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ツール

マイクロコントローラを扱う際は、いくつかの異なるツールを利用することになります。あなたのノートPCとは異なるアーキテクチャを扱うことになるでしょうし、リモートデバイス上でプログラムを実行しデバッグする必要があります。

下記リストのツールを利用します。最小バージョンが指定されていない場合、新しいバージョンであれば機能するはずです。私たちがテストしたバージョンをリストに示しています。

  • ARM Cortex-Mコンパイルサポートを追加したRust 1.31、1.31-beta以上のツールチェイン。
  • cargo-binutils~0.1.4
  • qemu-system-arm。テストしたバージョン: 3.0.0
  • OpenOCD >=0.8.テストしたバージョン: v0.9.0とv0.10.0
  • ARMサポートのGDB。バージョン7.12以上を強く推奨。テストしたバージョン: 7.10、7.11、7.12、8.1
  • [任意] gitまたはcargo-generate。どちらもインストールしていないのであれば、どちらをインストールしてもかまいません。

下記に、なぜこれらのツールを利用するのか、を説明します。インストール方法は、次のページにあります。

cargo-generateかgit

ベアメタルプログラムは、非標準 (no_std)なRustプログラムであり、プログラムのメモリレイアウトを正しくするために、リンクプロセスをいじる必要があります。 これには、独特なファイル(リンカスクリプトなど)と設定(リンカフラグ)が必要です。 プロジェクト名やターゲットハードウェアの特徴などを、空白に入力するだけで済むように、テンプレートを用意しています。

このテンプレートは、cargo-generateとの互換性があります。cargo-generateは、テンプレートからCargoプロジェクトを作成するためのCargoのサブコマンドです。 このテンプレートは、gitやcurl、wget、ウェブブラウザを使ってダウンロードできます。

cargo-binutils

cargo-binutilsは、Rustツールチェインとともに配布されているLLVMツールを簡単に使うためのCargoサブコマンド一式です。 これらのツールは、LLVMのobjdumpやnm、sizeを含んでおり、バイナリを調査するために使われます。

GNU binutilsではなく、これらのツールを利用する利点は次の通りです。 (a) LLVMツールのインストールは、OSに関わらず、共通のコマンド1つ(cmd)で済みます。 (b) objdumpなどのツールは、rustcがサポートする全てのアーキテクチャ(ARMからx86_64まで)をサポートします。これは、同じLLVMバックエンドを共有しているためです。

qemu-system-arm

QEMUはエミュレータです。今回は、ARMシステムを完全にエミュレートできるものを使います。 私たちは、ホスト上で組込みプログラムを実行するためにQEMUを利用します。 このおかげで、ハードウェアを持っていなくても、この本のいくつかの部分を試すことができます。

Tooling for Embedded Rust Debugging

Overview

Debugging embedded systems in Rust requires specialized tools including software to manage the debugging process, debuggers to inspect and control program execution, and hardware probes to facilitate interaction between the host and the embedded device. This document outlines essential software tools like Probe-rs and OpenOCD, which simplify and support the debugging process, alongside prominent debuggers such as GDB and the Probe-rs Visual Studio Code extension. Additionally, it covers key hardware probes such as Rusty-probe, ST-Link, J-Link, and MCU-Link, which are integral for effective debugging and programming of embedded devices.

Software that drives debugging tools

Probe-rs

Probe-rs is a modern, Rust-focused software designed to work with debuggers in embedded systems. Unlike OpenOCD, Probe-rs is built with simplicity in mind and aims to reduce the configuration burden often found in other debugging solutions. It supports various probes and targets, providing a high-level interface for interacting with embedded hardware. Probe-rs integrates directly with Rust tooling, and integrates with Visual Studio Code through its extension, allowing developers to streamline their debugging workflow.

