BentlyNevada330101-00-12-10-02-00PIC系列8位单片机为适应各种不同的用途，有多种型号可供选用。但是，尽管PIC单片机有不同的档次和型号，但其最基本的组成则大同小异。因此，在这里先从型号PIC16F84的单片机入手，讨论其基本组成。PIC16F84是双列直插式(DIP)塑料封装，最大时钟频率可达4MHz。现为Microchip公司的独家产品。PIC16F84单片机的引脚排列可参阅16F8X系列简介一文。本文的附图是该器件的主要组成部分。PIC16F84虽然体积不大，但仍然是一个完整的计算机，它有一个中央处理器(CPU)、程序存储器(ROM)、数据寄存器(RAM)和两个输入/输出口(I/O口)。和其它品种的单片机一样，CPU是此单片机的“首脑”，它从程序存储器中读取和执行指令。在取指和执行时，还可同时对数据寄存器进行取数(前已介绍PIC16F84采用哈佛结构)。由附图可明显看出，程序存储器和数据存储器各有一条总线与CPU相连。有些CPU将CPU内部的寄存器与其外部的RAM是分开管理的，但PIC单片机不是这样，它的通用数据RAM也归为寄存器，称为File寄存器。在PC16F84中，有68个字节的通用RAM，其地址为0CH～4FH。除了通用数据寄存器外，还有一些专用寄存器，其中最常用的工作寄存器为“W寄存器”。CPU将工作数据存放在W寄存器中。寄存器W的作用与其它单片机中的“累加器A”相似。此外，还有几个专用寄存器，它们分别以某种方式控制PIC的运作。PIC16F84的程序存储器是由Flash(闪速)EPROM构成，它可用电来记录和擦除，而在断电时，仍可保留其内容。PIC单片机有些型号的程序存储器用的是EPROM，需要用紫外线来擦除;还有一些型号是一次性可编程(OTP)的产品(一经编程便不能再擦除)。PIC16F84有两个输入/输出口，即A口和B口。每个口的每个引脚可单独设定为输入或输出。各个口的位是从0开始编号的。当A口为输出方式时，其第4位(即RA4)为开路集电极(或开路漏极)输出，而B口及A口其它各位为常规的全CMOS驱动电路。这些功能必须注意，否则会在编程时出错。CPU对每个端口都按一个字节8位来处理，但A口只有5位引脚。PIC输入与COMS兼容，所以PIC输出可驱动TTL或CMOS逻辑芯片。每个输出引脚可以流出或吸入20mA电流，即使一次只用了一个引脚亦是如此。PIC16F84还有一些其它功能，如用来长期存放数据的EEPROM、定时器/计数器模块等，这里也暂不讨论。型号3150-MCM1756-CNB/D1756-CNB/E1756-IV32103003276-6591IC693MDL940IC697ALG230E140CPS2140048086ES7416-3FR05-0AB0R160530431BL210DO242/ATM240/A140DDI8410011BRW-300-FCM3615T140ACI03000140ARI03010140CPS12420140DA175300140DAO85300RVT6-1/5A6FC5548-0AC11-0AA0CH-1290CS8321SCDCS8321SCDSM17/35-TASPM75-TBEEA-PAM-535-A-3216413-15P0973JP6DD1681-0AH21756-L55M14HCS02.1E-W0012-A-03-NNNNVMIVME-7750ECA244-0A244ECE243-1E243ECNT43-0NT43ECPA42-0PA42ECPNC3-0PNC3HCMCIF-0MCIFHCMCO3MC-1AMCO3MCDBG11B-08MDS60A-0015-5A3-4-00MDS60A0040-5A3-4-00VLT5008103003276-65911755KPMPP170092-01939-00FVR008E7S-21746-IB161746-N141746-N181746-NO4V1746-OW161747-L532XCMD2145L13GQA091501-ASA140ACO13000140CHS11000140CPS11100140CPS11420140CPS12420140CPU11303140CRA93101140CRP93100140DDI35300140DDO35300490NAA27103990NAD230001784-PCICA02B-0280-B5026SC6508-4AA02PCI44513703E42101747-OCEEEBA1747-OCS92MARCHAP-10006AV6545-OAG10-0AX0PWS920S-LEDPCI44516ES7-972-0AA02-0XA0PC-E984-78535670AICSA04B5ROD426BA06B-0243-B100MDX61B-0030-5A3-4-00MDX61B-0055-5A3-4-00MDX61B-0075-5A3-4-00KE3000608830162VM31006087501091756-EN2T1756-ENBT1756-L611756-PB7255-MD2PC12-0A6ES7214-2BD23-0XB86ES7223-1PL22-0XA86RA7025-6DV62-06RA7081-6DV62-06RX1700-0AS00CI810BIC693BEM331IC693CMM321IC693CPU360IC693MDL655IC693MDL940R48-1800A140ACI04000140ARI03010140CPS11100140CRA93100140CRP93100140ACI04000140ACO02000140ARI03010140CPS11420140CPU65260140CRA93200140CRP93200140DAI75300140DDO35300PTQ-PDPMV1TDM1.2-100-300-W1A06B-6088-H222#H500140