I2C接口的输入与输出驱动的.docx

1、I2C接口的输入与输出驱动的I2C接口的输入与输出驱动的PCF8574-pcf8574采用I2C接口，有8个准双向口，可以和外部电路连接，来实现输入输出功能，可以用来对口线进行扩展有几点需要注意1.某位作为输入的时候，必须首先置为高电平2.地址是0100A2A1A0R/W3.最多可以扩展8片4.低电流损耗，静态电流10uA,驱动电流比较大，而且有索存功能，能够驱动LED发光管5.带有外部中断输出，低电平有效我作了一个电路，其中P7-P4作为输入检测开关状态，P3-P0作为输出来驱动LED灯程序如下#include#defineSETBIT(VAR,Place)(VAR|=(1Place)#de

2、fineCLRBIT(VAR,Place)(VAR&=(1Place)255)sbitIC_SCL=P36;sbitIC_SDA=P37;unsignedcharIC_Re_Time;unsignedcharIC_Err_Flag;voidTimer0_Init(void)TMOD=0x00;信方式:I2C2.通信端口:IC_SCL,IC_SDA3.通信地址:0x0101000x？*/？voidIC_Start(void)/启动IC通信？IC_SDA=1;Delay();IC_SCL=1;Delay();IC_SDA=0;Delay();IC_SCL=0;Delay();？voidIC_Sto

3、p(void)/停止IC通信？IC_SDA=0;Delay();IC_SCL=1;Delay();IC_SDA=1;Delay();？voidIC_Receive_Ack(void)/接受ACK？IC_SDA=1;IC_SCL=1;？Delay();？IC_Re_Time=0;？while(IC_Re_Time=30)if(IC_SDA=0)IC_Err_Flag=0;break;？elseIC_Err_Flag=1;IC_SCL=0;Delay();/voidIC_Send_ACK(void)/发送ACK/ifreadmanydatasatatime,thiscanbeused/IC_SDA

4、=0;/Delay();/IC_SCL=1;/Delay();/IC_SCL=0;/Delay();/IC_SDA=1;/voidIC_Send_NAck(void)/发送NACKIC_SDA=1;Delay();IC_SCL=1;Delay();IC_SCL=0;Delay();voidIC_Write_Byte(unsignedcharData)/写数据到8574unsignedchari;？for(i=0;i=7;i+)if(VALBIT(Data,(7-i)/dataoutmsbIC_SDA=1;elseIC_SDA=0;IC_SCL=1;Delay();IC_SCL=0;Delay(

5、);？unsignedcharIC_Read_Byte(void)/从8574读取一个数据unsignedchari;unsignedcharData;for(i=0;i=7;i+)IC_SCL=1;Delay();IC_SDA=1;Delay();？if(IC_SDA)SETBIT(Data,(7-i);/datainmsbtooelseCLRBIT(Data,(7-i);IC_SCL=0;Delay();return(Data);voidIC_Write_Data(unsignedcharData)unsignedcharwrite_time;unsignedcharwrite_data;

6、write_data=Data;for(write_time=0;write_time=2;write_time+)？IC_Start();IC_Write_Byte(0x40);IC_Receive_Ack();IC_Write_Byte(write_data);IC_Receive_Ack();？IC_Stop();if(IC_Err_Flag=0)break;？unsignedcharIC_Read_Data(void)unsignedcharReturn_Data;unsignedcharread_time;for(read_time=0;read_time=2;read_time+)

7、？IC_Start();IC_Write_Byte(0x41);？IC_Receive_Ack();？Return_Data=IC_Read_Byte();？IC_Send_NAck();IC_Stop();？if(IC_Err_Flag=0)return(Return_Data);break;？voidPCF8574_Init(void)IC_Write_Data(0xf0);/输入状态的必须开始的时候置为1，输出为0voidmain(void)unsignedchartemp3;Timer0_Init();PCF8574_Init();while(1)temp3=IC_Read_Data(

8、);IC_Write_Data(0x0f);Delay();；中间可以添加你需要的模块，比如显示或者其他的操作等/*中断服务子程序*/externvoidexternal0_rt(void)interrupt0/INT0externvoideit0_rt(void)interrupt1/T0，标准，定时中断TH0=0x1e;TL0=0x0c;IC_Re_Time+;？voidexternal1_rt(void)interrupt2using1/INT1voideit1_rt(void)interrupt3using1/T1，标准voidsci_rt(void)interrupt4using1/UARTvoideit2_rt(void)interrupt5using1/T23种工作模式，输入捕捉、自动重载和波形发生器voidPCA_rt(void)interrupt6using1/PCAvoidKBDIT_rt(void)interrupt7using1/keyboardvoidspi_rt(void)interrupt9using1/SPI