OpenOCD (Open On-Chip Debugger)

OpenOCD is an open-source software tool used for debugging, testing, and programming embedded systems. It provides an interface between the host system and embedded hardware, supporting various transport layers like JTAG and SWD (Serial Wire Debug). OpenOCD integrates with GDB, which is a debugger. OpenOCD is widely supported, with extensive documentation and a large community, but may require complex configuration, especially for custom embedded setups.

Debuggers

A debugger allows developers to inspect and control the execution of a program in order to identify and correct errors or bugs. It provides functionalities such as setting breakpoints, stepping through code line by line, and examining the values of variables and memory states. Debuggers are essential for thorough software development and maintenance, enabling developers to ensure that their code behaves as intended under various conditions.

Debuggers know how to:

  • Interact with the memory mapped registers.
  • Set Breakpoints/Watchpoints.
  • Read and write to the memory mapped registers.
  • Detect when the MCU has been halted for a debug event.
  • Continue MCU execution after a debug event has been encountered.
  • Erase and write to the microcontroller’s FLASH.

Probe-rs Visual Studio Code Extension

Probe-rs has a Visual Studio Code extension, providing a seamless debugging experience without extensive setup. Through this connection, developers can use Rust-specific features like pretty printing and detailed error messages, ensuring that their debugging process aligns with the Rust ecosystem.

TRACE32

TRACE32 is a professional debugging and tracing solution developed by Lauterbach for embedded systems. It supports a wide range of processor architectures, including ARM and RISC-V, and connects to target hardware via JTAG, SWD, and various trace interfaces. TRACE32 provides advanced debugging capabilities such as multicore debugging, complex breakpoints, and real-time trace analysis. It works with standard ELF/DWARF debug information, making it compatible with Rust binaries built using conventional toolchains.

GDB (GNU Debugger)

GDB is a versatile debugging tool that allows developers to examine the state of programs while they run or after they crash. For embedded Rust, GDB connects to the target system via OpenOCD or other debugging servers to interact with the embedded code. GDB is highly configurable and supports features like remote debugging, variable inspection, and conditional breakpoints. It can be used on a variety of platforms, and has extensive support for Rust-specific debugging needs, such as pretty printing and integration with IDEs.

Probes

A hardware probe is a device used in the development and debugging of embedded systems to facilitate communication between a host computer and the target embedded device. It typically supports protocols like JTAG or SWD, enabling it to program, debug, and analyze the microcontroller or microprocessor on the embedded system. Hardware probes are crucial for developers to set breakpoints, step through code, and inspect memory and processor registers, effectively allowing them to diagnose and fix issues in real-time.

Rusty-probe

Rusty-probe is an open-sourced USB-based hardware debugging probe designed to work with probe-rs. The combination of Rusty-Probe and probe-rs provides an easy-to-use, cost-effective solution for developers working with embedded Rust applications.

ST-Link

The ST-Link is a popular debugging and programming probe developed by STMicroelectronics primarily for their STM32 and STM8 microcontroller series. It supports both debugging and programming via JTAG or SWD (Serial Wire Debug) interfaces. ST-Link is widely used due to its direct support from STMicroelectronics’ extensive range of development boards and its integration into major IDEs, making it a convenient choice for developers working with STM microcontrollers.

J-Link

J-Link, developed by SEGGER Microcontroller, is a robust and versatile debugger supporting a wide range of CPU cores and devices beyond just ARM, such as RISC-V. Known for its high performance and reliability, J-Link supports various communication interfaces, including JTAG, SWD, and fine-pitch JTAG interfaces. It is favored for its advanced features like unlimited breakpoints in flash memory and its compatibility with a multitude of development environments.

MCU-Link

MCU-Link is a debugging probe that also functions as a programmer, provided by NXP Semiconductors. It supports a variety of ARM Cortex microcontrollers and interfaces seamlessly with development tools like MCUXpresso IDE. MCU-Link is particularly notable for its versatility and affordability, making it an accessible option for hobbyists, educators, and professional developers alike.