I2C communication

[deexith hasan]

I can able to understand transmitting data through I2C..but in receiving data its tough
for me..

in this website i can see 2 SCL and SDA

https://www.robot-electronics.co.uk/acat.../I2C_Tutorial.html

unsigned char i2c_rx(char ack)
   {
   char x, d=0;
   SDA = 1;
   for(x=0; x<8; x++) {
      d <<= 1;
      do {  
         SCL = 1;
      }
      while(SCL_IN==0); // wait for any SCL clock stretching
      i2c_dly();
      if(SDA_IN) d |= 1;
      SCL = 0;
   }
   if(ack) SDA = 0;
   else SDA = 1;
   SCL = 1;
   i2c_dly(); // send (N)ACK bit
   SCL = 0;
   SDA = 1;
   return d;
}

in this program where i cant find any digitalread.....

 

[Ian Rogers]

I placed your code in "Code" tags to make it easier to read...

If(SDA_IN) d |= 1; .... This line reads the I2C bus..

d <<= 1; ... This line shifts the receive buffer..

This happens for 8 iterations....

 

[deexith hasan]

thanq its now clear that there is read line in I2C rx....but in I2C only 2 pins are needed (SDA,SCL) then what about SDA_IN and SCL_IN pin??

 

[Ian Rogers]

Its the same pin.... They are just named so you can read it clearer.. It you look at my tutorials ( I think its Tutorial 6 ) I have made software I2C routines... I have clearly remarked on the operation.. The link is in my signature..