140 lines
2.3 KiB
C
140 lines
2.3 KiB
C
/* # I2C代码片段说明
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1. 本文件夹中提供的驱动代码供参赛选手完成程序设计参考。
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2. 参赛选手可以自行编写相关代码或以该代码为基础，根据所选单片机类型、运行速度和试题
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中对单片机时钟频率的要求，进行代码调试和修改。
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*/
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#include "iic.h"
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#include "intrins.h"
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#define DELAY_TIME 5
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sbit scl = P2 ^ 0;
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sbit sda = P2 ^ 1;
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//
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static void I2C_Delay(unsigned char n)
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{
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do
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{
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_nop_();
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_nop_();
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_nop_();
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_nop_();
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_nop_();
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_nop_();
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_nop_();
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_nop_();
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_nop_();
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_nop_();
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_nop_();
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_nop_();
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_nop_();
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_nop_();
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_nop_();
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} while (n--);
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}
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//
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void I2CStart(void)
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{
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sda = 1;
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scl = 1;
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I2C_Delay(DELAY_TIME);
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sda = 0;
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I2C_Delay(DELAY_TIME);
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scl = 0;
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}
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//
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void I2CStop(void)
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{
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sda = 0;
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scl = 1;
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I2C_Delay(DELAY_TIME);
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sda = 1;
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I2C_Delay(DELAY_TIME);
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}
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//
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void I2CSendByte(unsigned char byt)
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{
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unsigned char i;
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for (i = 0; i < 8; i++)
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{
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scl = 0;
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I2C_Delay(DELAY_TIME);
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if (byt & 0x80)
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{
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sda = 1;
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}
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else
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{
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sda = 0;
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}
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I2C_Delay(DELAY_TIME);
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scl = 1;
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byt <<= 1;
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I2C_Delay(DELAY_TIME);
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}
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scl = 0;
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}
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//
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unsigned char I2CReceiveByte(void)
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{
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unsigned char da;
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unsigned char i;
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for (i = 0; i < 8; i++)
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{
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scl = 1;
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I2C_Delay(DELAY_TIME);
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da <<= 1;
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if (sda)
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da |= 0x01;
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scl = 0;
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I2C_Delay(DELAY_TIME);
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}
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return da;
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}
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//
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unsigned char I2CWaitAck(void)
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{
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unsigned char ackbit;
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scl = 1;
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I2C_Delay(DELAY_TIME);
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ackbit = sda;
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scl = 0;
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I2C_Delay(DELAY_TIME);
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return ackbit;
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}
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//
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void I2CSendAck(unsigned char ackbit)
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{
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scl = 0;
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sda = ackbit;
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I2C_Delay(DELAY_TIME);
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scl = 1;
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I2C_Delay(DELAY_TIME);
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scl = 0;
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sda = 1;
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I2C_Delay(DELAY_TIME);
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}
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// 写入的值是数字值0-255，而不是模拟值
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void Da_Write(unsigned char dat)
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{
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// 选择芯片为PCF
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I2CStart();
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I2CSendByte(0x90);
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I2CWaitAck();
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I2CSendByte(0x41);
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I2CWaitAck();
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I2CSendByte(dat);
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I2CWaitAck();
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I2CStop();
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}
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