89C51 is externally connected with two 6264 and one 8255, which can be connected with Y0 and y18255 of 74LS138 and P2 of 89C51 respectively 0?

CSDN Q & A 2022-05-15 04:45:42 阅读数:658


As the title , There are still several problems
①CE and CS What's the difference between the two pins ?
② Is it up to you to decide which pins to connect to the external chip ?

Take the answer :

According to the standard bus connection method , Of course 138 Another decoded signal , In this way, you can directly access , use P2 Words , It's troublesome to operate , Add one more instruction .
① Almost
② It depends on the pin function of the chip , System functional requirements , There are also some distribution principles in practical use ( For example, address division )

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