ACI03000140ARI03010140CPS12420140DAI75300140DAO853006ES7321-IBL00-0AA06ES7322-1HH01-0AA06ES7331-7KF02-0AB06ES7338-4BC01-0AB06GK7343-1EX11-0XE0BMXCPS2000BMXDDI1602BMXDDO1602IC697BEM731IC697CHS790IC697CMM711IC697CMM742IC697CPM790IC697PWR711RLM01TK-FTEB01TK-IOLI01TK-PPD011FXM5C1801DO810EI813FFI820FFI830FTU8101756-ENBT/A1756-IF16/A1756-L611756-OB32/A1756-OF81756-PA72/C140AVI03000140CPU11303140CRA93100140CRP93100140DAI74000SM221SM2221746-A131746-C161746-IB321746-NI81746-NO8I1746-OB321746-P41747-L5521756-IF161756-L611756-OB321756-OF8AX521CPUPM571TB511-ETHSV055IGX-45PY59JY1095PY59JY11073126-6R6SC6111-2AA001747-L5518901-457P0970WV6SN1123-1AA00-0DA16DD1661-0AE16DD1661-OAD16ES7041-8HK85-1HA06ES7416-2XK04-0AB06GK7443-1EX20-0XE06SY7010-0AB286SY7010-0AB30METEOR2-MC/1C1756-A131756-A171756-ENBT1756-L611756-PA72IC695NKT0021756-BA11756-CP31756-IB161756-IB321756-IF81756-OB16E1756-OF41756-TBCH1756-TBNH2094-BM02-S2098-DSD-HV150-SE22B-D4P0N10406088201034MC160R2660D3G2A5-RT2013HAC16831-1XDM100USA4-11-28-URMEW01-1IC693CPU364CI810BDSAI130DSAO120DSDP170IC693BEM331IC693CMM321IC693CPU360IC693MDL655IC693MDL940DSBC176P0903CWA06B-0075-B103TS649SK401746-IB161746-IB81746-OB161746-OB81747-L5411747-SN193987GAN11-400-CNAEZ-S6C-F140DAI74000140DDO3530020-750-2262C-2R3HAC023195-001SSN-BG89ASM15/30-TC1747-L541C1756-A131756-DNB1756-IF161756-OF81756-OW16I1756-PA72140DDO35300140CPU671601398-DDM-030SGMG-20A2BBHD-CDIM00HD-CDOM001769-OF8C1746-OW164407B5061B5071C9020A1756-PB751769-ECR1769-IA161769-IQ161769-OB161769-SDN22B-D010N10422B-D2P3N10422-COMM-D440R-M23143440R-N23132MKD041B-144-GG1-KNFBM2043HAC025097-001/08DSQC639FBM204AB4A0088VB4A0002BBA0.75KW1756-CNB/EA06B-6130-H002A06B-6130-H003HD-CDIBS00SGMAV-04A3A61821GM-IS1SH2-M823DP-13SISM2-MJAMSC-B2110AVJAMSC-B2504VJAMSC-B2603VJAMSC-B2742VJRMSI-MB22AJRMSP-PS22AVFBM2041606-XL240EMLPS-10A606ES7131-0BL00-0XB06ES7132-0BL01-0XB02094BC04M03-S6DS1412-8RR6DS1717-8RRARS21056SE6430-2UD31-1CA0（要求带面板）TSX3722001MVI56-MCMSST-PFB-CLXLEM-AB-140N-21-NNNN1764-24BWA1764-LSP1769-IF4XOF21769-IF81769-IQ161769-OA16FBM20430084351B8312GOVERNOR-505PROTECH-203140ACI03000140ATI03000140CPU53414B140CRA93100140CRP93100140DDI35300140DDO35300140NOE771016DD1681-0AH21768-ENBT1768-L431768-PB32094-BC02-M02-S2094-BM02-S1771-ASB1771-IVN1771-OBN1771-OFE21771-P4S1771-P6S1771-P71785-BCM1785-L40B1785-L60BIC693CPU3743408IC200ALG321IC200ALG321IC200MDD844IC200MDL650IC200MDL750IC695CRU320IC695PSD140IC695RMX128PCI-7813RIC693CPU374FBM2046ES7153-1AA03-OXBO6ES7321-1BL00-OAA06E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