mcumgr-toolkit 0.9.0

Python API for Zephyr's MCUmgr protocol

MCUmgr Client for Zephyr

This library provides a Rust-based Python API for Zephyr's MCUmgr protocol.

It might be compatible with other MCUmgr/SMP-based systems, but it is developed with Zephyr in mind.

Its primary design goals are:

• Completeness
  • cover all use cases of Zephyr's MCUmgr
  • for implementation progress, see this tracking issue
• Performance
  • use static memory and large buffers to prioritize performance over memory footprint
  • see further down for more information regarding performance optimizations required on Zephyr side

Usage Example

Connect to a serial port:

from mcumgr_toolkit import MCUmgrClient

with MCUmgrClient.serial("/dev/ttyACM0") as client:
    client.use_auto_frame_size()

    print(client.os_echo("Hello world!"))

Hello world!

Or a USB-based serial port:

from mcumgr_toolkit import MCUmgrClient

with MCUmgrClient.usb_serial("2fe3:0004") as client:
    client.use_auto_frame_size()

    print(client.os_echo("Hello world!"))

Hello world!

For more information, take a look at the API reference.

Performance

Zephyr's default buffer sizes are quite small and reduce the read/write performance drastically.

The central most important setting is MCUMGR_TRANSPORT_NETBUF_SIZE. Its default of 384 bytes is very limiting, both for performance and as cutoff for large responses, like os_task_statistics() or some shell commands.

Be aware that changing this value also requires an increase of MCUMGR_TRANSPORT_WORKQUEUE_STACK_SIZE to prevent overflow crashes.

In practice, I found that the following values work quite well (on i.MX RT1060) and give me 410 KB/s read and 120 KB/s write throughput, which is an order of magnitude faster than the default settings.

CONFIG_MCUMGR_TRANSPORT_NETBUF_SIZE=4096
CONFIG_MCUMGR_TRANSPORT_WORKQUEUE_STACK_SIZE=8192

If the experience differs on other chips, please open an issue and let me know.

Contributions

Contributions are welcome!

I primarily wrote this crate for myself, so any ideas for improvements are greatly appreciated.