AVR CMake Template Project

This template project serves as a starting point for using an AVR toolchain with CMake.

Setup

1. In order to use the template, some variables have to be defined in the CMakeList.txt:

set(TARGET <your target/project name>)

set(MCU <mmcu variable, e.g. atmega4809>)
set(F_CPU <CPU frequency>)

set(AVRDUDE_MCU <corresponding MCU identifier for avrdude, e.g. m4809>)
set(AVRDUDE_PROGRAMMER_ID <your programmer identifier, e.g. pkobn_updi>)

# Optionally, use pymcuprog instead of avrdude:
#
# set(TOOLCHAIN_USE_PYMCUPROG true)

# Optional: specify the desired language standard
set(CMAKE_C_STANDARD 11)
set(CMAKE_CXX_STANDARD 14)

2. Thereafter, the toolchain can be included with: include(cmake/Toolchain.cmake).

3. The project needs to be defined with the function configure_target(${TARGET} <your sources>).

Please refer to the example project for the full outline of the CMakeLists.txt. Note that for newer devices, a device pack might be needed. The boolean TOOLCHAIN_NEED_DEVICE_PACK specifies this. If this variable is set to true, Toolchain.cmake will look for a device_pack folder at the root of the project and set up the necessary compiler flags for using the device pack with the given MCU specified. The device packs can be found at Microchip Packs Repository. Download the pack for your device and unzip it into a folder named device_pack in the root of your project: unzip <device_pack>.atpack -d device_pack.

Use

Once the CMakeLists.txt has been defined, the project can be compiled and uploaded by issuing:

• mkdir build && cd build
• cmake ..
• make -j
• make upload

Defined targets

Toolchain.cmake defines the following convenience targets in addition to default make targets:

• make upload: Upload using avrdude.
• make upload_eeprom: Upload eeprom using avrdude.
• make disassemble: Disassemble the .elf file.

LSP

The Toolchain.cmake file is set to generate a compile_commands.json compilation database for use with e.g. clangd. It is advised to keep a symlink pointing from the root of the project to the build folder: ln -s build/compile_commands.json compile_commands.json.

In order for clangd to work properly with avr-gcc, a .clangd file is provided in the example project. Moreover, clangd has to be started with --query-driver=<path to avr-gcc/avr-g++>. For Neovim users, the following Lua snippet is useful for setting this up with lspconfig:

local build_clangd_command = function()
	local path = ""
	local handle = io.popen("which avr-gcc")

	if handle ~= nil then
		local output = handle:read("*a")
		path = output:gsub("[\n\r]", "")
		-- We want to allow for g++ as well, so replace with a wildcard
		path = path:gsub("gcc$", "g*")
		handle:close()
	end

	return {
		"clangd",
		string.format("--query-driver=%s", path),
	}
end

lspconfig["clangd"].setup({
	cmd = build_clangd_command(),
}