otampy 2.0.1

Serial OTA application firmware update solution for MicroPython

OTAmpy — Over-The-Air Update Suite for MicroPython

OTAmpy is a lightweight Over-The-Air (OTA) file and system management suite for MicroPython microcontrollers (Raspberry Pi Pico, ESP32, ESP8266, and compatible boards). It provides robust remote firmware updates and device control over wireless serial modules (such as XBee) or any transparent UART connection.

OTAmpy is built on top of the Universal Reliable Serial Transport (URST) protocol, which guarantees error-free framing, integrity checking, and automatic recovery even over noisy or high-latency wireless links.

DISCLAIMER This is not intended as professional grade OTA. Use at your own risk.

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Features

• Transactional OTA firmware updates — files are staged, SHA-256 verified, and atomically committed; a failed transfer leaves the running firmware untouched.
• Interactive file management — upload (cp, upd), view (cat), or remove (rm) files on the device.
• Recovery protection — rm refuses to delete boot, main, configuration, OTAmpy, or URST files needed for future wireless maintenance; no force option exists.
• Remote reboot and reset — trigger a hard reboot (rb) or MicroPython soft reset (sr) over the air.
• Diagnostic commands — ping health checks and mem RAM/flash queries.
• Port management — ports lists and selects adapters; OTAMPY_PORT and persistent ~/.config/otampy/config.json settings avoid repeating --port on every command.
• Target-matched bytecode deployment — --bytecode compiles OTAmpy and URST to .mpy using the connected device's exact .mpy format and small-int width.
• Fail-safe CLI — destructive commands display a confirmation prompt before contacting the device.

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Repository Structure

otampy/
├── src/otampy/           # Host CLI package (Python ≥ 3.12)
│   ├── cli.py            # Click-based command-line interface
│   ├── deploy.py         # Deploy command implementation
│   └── device/           # MicroPython device library (bundled in releases)
│       ├── lib/otampy/   # Device-side OTA library
│       └── examples/     # Example boot.py, main.py, config files
├── docs/                 # Deployment, release, architecture, and protocol guides
├── tests/                # Host-side pytest suite
└── scripts/              # Automated release gate

The published package contains both the CLI and a read-only copy of the device library. The canonical device source lives in src/otampy/device/; see the deployment guide for how it is bundled.

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Installation

Assumes your project will be using UV

uv add otampy
otampy init
# Edit configota.py

During development you can use pipx install git+https://github.com/simonl65/otampy.git@develop --force to install the latest development version.

init creates boot.py, main.py, and configota.py in your project at the location (device-dir) of your choosing. Edit configota.py to set the UART pins, baud rate, and timeout for your board. init will not overwrite existing files but will prompt you; use --force only when intentionally replacing all three.

Preview then perform the initial USB deployment:

WARNING
deploy erases the device filesystem before copying files. Back up any application data and configuration first.

# Edit configota.py before deployment
otampy deploy --port /dev/ttyACM0 --dry-run
otampy deploy --port /dev/ttyACM0

The installed package contains the versioned OTAmpy device library and the templates used by init. Your project owns boot.py, main.py, and configota.py; upgrading the package does not overwrite them.

Developer installation from this repository

Ensure uv is installed, then:

cd /path/to/otampy
uv sync
uv tool install -e .

Device library setup (repository checkout)

1. Copy src/otampy/device/examples/config.example.py to src/otampy/device/examples/configota.py (do not rename) and set the UART pins and baud rate for your board.

2. Deploy the device library, example scripts, and URST to your device:

   otampy deploy --port /dev/ttyACM0
   

3. Optionally add --with-logger to install the log-to-file development logger. The default profile runs silently via NullLogger.

4. For a smaller, target-matched deployment, install mpy-cross and pass --bytecode. OTAmpy queries the connected firmware's .mpy format before erasing anything.

   uv tool install mpy-cross
   otampy deploy --port /dev/ttyACM0 --bytecode
   

5. Call ota.poll() inside your application main loop to enable background OTA listening.

See the deployment guide and device integration guide for the complete set of deployment options, logger injection, and integration examples.

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Usage

All commands follow this pattern:

otampy [global-options] <command> [command-options]

Global options

Option	Description
-p, --port PORT	Select the OTA UART adapter (e.g. /dev/ttyUSB0, COM3).
-b, --baud RATE	Set the baud rate.
--log-level LEVEL	Host CLI logging: DEBUG, INFO, WARNING, ERROR, or CRITICAL.

The default log level is ERROR. When --log-level is supplied, the CLI offers to retain the setting permanently (p), for the current shell session (s), or only for the current command (c).

Permanent port and log-level settings are stored together in ~/.config/otampy/config.json:

{
  "default_port": "/dev/ttyUSB0",
  "log_level": "DEBUG"
}

Session-only selections use shell-specific files in the operating system's temporary directory (normally /tmp on Linux) and do not alter the permanent configuration. OTAMPY_PORT and OTAMPY_LOG_LEVEL environment variables override saved settings.

Commands

Command	Arguments	Description
cat	file	Print a file from the device.
cp	source[:dest] [...]	Copy files or folders to the device without rebooting.
deploy	(see below)	Erase and deploy the full device library over USB.
device-dir	—	Show or manage the saved project directory for deploy.
init	[directory]	Scaffold boot.py, main.py, and configota.py.
log-level		Show or manage the saved CLI log level.
ls	[path]	List device directory contents.
mem	—	Query device RAM and flash utilisation.
ping	—	Connection health check - should receive PONG.
ports	—	List available serial adapters; mark and store a selection.
rb	—	Hard reboot the device (with confirmation).
rm	path [...]	Remove paths from the device (with confirmation - not recoverable).
sr	—	MicroPython soft reset (with confirmation).
upd	[source[:dest] ...]	Transactional OTA firmware update.1

¹ Updates take place after the device has rebooted; the update process is handled by boot.py. With no sources specified, upd selects main.py and all Python files under lib/ in the current directory.

