Is There a Future for 8-Bit MCUs？

　　Is There a Future for 8-Bit MCUs？

　　随着越来越多的嵌入式设计迁移到廉价的32位单片机，有点用一个8位的架构，可以追溯到20世纪70年代开始一个新项目吗？

　　最近，两位硅实验室工程师邀请我共进午餐，听取我对“8对32位战争”的看法。我认为32位处理器已经变得如此节能和便宜，现在是时候停止谈论使用35岁的8位8051架构的新设计。不过，原则上，我从不拒绝免费午餐，所以我接受了邀请。结果证明这是一次值得讨论的讨论。

　　Faster or smaller？

　　The primary argument for going to 32 bits is processing speed. A 32-bit MCU can process instructions quickly， enabling CPUs to wake up from a low-power sleep mode， crunch and transmit data， and go back to sleep ASAP. The time spent in active mode is minimized， therefore minimizing overall energy consumption.

　　Modern 32-bit MCUs typically use a pipelined architecture， enabling them to fetch， store， and execute multiple instructions simultaneously; whereas legacy 8-bit 8051s may require multiple clock cycles to execute one instruction. While they can be scaled back， 32-bit MCUs typically operate at high speed in run mode （32 to 100 MHz） while their 8-bit counterparts are slogging along at 4 MHz， or even at the speed of the real-time clock （32.768 kHz）。 Even if they do not always take full advantage of it， 32-bit MCUs are all about speed. For computationally intensive applications， they are the way to go.