espflash

A library and command-line tool for flashing Espressif devices.

Supports the ESP32, ESP32-C2/C3/C5/C6, ESP32-H2, ESP32-P4, and ESP32-S2/S3.

Table of Contents

• Installation
• Usage
  • Permissions on Linux
  • Windows Subsystem for Linux
  • Cargo Runner
• Using espflash as a Library
• Configuration Files
  • espflash_ports.toml
  • espflash.toml
  • Configuration Files Location
  • Configuration Precedence
• Logging Format
• Development Kit Support Policy
• License
  • Contribution

Installation

If you are installing espflash from source (ie. using cargo install) then you must have rustc>=1.85.0 installed on your system.

To install:

cargo install espflash --locked

Alternatively, you can use cargo-binstall to download pre-compiled artifacts from the releases and use them instead:

cargo binstall espflash

Usage

A command-line tool for interacting with Espressif devices

Usage: espflash [OPTIONS] <COMMAND>

Commands:
  board-info       Print information about a connected target device
  checksum-md5     Calculate the MD5 checksum of the given region
  completions      Generate completions for the given shell
  erase-flash      Erase Flash entirely
  erase-parts      Erase specified partitions
  erase-region     Erase specified region
  flash            Flash an application in ELF format to a connected target device
  hold-in-reset    Hold the target device in reset
  list-ports       List available serial ports
  monitor          Open the serial monitor without flashing the connected target device
  partition-table  Convert partition tables between CSV and binary format
  read-flash       Read SPI flash content
  reset            Reset the target device
  save-image       Generate a binary application image and save it to a local disk
  write-bin        Write a binary file to a specific address in a target device's flash
  help             Print this message or the help of the given subcommand(s)

Options:
  -S, --skip-update-check  Do not check for updates
  -h, --help               Print help
  -V, --version            Print version

Permissions on Linux

In Linux, when using any of the commands that requires using a serial port, the current user may not have access to serial ports and a "Permission Denied" or "Port doesn’t exist" errors may appear.

On most Linux distributions, the solution is to add the user to the dialout group (check e.g. ls -l /dev/ttyUSB0 to find the group) with a command like sudo usermod -a -G dialout $USER. You can call su - $USER to enable read and write permissions for the serial port without having to log out and back in again.

Check your Linux distribution’s documentation for more information.

Windows Subsystem for Linux

It is not currently possible to use espflash from within WSL1. There are no plans to add support for WSL1 at this time.

It is also not possible to flash chips using the built-in USB_SERIAL_JTAG peripheral when using WSL2, because resetting also resets USB_SERIAL_JTAG peripheral, which then disconnects the chip from WSL2. Chips can be flashed via UART using WSL2, however.

To be able to flash within WSL2, systemd should be enabled. To do so, create or edit /etc/wsl.conf using sudo for admin permissions and add the following:

[boot]
systemd=true

and then close the WSL distribution on Windows side using PowerShell to restart WSL instances:

wsl.exe --shutdown

For more information, please refer here.

Cargo Runner

You can also use espflash as a Cargo runner by adding the following to your project's .cargo/config.toml file, for example:

[target.'cfg(any(target_arch = "riscv32", target_arch = "xtensa"))']
runner = "espflash flash --baud=921600 --monitor /dev/ttyUSB0"

With this configuration you can flash and monitor you application using cargo run.

Using espflash as a Library

espflash can be used as a library in other applications:

espflash = { version = "3.3", default-features = false }

or cargo add espflash --no-default-features

Warning Note that the cli module does not provide SemVer guarantees.

We disable the default-features to opt-out the cli feature, which is enabled by default; you likely will not need any of these types or functions in your application so there’s no use pulling in the extra dependencies.

Configuration Files

There are two configuration files allowing you to define various parameters for your application:

• espflash.toml: Project configuration
• espflash_ports.toml: Port configuration

The reason to split configuration into two different files is to allow Git ignoring the Serial Port configuration, which is specific to the user (see #727).

espflash_ports.toml

This file allows you to define the serial port connection parameters:

• By name:

  [connection]
  serial = "/dev/ttyUSB0"
  

• By USB VID/PID values:

  [[usb_device]]
  vid = "303a"
  pid = "1001"
  

espflash.toml

This file allows you to define different flash parameters:

• Baudrate:

baudrate = 460800

• Bootloader:

bootloader = "path/to/custom/bootloader.bin"

• Partition table

partition_table = "path/to/custom/partition-table.bin"

• Flash settings

[flash]
mode = "qio"
size = "8MB"
frequency = "80MHz"

Configuration Files Location

You can have a local and/or a global configuration file(s):

• For local configurations, store the file under the current working directory or in the parent directory (to support Cargo workspaces) with the name espflash.toml
• Global file location differs based on your operating system:
  • Linux: $HOME/.config/espflash/espflash.toml or $HOME/.config/espflash/espflash_ports.toml
  • macOS: $HOME/Library/Application Support/rs.esp.espflash/espflash.toml or $HOME/Library/Application Support/rs.esp.espflash/espflash_ports.toml
  • Windows: %APPDATA%\esp\espflash\espflash.toml or %APPDATA%\esp\espflash\espflash_ports.toml

Configuration Precedence

1. Environment variables: If ESPFLASH_PORT, MONITOR_BAUD or ESPFLASH_BAUD are set, the will be used instead of the config file value.
2. Local configuration file
3. Global configuration file

Logging Format

espflash flash and monitor subcommands support several logging formats using the -L/--log-format argument:

• serial: Default logging format
• defmt: Uses defmt logging framework. With logging format, logging strings have framing bytes to indicate that they are defmt messages.
  • See defmt section of esp-println readme.
  • For a detailed guide on how to use defmt in the no_std ecosystem, see defmt project of Embedded Rust (no_std) on Espressif book.

Development Kit Support Policy

While in an ideal world we would aim to provide full support for all available development kits, this is unfortunately not achievable in practice. Instead, we aim to ensure full compatibility with all official Espressif development kits.

We do not expect issues with third-party kits, however occasion issues do crop up. When this happens, if users expect fixes to be made then they are expected to debug the issue themselves so that a fix can be formulated; we cannot always reproduce these problems ourselves, and it's not reasonable to expect us to purchase every development kit users may experience issues with.

License

Licensed under either of:

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.