Deployment Options

Option	Effect
-p, --port	Select the USB/serial device used by mpremote.
--device-dir	Select the directory containing device/ (boot.py, etc.)
--with-logger	Install the optional log-to-file package.
--bytecode, --mpy	Compile OTAmpy and URST into target-matched .mpy files.
--mpy-cross	Select the mpy-cross executable or command.
--no-mip	Install neither URST nor the optional logger.
--no-reset	Leave the board without a final reset.
--dry-run	Print the complete mpremote command without running it.
--mpremote	Use a specific mpremote executable.

Common examples

Select a port for subsequent commands (avoids repeating --port):

otampy ports

NOTE: The following commands assume you've set the port.

Check device connection health:

otampy ping

List device files:

otampy ls
otampy ls /lib

Query device memory and storage:

otampy mem

Copy files or folders to the device (without reboot):

otampy cp settings.json:config/settings.json
otampy cp assets:assets/
otampy cp 'device/lib/*:lib/'

cp accepts multiple sources, folders, and local wildcard patterns (*, ?, [], **). Folder contents are copied recursively; empty folders are not created. Files are streamed to checksum-verified staging files and committed individually while the device continues running. Copies targeting root /boot.py or /main.py produce a reminder that the replacement will take effect on the next restart.

Remove files or directories (recovery paths are protected):

otampy rm old.py config.old
otampy rm 'lib/plugins/*.py'

Quote wildcards to prevent the host shell from expanding them locally (e.g., otampy rm '*'). Prefix an argument with : (e.g., :notes.txt) or use --literal-remote-paths if the filename also exists locally to prevent protection/verification aborts. Removing a non-empty directory requires a confirmation prompt.

To preserve remote recovery, rm cannot remove root /boot.py, /main.py, /configota.py, anything under /lib/otampy or /lib/urst, or an ancestor such as /lib or /.

Trigger an OTA firmware update (defaults to main.py and all lib/ Python files):

otampy upd

Update specific files or mapped paths:

otampy upd main.py configota.py
otampy upd 'device/lib/something/*.py:lib/something/'

Directories include all Python files recursively. Local *, ?, [], and ** patterns are supported. A pattern matching multiple files must map to a destination ending in /. If any source or pattern has no matches, the update stops before contacting the device.

Enable host-side diagnostics for a single command:

otampy --log-level DEBUG ping

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Device Integration

Call ota.poll() in your application loop:

from otampy import OTA
from machine import UART

uart = UART(1, baudrate=9600, tx=Pin(4), rx=Pin(5))
ota = OTA(uart, config=config)

while True:
    ota.poll()
    # ... application logic

Important! - If your device needs to be set to a safe state before a reboot/reset you can add a callback function to the ota.poll() call:

def prepare_for_shutdown():
    # ... application safety logic

while True:
    ota.poll(callback=prepare_for_shutdown)
    # ... application logic

This will invoke prepare_for_shutdown() before continuing to reboot/reset.

Inject any logger that implements debug, info, warning, error, and critical:

from log_to_file import Logger
from otampy import OTA

logger = Logger("/logs/ota.log", "some identifier", level="DEBUG")
ota = OTA(uart, config=config, logger=logger)

When no logger is provided, OTA uses an allocation-light NullLogger. NullLogger is also importable directly for applications that want an unconditional logger variable:

from otampy import NullLogger
logger = NullLogger()

See the device integration guide for the full configuration reference.

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Contributing

Contributions are welcome. Please follow the process below to keep the codebase consistent and the release gate green.

Getting started

1. Fork the repository and create a feature branch from develop:

   git checkout develop
   git checkout -b feature/your-feature-name
   

2. Install the development dependencies:

   uv sync --group dev
   

3. Make your changes. Match the existing code style; the project uses Ruff for linting and formatting.

Running tests

uv run pytest

The test suite requires no connected hardware. Coverage is reported automatically.

Run the linter:

uv run ruff check .
uv run ruff format --check .

Submitting a pull request

• Target the develop branch, not main.
• Ensure ruff check and pytest both pass before opening a PR.
• Describe what the change does, why it is needed, and how it was tested.
• For changes to the device library, note any impact on flash or RAM footprint.
• Keep commits focused and write clear, semantic and scoped commit messages (e.g. feat(core): add ability to walk on water).

Reporting issues

Open a GitHub issue and include:

• A minimal reproduction case.
• The host OS, Python version, and OTAmpy version (otampy --version).
• The target board, MicroPython version, and transport (XBee model, direct UART, etc.).
• Any relevant host CLI and/or device logs (For CLI use: --log-level DEBUG. For device set LOG_LEVEL="DEBUG" in configota.py).

Release process

Releases are cut by maintainers using the automated gate described in the release guide. Do not build publishable artifacts manually.

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Documentation

Document	Description
Deployment guide	All deploy options, logging profiles, and bytecode deployment.
Device integration guide	Device-side setup, logger injection, and runtime file copy.
Protocol specification	URST framing, packet types, and error recovery.
Architecture overview	Component relationships and design decisions.
Release guide	Versioning, the automated release gate, and publishing.

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License

OTAmpy is released under the Sustainable Use License.

Non-commercial and internal business use is permitted free of charge. Commercial redistribution or monetisation requires a separate commercial licence. Contact [e-mail] for commercial licensing enquiries.