Q: What are the differences between STM32 HAL and LL drivers and when to use each?
Answer
HAL (Hardware Abstraction Layer) provides high-level APIs with full peripheral initialization interrupt handling and timeout management – ideal for rapid development. LL (Low Layer) drivers provide direct register access with minimal overhead. Use HAL for: complex peripherals (USB SDMMC ETH) projects with tight deadlines or when portability matters. Use LL for: timing-critical code (PWM at >100 kHz sub-us interrupts) power-constrained battery devices. Mixed usage is supported. LL drivers are not reentrant if used incorrectly – be careful in RTOS environments.
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