Firmware glossary

Essential embedded systems terminology, explained for working firmware engineers.

Stack Watermarking

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.

HardFault Handler

The ARM Cortex-M exception handler invoked when the processor detects a fatal error — illegal memory access, divide by zero, undefined instruction, or bus fault. The default implementation is an infinite loop (while(1){}) that provides zero diagnostic information.

MISRA C

A set of coding guidelines for the C language developed by the Motor Industry Software Reliability Association. Defines required and advisory rules to prevent undefined behavior, improve code safety, and ensure portability in safety-critical embedded systems.

Direct Memory Access (DMA)

A hardware peripheral that transfers data between memory regions or between peripherals and memory without CPU intervention. Frees the CPU to do other work during bulk transfers (ADC sampling, UART RX, SPI communication).