十天学会单片机Day6 学会看数据手册 (IIC总线PCF859芯片( A/D D/A)应用)

Posted 2020-07-07 kuotian

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