51 single chip microcomputer----sbit

Typical application: sbit P0_0=P0^0; // defines P0_0 as the first bit of port P0 for bit operation.

Usage:​

In C language, if you write P1.0 directly, the C compiler cannot recognize it, and P1.0 is not a legal C language variable name, so you have to give it another name, here it is called P1_0, but is P1_0 the same as P1.0? You think so, but the C compiler doesn't think so, so you have to establish a connection between them. Here, the Keil C keyword sbit is used to define it. There are three uses of sbit:

The first method: sbit bit variable name = address value

The second method: sbit bit variable name = SFR name ^ variable bit address value

The third method: sbit bit variable name = SFR address value ^ variable bit address value

The following three methods can be used to define OV in PSW:

sbit OV=0xd2 (1) Description: 0xd2 is the bit address value of OV

sbit OV=PSW^2 (2) Note: PSW must be defined first using sfr

sbit OV=0xD0^2 (3) Note: 0xD0 is the address value of PSW

Therefore, here we use sbit P1_0=P1^0; to define the symbol P1_0 to represent the P1.0 pin. If you want, you can also use a name like P10, as long as you change it accordingly in the following program.

sbit and bit:

​sbit must be defined at the outermost, that is, it must be defined as an external variable. sbit defines the bit of SFR (special function register)

sbit is more like a type definition than a variable definition.

sbit: just an illustrative note

A bit can be defined externally or internally.

Reference link: http://baike.baidu.com/link?url=R_fzVbhmSpnJIcMdnyH1kJFNiJRW2wMLb-zjl9gr-Ht779OltInqwjJpibGxATyR7pLLTOMI4EQLNLaOCKZ1iK​