51单片机SPI协议与应用实例

  1 #include <reg52.h>
  2 typedef unsigned char uchar;
  3 typedef unsigned int uint;
  4 //写操作控制字节,D7=1,D0=0
  5 uchar code write_address[] =
  6 {
  7     //秒,分,小时,日,月,星期,年
  8     0x80, 0x82, 0x84, 0x86, 0x88, 0x8a, 0x8c
  9 };
 10 //读操作,D7=1,D0=1,地址同写操作
 11 uchar code read_address[] =
 12 {
 13     0x81, 0x83, 0x85, 0x87, 0x89, 0x8b, 0x8d
 14 };
 15 uchar code table[] =
 16 {
 17     //0,1,2,3,4,5,6,7,8,9
 18     0xfc, 0x60, 0xda, 0xf2, 0x66, 0xb6, 0xbe, 0xe0, 0xfe, 0xf6
 19 };
 20 //dat1和dat2存放读出来的时间,初始值写入12年5月9日1时1分1秒,dat1存放1234位,dat2存放567位
 21 uchar dat1[] = {0x01, 0x01, 0x01, 0x09, 0x05, 0x02, 0x12};
 22 uchar dat2[] = {0x01, 0x01, 0x01, 0x09, 0x05, 0x02, 0x12};
 23 sbit rst = P3 ^ 0;
 24 sbit scl = P3 ^ 1;
 25 sbit sda = P3 ^ 2;
 26 sbit ACC7 = ACC ^ 7;
 27 void Delay(uint m)
 28 {
 29     while(m--);
 30 }
 31 /* SPI协议操作,读字节 */
 32 uchar ReadByte()
 33 {
 34     uchar i;
 35     for (i = 0; i < 8; ++i)
 36     {
 37         ACC = ACC >> 1; //累加器左移1位,补上未知数x
 38         ACC7 = sda; //从sda引脚写入ACC最高位
 39         scl = 1;
 40         scl = 0; //时钟下降沿读入
 41     }
 42     return ACC;
 43 }
 44 /* SPI协议操作,写字节 */
 45 void WriteByte(uchar byte)
 46 {
 47     uchar i;
 48     for (i = 0; i < 8; ++i)
 49     {
 50         byte >>= 1; //byte左移1位存入CY
 51         scl = 0;
 52         sda = CY; //从CY移入sda,发送给DS102
 53         scl = 1; //时钟上升沿写入
 54     }
 55 }
 56 void Write1302(uchar address, uchar dat) //写地址子程序
 57 {
 58     rst = 0;
 59     scl = 0;
 60     rst = 1; //rst上升沿开始写数据
 61     WriteByte(address); //先写入地址控制字节
 62     WriteByte(dat); //再写入数据字节
 63     rst = 0;
 64 }
 65 uchar Read1302(uchar address)
 66 {
 67     uchar temp;
 68     rst = 0;
 69     scl = 0;
 70     rst = 1; //读过程中保持rst高电平状态
 71     WriteByte(address | 0x01); //写入地址并置R/W位为1(读)
 72     temp = ReadByte(); //在单片机写入命令字节的最后一位的第一个下降沿处即读出数据
 73     scl = 1; 
 74     rst = 0;
 75     return temp;
 76 }
 77 void SetRST()
 78 {
 79     uchar i;
 80     Write1302(0x8e, 0x00); //向10001110写保护寄存器,写入指令0x00
 81     for (i = 0; i < 7; ++i)
 82         Write1302(write_address[i], dat1[i]); //从秒到年各寄存器写入对应初始值
 83     Write1302(0x8e, 0x80); //向写保护寄存器,写入数据0x80
 84 }
 85 void ReadTime()
 86 {
 87     uchar i, temp1, temp2, temp3;
 88     temp3 = 0x80; //temp3存放时间寄存器地址
 89     for (i = 0; i < 7; ++i) //分别读出秒分小时日月星期年
 90     {
 91         temp1 = Read1302(temp3);
 92         temp2 = temp1;
 93         dat1[i] = (temp1 >> 1) & 0x0f; //读出的数据1234位存入dat1,屏蔽其他位
 94         dat2[i] = (temp2 >> 5) & 0x07; //读出的数据567位存入dat2,屏蔽其他位
 95         temp3 = temp3 + 0x02; //下一个寄存器地址
 96     }
 97 }
 98 void main()
 99 {
100     rst = 0;
101     SetRST(); //时钟建立
102     while(1)
103     {
104         ReadTime(); //读时间
105         P2 = 0xfe;
106         P1 = table[dat1[0] % 10];
107         Delay(500);
108         P2 = 0xfd;
109         P1 = table[dat2[0] % 10];
110         Delay(500);
111         P2 = 0xfb;
112         P1 = 0x02; // -
113         Delay(500);
114         P2 = 0xf7;
115         P1 = table[dat1[1] % 10];
116         Delay(500);
117         P2 = 0xef;
118         P1 = table[dat2[1] % 10];
119         Delay(500);
120         P2 = 0xdf;
121         P1 = 0x02; // -
122         Delay(500);
123         P2 = 0xbf;
124         P1 = table[dat1[2] % 10];
125         Delay(500);
126         P2 = 0x7f;
127         P1 = table[dat2[2] % 10];
128         Delay(500);
129     }
130 }