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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