Arm Toolchain for Embedded

Arm Toolchain for Embedded (ATfE) is a free, open-source LLVM-based toolchain for bare-metal Arm development. It targets Cortex-M, Cortex-R, and Cortex-A processors from Armv6-M and newer, and includes clang, lld, libc++, compiler-rt, and picolibc.

ATfE is the successor to the LLVM Embedded Toolchain for Arm. The LLVM Embedded Toolchain for Arm repository is deprecated; use ATfE for LLVM 20 and later.

Pre-built binaries are available for Windows (x86_64), macOS (universal), and Linux (x86_64 and AArch64) hosts.

Install Arm Toolchain for Embedded on Windows

To download the latest release from GitHub, copy and paste the following URL into your browser:

    

        
        
https://github.com/arm/arm-toolchain/releases/download/release-22.1.0-ATfE/ATfE-22.1.0-Windows-x86_64.zip

    

Extract the zip file to a location of your choice on your host machine.

Open Windows Control Panel and add the ATfE bin directory to the Path.

Open a Command Prompt and test your installation .

Install Arm Toolchain for Embedded on macOS

To download the latest release from GitHub, copy and paste the following URL into your browser:

    

        
        
https://github.com/arm/arm-toolchain/releases/download/release-22.1.0-ATfE/ATfE-22.1.0-Darwin-universal.dmg

    

Install the toolchain by opening the .dmg file and following the instructions.

Add the ATfE bin directory to your PATH:

    

        
        
export PATH=/Applications/ATfE-22.1.0-Darwin-universal/bin:$PATH

    

The toolchain binaries might be quarantined. Navigate to the bin directory and use the xattr command to remove the quarantine:

    

        
        
cd /Applications/ATfE-22.1.0-Darwin-universal/bin
find . -type f -perm +0111 | xargs xattr -d com.apple.quarantine

    

You can now test your installation .

Install Arm Toolchain for Embedded on Linux

The following steps assume Ubuntu Linux on an AArch64 host. Modify the filenames and paths as needed for other hosts or x86_64 systems.

Download the latest release using wget:

    

        
        
wget https://github.com/arm/arm-toolchain/releases/download/release-22.1.0-ATfE/ATfE-22.1.0-Linux-AArch64.tar.xz

    

Use tar to extract the file:

    

        
        
tar xfJ ATfE-22.1.0-Linux-AArch64.tar.xz -C $HOME

    

Add the ATfE bin directory to your PATH:

    

        
        
export PATH=$HOME/ATfE-22.1.0-Linux-AArch64/bin:$PATH

    

Test the installation

Verify the clang installation

Use the --version option to verify the correct compiler is being invoked:

    

        
        
clang --version

    

The output is similar to:

    

        
        clang version 22.1.0
Target: aarch64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/ubuntu/ATfE-22.1.0-Linux-AArch64/bin
Arm Toolchain ID: E0075 (44010d72)

        
    

Build a sample application with clang

Use a text editor to create an example source file named hello.c with the following code:

    

        
        
#include <stdio.h>

int main()
{
  printf("hello");
  return 0;
}

    

Several compiler options are needed. For more information, see Using the toolchain .

To build for Armv6-M, run:

    

        
        
clang --target=armv6m-none-eabi -fno-exceptions -fno-rtti -lcrt0-semihost -lsemihost -T picolibc.ld -o hello_v6m hello.c

    

To build for Armv7-M, run:

    

        
        
clang --target=armv7m-none-eabi -fno-exceptions -fno-rtti -lcrt0-semihost -lsemihost -T picolibc.ld -o hello_v7m hello.c

    

Run the example applications

The applications can be run on Fixed Virtual Platforms (FVP) .

To run the Armv6-M example on a Cortex-M0 FVP:

    

        
        
FVP_MPS2_Cortex-M0 -a hello_v6m

    

To run the Armv7-M example on a Cortex-M3 FVP:

    

        
        
FVP_MPS2_Cortex-M3 -a hello_v7m

    

The output includes the hello message along with diagnostic output from the FVP:

    

        
        telnetterminal1: Listening for serial connection on port 5000
telnetterminal2: Listening for serial connection on port 5002
telnetterminal0: Listening for serial connection on port 5001
hello
Info: /OSCI/SystemC: Simulation stopped by user.

        
    

You’re now ready to use Arm Toolchain for Embedded.