A)应用)

1.实际电路

2.引脚图

3.地址

高四位为固定地址1001，A2A1A0可编程地址，通过观察实际电路，可知A2A1A0 为000。最低位为读写为，1为读，0为写。

4.控制字

控制寄存器的高半字节用于允许模拟输出将模拟输入编程为单端或差分输入

低半字节选择一个由高半字节定义的模拟输入通道。如果自动增量标志(AUTO-INCREMENT FLAG)置1，每次A/D转换后通道号将自动增加。

5.开始停止信号

 1 void Start()
 2 {
 3     SDA = 1;
 4     delay();
 5     SCL = 1;
 6     delay();  
 7     SDA = 0;
 8     delay();    
 9 }
10 
11 void Stop()
12 {
13     SDA = 0;
14     delay();
15     SCL = 1;
16     delay();
17     SDA = 1;
18     delay();
19 }

View Code

6.应答非应答信号

 1 void Respons()
 2 {
 3     SDA = 0;
 4     delay();
 5     SCL = 1;
 6     delay();
 7     SCL = 0;
 8     delay();
 9 }
10 
11 void NoRespons()
12 {
13     SDA = 1;
14     delay();
15     SCL = 1;
16     delay();
17     SCL = 0;
18     delay();
19 }

View Code

7.位传输

 1 void write_byte(unsigned char dat)
 2 {
 3     unsigned char i = 0;
 4     for(i = 0; i < 8; i++) {
 5         dat = dat<<1;
 6         SCL = 0;
 7         delay();
 8         SDA = CY;    //类似于8086的PSW的CF位 即左移data溢出位进入CY
 9         delay();
10         SCL = 1;
11         delay();    
12     }
13     SCL = 0;
14     delay();
15     SDA = 1;
16     delay();
17 }
18 
19 unsigned char read_byte()
20 {
21     unsigned char i = 0, dat;
22     SCL = 0;
23     delay();
24     SDA = 1;
25     for(i = 0; i < 8; i++) {
26         SCL = 1;
27         delay();
28         dat = (dat<<1) | SDA;
29         SCL = 0;
30         delay();
31     }
32     return dat;
33 }

View Code

8.IIC总线协议 A/D

读模式总线协议

 1 unsigned char readAdc()
 2 {
 3     unsigned char dat;
 4     Start();
 5     write_byte(0x90);      //前四位地址1001 后三位根据硬件000 最后一位R/W(上划线) 写信号
 6     Respons();
 7     write_byte(0x40);        //控制字 通道0
 8     Respons();
 9     
10     Start();
11     write_byte(0x91);      //前四位地址1001 后三位根据硬件000 最后一位R/W(上划线) 读信号
12     Respons();
13     dat =  read_byte();
14     NoRespons();
15     Stop();
16     return dat;
17 }

9.IIC总线协议 D/A

写模式总线协议

void writeDAC(unsigned char dat)
{
    Start();
    write_byte(0x90);      //前四位地址1001 后三位根据硬件000 最后一位R/W(上划线) 写信号
    Respons();
    write_byte(0x40);       //控制字
    Respons();
    write_byte(dat); 
    Respons();
    Stop();
}

10.功能实现

  1 //IIC PCF8591 A/D D/A
  2 #include <reg52.h>
  3 #include <stdio.h>
  4 #define uchar unsigned char
  5 sbit SDA = P2^0;
  6 sbit SCL = P2^1;
  7 
  8 void delay()
  9 {;;}
 10 
 11 void delayms(unsigned int n)   //误差 -0.651041666667us
 12 {
 13     unsigned char a,b;
 14     unsigned int i;
 15     for(i = 0; i < n; i++) {
 16         for(b=4;b>0;b--)
 17             for(a=113;a>0;a--);
 18     }
 19 }
 20 
 21 void InitUART(void)
 22 {
 23     TMOD = 0x20;
 24     SCON = 0x50;
 25     TH1 = 0xFD;
 26     TL1 = TH1;
 27     PCON = 0x00;
 28     TR1 = 1;
 29 }
 30 
 31 
 32 void Init()
 33 {
 34     SCL = 1;
 35     delay(); 
 36     SDA = 1;
 37     delay();     
 38 }
 39 
 40 void Start()
 41 {
 42     SDA = 1;
 43     delay();
 44     SCL = 1;
 45     delay();  
 46     SDA = 0;
 47     delay();    
 48 }
 49 
 50 void Stop()
 51 {
 52     SDA = 0;
 53     delay();
 54     SCL = 1;
 55     delay();
 56     SDA = 1;
 57     delay();
 58 }
 59 
 60 void Respons()
 61 {
 62     SDA = 0;
 63     delay();
 64     SCL = 1;
 65     delay();
 66     SCL = 0;
 67     delay();
 68 }
 69 
 70 void NoRespons()
 71 {
 72     SDA = 1;
 73     delay();
 74     SCL = 1;
 75     delay();
 76     SCL = 0;
 77     delay();
 78 }
 79 
 80 void write_byte(unsigned char dat)
 81 {
 82     unsigned char i = 0;
 83     for(i = 0; i < 8; i++) {
 84         dat = dat<<1;
 85         SCL = 0;
 86         delay();
 87         SDA = CY;    //类似于8086的PSW的CF位 即左移data溢出位进入CY
 88         delay();
 89         SCL = 1;
 90         delay();    
 91     }
 92     SCL = 0;
 93     delay();
 94     SDA = 1;
 95     delay();
 96 }
 97 
 98 unsigned char read_byte()
 99 {
100     unsigned char i = 0, dat;
101     SCL = 0;
102     delay();
103     SDA = 1;
104     for(i = 0; i < 8; i++) {
105         SCL = 1;
106         delay();
107         dat = (dat<<1) | SDA;
108         SCL = 0;
109         delay();
110     }
111     return dat;
112 }
113 
114 
115 unsigned char readAdc()
116 {
117     unsigned char dat;
118     Start();
119     write_byte(0x90);      //前四位地址1001 后三位根据硬件000 最后一位R/W(上划线) 写信号
120     Respons();
121     write_byte(0x40);        //控制字 通道0
122     Respons();
123     
124     Start();
125     write_byte(0x91);      //前四位地址1001 后三位根据硬件000 最后一位R/W(上划线) 读信号
126     Respons();
127     dat =  read_byte();
128     NoRespons();
129     Stop();
130     return dat;
131 }
132 
133 
134 void writeDAC(unsigned char dat)
135 {
136     Start();
137     write_byte(0x90);      //前四位地址1001 后三位根据硬件000 最后一位R/W(上划线) 写信号
138     Respons();
139     write_byte(0x40);       //控制字
140     Respons();
141     write_byte(dat); 
142     Respons();
143     Stop();
144 }
145 
146 void SendOneByte(unsigned char c)
147 {
148     SBUF = c;
149     while(!TI);
150     TI = 0;
151 }
152 int main()
153 {
154     unsigned char dat;
155     unsigned char tmpDA = 0;
156     Init();
157     InitUART();
158     
159     while(1)
160     {     
161         delayms(200);
162         dat = readAdc();    
163         SendOneByte(dat);
164 
165         tmpDA++;
166         if(tmpDA == 255)
167             tmpDA = 0;
168         writeDAC(tmpDA);
169     }
170     return 0;
171 }

AD直接采集DA出来的电压串口发送验证成功

posted on 2016-05-17 17:54 kuotian 阅读(1855) 评论(0) 编辑收藏举报