Is There a Future for 8-Bit MCUs？

　　隨著越來越多的嵌入式設(shè)計遷移到廉價的32位單片機(jī)，有點用一個8位的架構(gòu)，可以追溯到20世紀(jì)70年代開始一個新項目嗎？

　　最近，兩位硅實驗室工程師邀請我共進(jìn)午餐，聽取我對“8對32位戰(zhàn)爭”的看法。我認(rèn)為32位處理器已經(jīng)變得如此節(jié)能和便宜，現(xiàn)在是時候停止談?wù)撌褂?5歲的8位8051架構(gòu)的新設(shè)計。不過，原則上，我從不拒絕免費午餐，所以我接受了邀請。結(jié)果證明這是一次值得討論的討論。

　　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.