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unsigned char at24c02_sda_io(void) //修改IO口方向
{ DDRD&=~(BIT(5)); PORTD|=(BIT(5)); if((PIND&0x20)==0x00){return 0;} else{return 1;} } void at24c02_init(void) //at24c02初始化,开始状态都为"空闲" { at24c02_sda_set; delayus(5); at24c02_scl_set; delayus(5); } void at24c02_start(void) //at2c02启动信号;SCL高电平下,SDA从高电平到低电平的跳变 { at24c02_sda_set; delayus(5); at24c02_scl_set; delayus(5); at24c02_sda_clr; delayus(5); } void at24c02_stop(void) //at24c02停止信号;SCL高电平下,SDA从低电平到高电平的跳变 { at24c02_sda_clr; delayus(5); at24c02_scl_set; delayus(5); at24c02_sda_set; delayus(5); } void at24c02_response(void) //at24c02应答响应信号;SCL高电平下,如果at24c02收到数据,则会SDA拉低 { unsigned int x=0; at24c02_scl_set; delayus(5); while((at24c02_sda_io())&&(x<1000))x++; //等待是否有应答,如果一段时间应答不成功,则默认为应答成功 at24c02_scl_clr; delayus(5); } unsigned char at24c02_read_byte(void) //从at24c02读出数据 { unsigned char x,y; at24c02_scl_clr; delayus(5); at24c02_sda_set; delayus(5); for(x=0;x<8;x++) { at24c02_scl_clr; delayus(5); y=(y<<1)|at24c02_sda_io(); delayus(5); at24c02_scl_set; delayus(5); } return y; } void at24c02_write_byte(unsigned char byte) //向at24c02写入数据 { unsigned char x,y; for(x=0;x<8;x++) { y=byte&0x80; at24c02_scl_clr; delayus(5); if(y==0){at24c02_sda_clr;} else{at24c02_sda_set;} delayus(5); at24c02_scl_set; delayus(5); byte=byte<<1; delayus(5); } at24c02_scl_clr; delayus(5); at24c02_sda_clr; delayus(5); } void at24c02_write_data(unsigned char add,unsigned char data) //给at24c02指定地址写入数据 { at24c02_start(); at24c02_write_byte(0xA0); //0xA0:写数据,0xA1:读数据; at24c02_response(); at24c02_write_byte(add); at24c02_response(); at24c02_write_byte(data); at24c02_response(); at24c02_stop(); delayms(10); } unsigned char at24c02_read_data(unsigned char add) //从A24C02指定地址中读出数据 {//0xA0:写数据,0xA1:读数据; unsigned char data; at24c02_start(); at24c02_write_byte(0xA0); at24c02_response(); at24c02_write_byte(add); at24c02_response(); at24c02_start(); at24c02_write_byte(0xA1); at24c02_response(); data=at24c02_read_byte(); at24c02_stop(); delayms(10); return data; } 为什么连续写入两次数据,才能存入数据,并且正确的读出数据?如果写入一次数据的话,读出的数据还是写入之前的数据(等于数据没有存进去)?? |
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