TYPE=Release

Flashing

Flashing uses nrfjprog, which is available as part of the nRF Command Line Tools. For convenience, the *_sdk_functions cmake modules provide a make target for flashing, via make flash.

Alternatively, the manual flashing command is: nrfjprog -f nrf52 --program "${name}.hex" --sectorerase --verify --fast --reset

If flashing fails on a new chip, it may be write protected. It can be unlocked with nrfjprog -f nrf52 --recover.

Starting a new project

CMakeLists.txt

Set version requirements, then add required boilerplate, then define project:

cmake_minimum_required(VERSION 3.15)

# Tell CMake where to look for includes
# Select one of:
#set(CMAKE_MODULE_PATH ${CMAKE_SOURCE_DIR}/external/nRF5_CMake/cmake)
# OR
#set(CMAKE_MODULE_PATH ${CMAKE_SOURCE_DIR}/cmake)
include(boilerplate NO_POLICY_SCOPE)

project(spi_uart VERSION 0.0.1
        DESCRIPTION "simple spi to uart bridge"
        LANGUAGES C CXX ASM)

Finally, define executable, add sources, etc. (left as an exercise for the reader)

include(pca10056_sdk_functions) to get helper functions for SDK includes and board flags. See cmake/pca10056_sdk_functions.cmake for details.

config directory

app_config.h

By convention, this is used to define the pins used, default values, app-wide constants, etc. It should be #include'd in main.c.

sdk_config.h

This file enables/disables the various library features. Copy the default from <SDK Root>/config/<chip>/config/sdk_config.h. It can be edited using CMSIS Configuration Wizard from Arm, included under <SDk Root>/external_tools. For convenience, the *_sdk_functions cmake module provides a make target for editing, via make sdk_config.

gcc_nrf52.ld

This is the linker file that indicates what memory regions are used for what purpose. Copy the default from <SDK Root>/config/<chip>/armgcc/generic_gcc_nrf52.ld.