Adding Timestamps to Captured defmt Output

[nan-mu]

I am conceptualizing a feature, and before raising an issue, I want to ensure I am not overlooking anything. Is it possible for espflash to capture defmt output and prepend a host-side timestamp before outputting to the console instead of using the MCU's time? This could help developers verify that time-related code is functioning correctly. I am unsure if this feature already exists, as I have perused most of the relevant documentation without finding a description of such functionality.

[Vollbrecht]

defmt is usually transported over rtt connected to a debugger. In other cases, like in espflash monitor case, its possible but does not work out of the box, because the transport layer is different ( e.g uart / serial). So the defmt messages that you are sending need to be framed, such that espflash monitor can decode them.

With framing out of the way you then can send any arbitrary defmt message over it. If you want to include the timestamps defmt logging implementation on your MCU can generate and send it to espflash the same way as it is sending to for example probe-rs. So in that regard there is nothing to do on espflash sites, besides different formatting options for a defmt message.

[nan-mu]

I'm not looking at the code right now; I want to know if espflash directly links the output to the console? I think this can be unrelated to the microcontroller's content. Do you mean that espflash doesn't capture the output from the serial port?

[Vollbrecht]

What do you mean by "links the output to the console"? espflash monitor reads the uart/serial output, then try's to interpret it by looking if it received a defmt message or some regular uart/serial stuff that is send for example from the bootloader or output of a backtrace for example. It then potentially decodes it depending on the output and print it to the terminal.

[nan-mu]

Please understand that I am not a native English speaker. What I mean is, after configuration, espflash will prepend each defmt output with a system timestamp, similar to how we specify output formats in std programming. However, this time the timestamp is provided by espflash rather than the MCU.

For example, our current output is like this:

DEBUG - xxxxxxx

After enabling this feature, it becomes:

DEBUG - yy:mm:dd hh:mm:ss - xxxxxxx

Based on your description, this seems relatively easy to implement? I'm willing to contribute some code.