这是读写的时序
//产生IIC起始信号
void IIC_Start(void)
{
SDA_OUT(); //sda线输出
SDA_HIGH;
SCL_HIGH;
delay_us(4);
SDA_LOW; //START:when CLK is high,DATA change form high to low
delay_us(4);
SCL_LOW; //钳住I2C总线，准备发送或接收数据
}
//产生IIC停止信号
void IIC_Stop(void)
{
SDA_OUT(); //sda线输出
SDA_LOW; //STOP:when CLK is high DATA change form low to high
delay_us(4);
SCL_HIGH;
delay_us(4);
SDA_HIGH; //发送I2C总线结束信号
delay_us(4);
}
// 等待应答信号到来
// 返回值：1，接收应答失败
// 0，接收应答成功
u8 IIC_Wait_Ack(void)
{
u8 ucErrTime=0;
SDA_IN(); //SDA设置为输入
SDA_HIGH;delay_us(1); //似乎有问题
SCL_HIGH;delay_us(1); //似乎有问题
while(READ_SDA)
{
ucErrTime++;
if(ucErrTime>250)
{
//IIC_Stop();
return 1;
}
}
SCL_LOW; //时钟输出0
ack++; //调试用看应答了几次
return 0;
}
//主机产生ACK应答
void IIC_Ack(void)
{
SDA_OUT();
SCL_LOW; //时钟输出0
SDA_LOW;
delay_us(2);
SCL_HIGH;
delay_us(2);
SCL_LOW;//时钟输出0
}
//IIC发送一个字节
//返回从机有无应答
//1，有应答
//0，无应答
void IIC_Send_Byte(u8 txd)
{
u8 t;
SDA_OUT();
SCL_LOW;
for(t=0;t<8;t++)
{
if(txd&0x80)SDA_HIGH;
else SDA_LOW;
txd<<=1;
delay_us(2);
SCL_HIGH;
delay_us(2);
SCL_LOW;
delay_us(2);
}
}
//读1个字节，ack=1时，发送ACK，ack=0，发送nACK
u8 IIC_Read_Byte(void)
{
unsigned char i,receive=0;
SDA_IN();//SDA设置为输入
for(i=0;i<8;i++ )
{
SCL_LOW;
delay_us(2);
SCL_HIGH;
delay_us(2);
receive<<=1;
if(READ_SDA)receive++;
delay_us(1);
}
IIC_Wait_Ack();
return receive;
}
//初始化
void ADS1115_Init()
{
IIC_Start();
IIC_Send_Byte(0x90);
IIC_Wait_Ack();
IIC_Send_Byte(0x01);
IIC_Wait_Ack();
IIC_Send_Byte(0x82);
IIC_Wait_Ack();
IIC_Send_Byte(0xe3);
IIC_Wait_Ack();
IIC_Stop();
}
//读取数据
u16 I2C_Read()
{
u16 temp;
IIC_Start();
IIC_Send_Byte(0x90);
IIC_Wait_Ack();
IIC_Send_Byte(0x00);
IIC_Wait_Ack();
//IIC_Stop();
IIC_Start();
IIC_Send_Byte(0x91);
IIC_Wait_Ack();
AD_BUF[0]=IIC_Read_Byte();
AD_BUF[1]=IIC_Read_Byte();
IIC_Wait_Ack();
IIC_Stop();
temp=(AD_BUF[0] << 8) | AD_BUF[1];
return temp;
}
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