外文以及翻译-基于单片机的电子琴设计.doc

　　外文资料原文 　　Microcontroller-based design and manufacture（1） MCU 　　A microcontroller （or MCU） is a computer-on-a-chip. It is a type of microprocessoremphasizing self-sufficiency and cost-effectiveness, in contrast to a general-purposemicroprocessor （the kind used in a PC）。 　　The majority of computer systems in use today are embedded in other machinery, such astelephones, clocks, appliances, vehicles, and infrastructure. An embedded system usually hasminimal requirements for memory and program length and may require simple but unusualinput/output systems. For example, most embedded systems lack keyboards, screens, disks,printers, or other recognizable I/O devices of a personal computer. They may control electricmotors, relays or voltages, and read switches, variable resistors or other electronic devices. Often,the only I/O device readable by a human is a single light-emitting diode, and severe cost or powerconstraints can even eliminate that. 　　In contrast to general-purpose CPUs, microcontrollers do not have an address bus or a databus, because they integrate all the RAM and non-volatile memory on the same chip as the CPU. 　　Because they need fewer pins, the chip can be placed in a much smaller, cheaper package. 　　Integrating the memory and other peripherals on a single chip and testing them as a unitincreases the cost of that chip, but often results in decreased net cost of the embedded system as awhole. （Even if the cost of a CPU that has integrated peripherals is slightly more than the cost of aCPU + external peripherals, having fewer chips typically allows a smaller and cheaper circuitboard, and reduces the labor required to assemble and test the circuit board）。 This trend leads todesign. 　　A microcontroller is a single integrated circuit, commonly with the following features: 　　central processing unit - ranging from small and simple 4-bit processors to sophisticated 32-or 64-bit processors 　　input/output interfaces such as serial ports （UARTs）other serial communi