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Stack Watermarking

Definition

A technique to measure peak stack usage by filling task stacks with a known pattern (usually 0xA5A5A5A5) at creation time, then scanning backward from the stack end to find how deep the pattern was overwritten. FreeRTOS provides uxTaskGetStackHighWaterMark() for this.

Why it matters

Without stack watermarking, stack sizes are guesses. Undersized stacks silently corrupt adjacent memory. Oversized stacks waste RAM on memory-constrained MCUs.

Relevant MCU families

STM32ESP32nRF52RP2040

Related problems

RTOS Stack Overflow
You picked your stack sizes by guessing. So did everyone. When a task overflows its stack, it silently corrupts adjacent memory. No fault, no warning, just mysterious behavior days later.

Other terms

HardFault HandlerMISRA CDirect Memory Access (DMA)

AI tools that understand stack watermarking

usefirmware's AI is built with deep knowledge of stack watermarking and every other firmware concept. Not a general tool learning firmware on the fly.

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