#knurling #logging #logger #formatting #formatter

sys no-std defmt

A highly efficient logging framework that targets resource-constrained devices, like microcontrollers

6 releases

new 0.2.0 Feb 19, 2021
0.1.3 Nov 30, 2020
0.0.0 Aug 14, 2020

#39 in Debugging

Download history 5/week @ 2020-11-04 183/week @ 2020-11-11 137/week @ 2020-11-18 216/week @ 2020-11-25 620/week @ 2020-12-02 895/week @ 2020-12-09 419/week @ 2020-12-16 245/week @ 2020-12-23 542/week @ 2020-12-30 790/week @ 2021-01-06 449/week @ 2021-01-13 411/week @ 2021-01-20 623/week @ 2021-01-27 997/week @ 2021-02-03 1287/week @ 2021-02-10 611/week @ 2021-02-17

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Used in 17 crates (16 directly)




defmt ("de format", short for "deferred formatting") is a highly efficient logging framework that targets resource-constrained devices, like microcontrollers.

The fastest way to get started with defmt is to use our app-template to set up a new Cortex-M embedded project.

For more details about the framework check the book at https://defmt.ferrous-systems.com.

The git version of the defmt book can be viewed at https://defmt-next.ferrous-systems.com/.


defmt is part of the Knurling project, Ferrous Systems' effort at improving tooling used to develop for embedded systems.

If you think that our work is useful, consider sponsoring it via GitHub Sponsors.


Licensed under either of

at your option.


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 licensed as above, without any additional terms or conditions.


~23K SLoC