Note: This is a fork of the original serialport-rs project on GitLab. Please note there have been some changes to both the supported targets and which Tier some targets are in, and there may be further changes to this made. Additionally, all relevant issues have been migrated to this repository.

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Introduction

serialport-rs is a general-purpose cross-platform serial port library for Rust. It provides a blocking I/O interface and port enumeration on POSIX and Windows systems.

For async I/O functionality, see the mio-serial and tokio-serial crates.

Overview

The library exposes cross-platform serial port functionality through the SerialPort struct. Additional platform-dependent features can be enabled by importing platform-specific SerialPortExt traits. SerialPort implements the standard Read and Write traits.

Serial enumeration is provided on most platforms. The implementation on Linux using glibc relies on libudev, an external dynamic library that will need to be available on the system the final binary is running on. Enumeration will still be available if this feature is disabled, but won't expose as much information and may return ports that don't exist physically. However this dependency can be removed by disabling the default libudev feature:

$ cargo build --no-default-features

Usage

Listing available ports:

let ports = serialport::available_ports().expect("No ports found!");
for p in ports {
    println!("{}", p.port_name);
}

Opening and configuring a port:

let port = SerialPort::builder()
    .baud_rate(115_200)
    .read_timeout(Duration::from_millis(10))
    .open("/dev/ttyUSB0")
    .expect("Failed to open port");

Writing to a port:

use std::io::Write;

let output = "This is a test. This is only a test.".as_bytes();
port.write(output).expect("Write failed!");

Reading from a port:

use std::io::Read;

let mut serial_buf: Vec<u8> = vec![0; 32];
port.read(serial_buf.as_mut_slice()).expect("Read failed");

Some platforms expose additional functionality, which is accessed by importing the platform-specific extension trait.

let port = SerialPort::builder()
    .baud_rate(115_200)
    .read_timeout(Duration::from_millis(10))
    .open("/dev/ttyUSB0")
    .expect("Failed to open port");

#[cfg(windows)]
use serialport::windows::SerialPortExt;

#[cfg(unix)]
use serialport::posix::SerialPortExt;

Closing a port:

serialport-rs uses the Resource Acquisition Is Initialization (RAII) paradigm and so closing a port is done when the SerialPort object is Droped either implicitly or explicitly using std::mem::drop (std::mem::drop(port)).

Migrating to Version 5

Prior to version 5 of this library, the SerialPort type was a trait, and cross-platform functionality was provided by using Box<dyn SerialPort>. Platform-specific functionality required using the platform-specific structs, COMPort and TTYPort.

In version 5, these types have been unified, with a single SerialPort struct as the only serial port type exposed by the library. Platform-specific functionality is implemented through extension traits, which can be imported when needed on a particular platform, to allow you to call extra functions on the SerialPort struct. Using a struct instead of a trait means you no longer need to Box SerialPort instances, and the extension traits should make it easier to write cross-platform code that only occasionally needs access to platform-specific features.

For example, to send a break on a TTY port, in version 4 and earlier, you would have to use the TTYPort struct instead of the cross-platform dyn SerialPort:

use serialport::BreakDuration;

let port = serialport::new("/dev/ttyUSB0", 9600).open_native()?;
port.send_break(BreakDuration::Short)?;

In version 5, you can now use the common SerialPort type everywhere, and to gain access to the platform-specific send_break method, you just have to import the platform-specific trait.

use serialport::posix::{SerialPortExt, BreakDuration};
use serialport::SerialPort;

let port = SerialPort::builder().open("/dev/ttyUSB0")?;
port.send_break(BreakDuration::Short)?;

One other consequence of the switch to a having SerialPort as a struct rather than a trait is that you will now need to import std::io::Read and std::io::Write traits explicitly. Previously, the SerialPort trait inherited from Read and Write so you could call read and write without importing them whenever the SerialPort trait was in scope. With SerialPort as a struct, you now need to explicitly import Read and Write.

Examples

There are several included examples, which help demonstrate the functionality of this library and can help debug software or hardware errors.

