Encoding

💡 Most users won't need to change the encoding so this section is mainly informative.

defmt data can be encoded using one of these 2 formats:

• rzcobs - Reverse Zero-compressing COBS encoding (rzCOBS). This is the default encoding.
• raw - raw data, that is no encoding.

In comparison to not using any encoding, rzcobs compresses the data (uses less transport bandwidth), and adds some degree of error detection thanks to its use of frames.

The encoding is selected via a Cargo feature on the defmt crate. These Cargo features are named encoding-{encoder_name}, e.g. encoding-rzcobs and encoding-raw.

[package]
name = "my-application"

[dependencies.defmt]
version = "0.3.0"
features = ["encoding-rzcobs"] # <- encoding

⚠️ Note that libraries (dependencies) MUST not select the encoder so that applications (top-level crates) can.

If no enocding-* feature is enabled then the default encoding is used.

The encoding is included in the output binary artifact as metadata so printers will detect it and use the appropriate decoder automatically. When the rzcobs encoding is used the printers will skip malformed frames (decoding errors) and continue decoding the rest of the defmt data. In contrast, printers handling the raw encoding will exit on any decoding error.