Hello, referencing I2C_out() and I2C_in() from Don Bindner's code. I created the function below called pH_info. Notice my last I2C_in() byte read I use an argument of "0" to receive the ACK. If you need an ACK you need to pull down the data line first. Disclaimer: It has been awhile since I used this code, but I remember it working great.

/* Outputs 8-bit command or data via I2C lines. */ void I2C_out(unsigned char d) { int n;

 for( n = 0; n < 8; n++ ) {
     if( d & 0x80 ) {
         data_high();
     } else {
         data_low();
     }

     clk_high();
     clk_low();

     d <<= 1;        // Shift next bit into position.
 }

 data_read();        // Set data line to receive.
 clk_high();         // Clock goes high to wait for acknowledge.

 // Slave will pull data line low to acknowledge.
 while( P1IN & I2C_SDA ) {
     // Else toggle the clock line and check again
     clk_low();
     clk_high();
 }

 clk_low();

}

/* Inputs 8-bit data from slave, with or without acknowledgement. */ unsigned char I2C_in(int ack) { int n; unsigned char byte = 0;

 data_read();                // Float line to read bits.
 for( n = 0; n < 8; n++ ) {
     byte <<= 1;             // Shift bits over to make room for new bit.

     clk_high();

     if( data_pulled_up()) {
         byte |= 1;          // Slave sent a 1.
     }

     clk_low();
 }

 /* If we need to acknowledge, we'll pull down the data line. */
 if( ack ) {
     data_low();
 }

 clk_high();
 clk_low();

 return byte;

}

/This function sends a request for info to the I2C pH circuit and reads back the information data/ void pH_info(void) { I2C_Start(); I2C_out(0xC6); //Write address of I2C slave I2C_out(0x49); //ASCII 'L' I2C_Stop();

  delay(1000);

  I2C_Start();
  I2C_out(0xC7); //Read address of I2C slave
  rxdata[0]=I2C_in(1);
  rxdata[1]=I2C_in(1);
  rxdata[2]=I2C_in(1);
  rxdata[3]=I2C_in(1);
  rxdata[4]=I2C_in(1);
  rxdata[5]=I2C_in(1);
  rxdata[6]=I2C_in(1);
  rxdata[7]=I2C_in(1);
  rxdata[8]=I2C_in(1);
  rxdata[9]=I2C_in(1);
  rxdata[10]=I2C_in(0);

}