Printers are host programs that receive log data, format it and display it. The following printers are currently available:

  • probe-run, parses data sent over RTT (ARM Cortex-M only).

    💡 If you are using the git version of defmt, make sure you also install the tool from git and not

    Since v0.3.3, probe-run has now a --json flag to format the output. The main goal of --json is to produce machine readable output, that can be used to changing the human-readable format, a question addressed here for example.

  • defmt-print, a generic command-line tool that decodes defmt data passed into its standard input.

  • qemu-run, parses data sent by QEMU over semihosting (ARM Cortex-M only).

    💡 Used for internal testing and won't be published to