Back in high school, I was already obsessed with computer hardware. Whenever manufacturers released new products, I would look them up immediately. I knew the differences between models inside out, and I even loved the exaggerated promotional images used by sellers. My Taobao shopping cart was a training ground for balancing cost and performance, while the PC-building requests of friends and relatives were my bugle call to put that knowledge to use. But the PC market had long since passed its era of rapid growth. High technical barriers and ecosystem monopolies led to product homogenization and very little real innovation, and over time I lost interest. Recently I built a small project with an 8051 microcontroller and, along the way, learned more about the many kinds of microcontrollers now on the market. Their low technical barriers and diverse use cases have produced a wild yet flourishing world of chips, memory, and peripherals, and that let me rediscover the old fun. That, in turn, made me want to build a small project that combines microcontrollers with machine learning.