Lesson 25 MCS-51 电子技术专业英语教程[冯新宇主编][电子教案].pptVIP

《电子技术专业英语教程》 Unit9 Microcomputer Lesson 25 MCS-51 《电子技术专业英语教程》冯新宇 主编 电子工业出版社 Lesson 25 MCS-51 Terminology assembly language 汇编语言，装配语言 crystal 晶振 oscillator amplifier 振荡放大器 special function register 特殊功能寄存器 status register 状态寄存器 purpose register 目的寄存器 data pointer 数据指针 mov operations mov指令操作 The Intel 8051 microcontroller is one of the most popular general purpose microcontrollers in use today. The success of the Intel 8051 spawned a number of clones which are collectively referred to as the MCS-51 family of microcontrollers, which includes chips from vendors such as Atmel, Philips, Infineon, and Texas Instruments. Some of the features that have made the 8051 popular are: 8-bit data bus 16-bit address bus 32 general purposes register each of 8 bits 16 bit timers (usually 2, but may have more, or less). 3 internal and 2 external interrupts. Bit as well as byte addressable RAM area of 16 bytes. Four 8-bit ports, (short models have two 8-bit ports). 16-bit program counter and data pointer Basic Pins PIN 9: PIN 9 is the reset pin which is used reset the microcontroller’s internal registers and ports upon starting up. PINS 18 and 19: The 8051 has a built-in oscillator amplifier hence we need to only connect a crystal at these pins to provide clock pulses to the circuit. PINS 40 and 20: Pins 40 and 20 are VCC and ground respectively. The 8051 chip needs +5V 500mA to function properly, although there are lower powered versions like the Atmel 2051 which is a scaled down version of the 8051 which runs on +3V. PINS 29, 30 and 31: As described in the features of the 8051, this chip contains a built-in flash memory. In order to program this we need to supply a voltage of +12V at pin 31. If external memory is connected then PIN 31, also called EA/VPP, should be connected to ground to indicate the presence of external memory. PIN 30 is called ALE (address latch enable), which is used when multiple memory chips are connected to the controller and only one of