51系列單片機中英文翻譯資料(已改無錯字)
2022-12-16 05:34:06 本頁面
【正文】 uter have four 8 walk abreast I/O port, call P0, P1, P2 and P3. Each port is 8 accurate twoway mouths, accounts for 32 pins altogether. Every one I/O line can be used as introduction and exported independently. Each port includes a latch (namely special function register ), one exports the driver and a introduction buffer . Make data can latch when outputting, data can buffer when making introduction , but four function of passway these selfsame. Expand among the system of memory outside having slice, four port these may serve as accurate twoway mouth of I/O in mon use. Expand among the system of memory outside having slice, P2 mouth see high 8 address off。 P0 mouth is a twoway bus, send the introduction of 8 low addresses and data / export in timesharing The circuit of 8051 onechip puters and four I/O ports is very ingenious in design. Familiar with I/O port logical circuit, not only help to use ports correctly and rationally, and will inspire to designing the peripheral logical circuit of onechip puter to some extent. Load ability and interface of port have certain requirement, because output grade, P0 of mouth and P1 end output, P3 of mouth grade different at structure, so, the load ability and interface of its door demand to have nothing in mon with each other. P0 mouth is different from other mouths, its output grade draws the resistance supremly. When using it as the mouth in mon use to use, output grade is it leak circuit to turn on, is it is it urge NMOS draw the resistance on taking to be outer with it while inputting to go out to fail. When being used as introduction, should write 1 to a latch first. Every one with P0 mouth can drive 8 Model LS TTL load to export. P1 mouth is an accurate twoway mouth too, used as I/O in mon use. Different from P0 mouth output of circuit its, draw load resistance link with power on inside have. In fact, the resistance is that two effects are in charge of FET and together: One FET is in charge of load, its resistance is regular. Another one can is it lead to work with close at two state, make its President resistance value change approximate 0 or group value heavy two situation very. When it is 0 that the resistance is approximate , can draw the pin to the high level fast 。 When resistance value is very large, P1 mouth, in order to hinder the introduction state high. Output as P1 mouth high electricity at ordinary times, can is it draw electric current load to offer outwards, draw the resistance on needn39。t answer and thenning. Here when the port is used as introduction, must write into 1 to the corresponding latch first too, make FET end. Relatively about 20,000 ohms because of the load resistance in scene and because 40,000 ohms, will not exert an influence on the data that are input. The structure of P2 some mouth is similar to P0 mouth, there are MUX switches. Is it similar to mouth partly to urge, but mouth large a conversion controls some than P1. P3 mouth one multifunctional port, mouth getting many than P1 it have and 3 door and 4 buffer. Two part these, make her besides accurate twoway function with P1 mouth just, can also use the second function of every pin, and door 3 function one switch in fact, it determines to be to output data of latch to output second signal of function. Act as W =At 1 o39。clock, output Q end signal。 Act as Q =At 1 o39。clock, can output W line signal . At the time of programming, it is
公司管理相關(guān)推薦
鄂ICP備17016276號-1