• clear_input_buffer - Demonstrates querying and clearing the driver input buffer
• clear_output_buffer - Demonstrates querying and clearing the driver output buffer
• duplex - Tests that a port can be successfully cloned.
• hardware_check - Checks port/driver functionality for a single port or a pair of ports connected to each other.
• list_ports - Lists available serial ports.
• pseudo_terminal - Unix only. Tests that a pseudo-terminal pair can be created.
• receive_data - Output data received on a port.
• transmit - Transmits data regularly on a port with various port configurations. Useful for debugging.

Dependencies

Rust versions 1.46.0 and higher are supported.

For GNU Linux pkg-config headers are required:

• Ubuntu: sudo apt install pkg-config
• Fedora: sudo dnf install pkgconf-pkg-config

For other distros they may provide pkg-config through the pkgconf package instead.

For GNU Linux libudev headers are required as well (unless you disable the default libudev feature):

• Ubuntu: sudo apt install libudev-dev
• Fedora: sudo dnf install systemd-devel

Platform Support

Platform support is broken into two tiers:

• Tier 1 - Builds and tests for this target are run in CI. Failures of either block the inclusion of new code.
• Tier 2 - Builds for this target are run in CI. Tests are not run in CI.

Tier 1:

• Linux
  • i686-unknown-linux-gnu
  • i686-unknown-linux-musl
  • x86_64-unknown-linux-gnu
  • x86_64-unknown-linux-musl
• MacOS/iOS
  • aarch64-apple-darwin
  • x86_64-apple-darwin
• Windows
  • i686-pc-windows-gnu
  • i686-pc-windows-msvc
  • x86_64-pc-windows-gnu
  • x86_64-pc-windows-msvc

Tier 2:

• Android
  • aarch64-linux-android (no serial enumeration)
  • arm-linux-androideabi (no serial enumeration)
  • armv7-linux-androideabi (no serial enumeration)
  • i686-linux-android (no serial enumeration)
  • x86_64-linux-android (no serial enumeration)
• FreeBSD
  • i686-unknown-freebsd
  • x86_64-unknown-freebsd
• Linux
  • aarch64-unknown-linux-gnu
  • aarch64-unknown-linux-musl
  • arm-unknown-linux-gnueabi
  • arm-unknown-linux-gnueabihf
  • arm-unknown-linux-musleabi
  • armv5te-unknown-linux-gnueabi
  • armv5te-unknown-linux-musleabi
  • armv7-unknown-linux-gnueabihf
  • armv7-unknown-linux-musleabihf
  • i586-unknown-linux-gnu
  • i586-unknown-linux-musl
  • mips-unknown-linux-gnu
  • mips-unknown-linux-musl
  • mips64-unknown-linux-gnuabi64
  • mips64el-unknown-linux-gnuabi64
  • mipsel-unknown-linux-gnu
  • mipsel-unknown-linux-musl
  • powerpc-unknown-linux-gnu
  • powerpc64-unknown-linux-gnu
  • powerpc64le-unknown-linux-gnu
  • s390x-unknown-linux-gnu
  • sparc64-unknown-linux-gnu
• MacOS/iOS
  • aarch64-apple-ios
  • x86_64-apple-ios
• NetBSD
  • x86_64-unknown-netbsd (no serial enumeration)

Hardware Support

This library has been developed to support all serial port devices across all supported platforms. To determine how well your platform is supported, please run the hardware_check example provided with this library. It will test the driver to confirm that all possible settings are supported for a port. Additionally, it will test that data transmission is correct for those settings if you have two ports physically configured to communicate. If you experience problems with your devices, please file a bug and identify the hardware, OS, and driver in use.

Known issues:

Licensing

Licensed under the Mozilla Public License, version 2.0.

Contributing

Please open an issue or merge request on GitLab to contibute. Code contributions submitted for inclusion in the work by you, as defined in the MPL2.0 license, shall be licensed as the above without any additional terms or conditions.

Acknowledgments

Special thanks to dcuddeback, willem66745, and apoloval who wrote the original serial-rs library which this library heavily borrows from.

Additional thanks to susurrus and all other contributors to the original serialport-rs project on GitLab.