Microcontroller I2C driver-EEWORLD

Collect

void delay()

{; ;}

void delay1ms ( uint z )
{
uint x, y;
for ( x = z; x >
0; x -- ) for ( y = 110; y > 0; y -- );
}

I2C startup: falling edge on SDA while SCL is high

void start_I2C ( ) /
{
sda = 1;
delay ();
scl = 1;
delay ();
sda = 0;
delay ();
}

I2C stop: A rising edge occurs on SDA during SCL high level

void stop_I2C () //Stop
{
sda = 0;
delay ();
scl = 1;
delay ();
sda = 1;
delay ();
}

Bus initialization: pull the bus high to release the bus

void init_I2C ()
{
sda = 1;
delay ();
scl = 1;
delay ();
}

Answer signal: During the high level of SCL, SDA is pulled low by the slave device to indicate the answer.

void response ()//Response
{
uchar i;
scl = 1;
delay ();
while ( ( sda == 1 ) && ( i < 250 ) ) i ++; // i < 255 here only means that there is no response, If i > 255, exit directly to avoid an infinite loop.
scl = 0;
delay ();
}

Write a byte: the high or low level on SDA can only change during the low period of SCL

void write_byte (uchar date)
{
uchar i, temp;
temp = date;
for ( i = 0; i < 8; i ++ )
{
temp = temp << 1; //Move the highest bit into CY
scl = 0;
delay ();
sda = CY;
delay ();
scl = 1;
delay ();
}

scl = 0;
delay ();
sda = 1;
delay ();

}

Read a byte:

uchar read_byte ()
{
uchar i, k;
scl = 0;
delay ();
sda = 1;
delay ();
for ( i = 0; i < 8; i ++ )
{
scl = 1;
delay ();
k = ( k << 1 ) | sda; // Also read from the highest bit
scl = 0;
delay ();
}
return k;

}

Reference address：Microcontroller I2C driver

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