普通IO模拟i2c总线

1 #include <REGX51.H>
2
3 #define uchar unsigned char
4 #define uint unsigned int
5
6 void init();
7 void start();
8 void stop();
9 void write(uchar byte);
10 void write_add(uchar byte,uchar address);//向指定地址中写入字节
11 void delay1(uchar x);
12 uchar read_add(uchar address);
13 uchar read();//从指定地址中读出字节
14
15 void delay()
16 {;;}
17
18 sbit led = P0^0;
19 sbit sck = P2^0;
20 sbit sad = P2^1;
21
22 void main()
23 {
24     uchar test = 0;
25     init();
26     write_add(0x01,0xaf);
27     delay1(100);
28
29     test =read_add(0xaf);
30     if(test == 0x01)
31         led = 0;
32     while(1);
33 }
34
35 void init()
36 {
37     sck = 1;
38     delay();
39     sad = 1;//数据线和信号线都空闲
40     delay();
41     led = 1;
42 }
43 //起始信号
44 void start()
45 {
46     sad = 1;
47     delay();
48     sck = 1;
49     delay();
50     sad = 0;
51     delay();
52 }
53 //停止信号
54 void stop()
55 {
56     sad = 0;
57     delay();
58     sck = 1;
59     delay();
60     sad = 1;
61     delay();
62 }
63 //等待回应
64 void response()
65 {
66     uchar i = 0;
67     sck = 1;
68     delay();
69     while((sad == 1) && (i < 250))
70         i++;
71     sck = 0;
72     delay();
73 }
74 //向指定地址写入一个字节
75 void write(uchar byte)
76 {
77     uchar i = 0;
78     uchar temp = byte;
79
80     for(; i < 8; i++)
81     {
82         temp = temp << 1;//temp左移一位
83         sck = 0;
84         delay();
85         sad = CY;
86         delay();
87         sck = 1;
88         delay();
89     }
90     sck = 0;
91     delay();//这样就不会产生开始信号或结束信号
92     sad = 1;
93     delay();
94 }
95 //从指定地址读取一个字符
96 uchar read()
97 {
98     uchar i,k;
99     sck = 0;
100     delay();
101     sad = 1;
102     delay();
103     for(; i < 8; i++)
104     {
105         sck = 1;
106         delay();
107         k = (k << 1) | sad;
108         sck = 0;
109         delay();
110     }
111     return k;
112 }
113 //写入一个字节
114 void write_add(uchar byte,uchar address)
115 {
116     start();
117     write(0xa0);
118     response();
119     write(address);
120     response();
121     write(byte);
122     response();
123     stop();
124 }
125 //读出写入的字节
126 uchar read_add(uchar address)
127 {
128     uchar result;
129     start();
130     write(0xa0);
131     response();
132     write(address);
133     response();
134     start();
135     write(0xa1);
136     response();
137     result = read();
138     stop();
139     return result;
140 }
141 void delay1(uchar x)
142 {
143     uchar a,b;
144     for(a=x;a>0;a--)
145      for(b=100;b>0;b--);
146 }