Designing a HAL That Doesn't Lock You In
Every embedded engineer has lived through this moment: your company’s chip supplier emails you that the MCU you designed around is end-of-life, or lead times just jumped to 52 weeks. You stare at 40,000 lines of firmware that call HAL_SPI_Transmit() in 200 places, and you realize your “abstraction” was just ST’s abstraction. You’re locked in. I’ve spent years writing the mid-layer software that sits between customer applications and firmware — the abstraction that’s supposed to make hardware swappable. I’ve seen what works, what doesn’t, and what looks elegant in a conference talk but falls apart when you actually need to port to a different silicon vendor. This post is the guide I wish I’d had five years ago. ...