printf Debugging & Logging

Where does printf go on a chip with no console, and what does it cost? Retargeting output to UART/SWO/RTT (vs slow halting semihosting), intrusiveness, and leveled, deferred, compile-gated logging.

22 min read

In this lesson:

the two embedded printf questions: where does it go? and what does it cost?
retargeting output: UART, SWO/ITM, RTT, semihosting
intrusiveness, and why you don't printf in an ISR or hot path
structured logging: levels, compile-time gating, deferred logging
printf vs GDB, and the footprint/reentrancy gotchas

The oldest debugging tool, print a message, but on bare metal it needs setup and care.

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