51系列單片機(jī)中英文翻譯資料-閱讀頁
2024-11-23 05:34本頁面
【正文】 : 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 。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。 Act as Q =At 1 o39。t have software that set up P3 mouth in advance . It hardware not inside is the automatic to have two function outputted when CPU carries on SFR and seeks the location (the location or the byte ) to visit to P3 mouth /at not lasting lining, there are inside hardware latch Qs = operation principle of P3 mouth is similar to P1 mouth. Output grade , P3 of mouth , P1 of P1 , connect with inside have load resistance of drawing , every one of they can drive 4 Model LS TTL load to output. As while inputting the mouth, any TTL or NMOS circuit can drive P1 of 8051 onechip puters as P3 mouth in a normal way . Because draw resistance on output grade of them have, can open a way collector too or drainsource resistance is it urge to open a way, do not need to have the resistance of drawing outerly . Mouths are all accurate twoway mouths too. When the conduct is input, must write the corresponding port latch with 1 first . As to 80C51 onechip puter, port can only offer milliampere of output electric currents, is it output mouth go when urging one ordinary basing of transistor to regard as, should contact a resistance among the port and transistor base , in order to the electricity while restraining the high level from exporting P1~P3 Being restored to the throne is the operation of initializing of an onechip puter. Its main function is to turn PC into 0000H initially , make the onechip puter begin to hold the conduct procedure from unit 0000H. Except that the ones that enter the system are initialized normally,as because procedure operate it make mistakes or operate there aren39。s trigger, restore to the throne circuit sample to output , Schmitt of trigger constantly in each S5P2 , machine of cycle in having one more , then just got and restored to the throne and operated the necessary signal insidly. Restore to the throne resistance of circuit generally, electric capacity parameter suitable for 6 brilliant to shake, can is it restore to the throne signal high level duration greater than 2 machine cycles to guarantee. Being restored to the throne in the circuit is simple, its function is very important. Pieces of onechip puter system could normal running,should first check it can restore to the throne not succeeding. Checking and can pop one39
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