[Solved] I2C-like communication

Using Arduino Programming Questions
13

I've tried different I2C master devices (Arduino, Aardvark) and they didn't work. I used a blog post used by the softwareI2Clib pylon pointed me to (Coding Laboratory: I2C on an AVR using bit banging) to create my own bit-banging application. For those interested, here is it:

// Port for the I2C
#define I2C_DDR DDRD
#define I2C_PIN PIND
#define I2C_PORT PORTD

// Pins to be used in the bit banging
#define I2C_CLK 0
#define I2C_DAT 1

#define I2C_DATA_HI() \
        I2C_DDR &= ~( 1 << I2C_DAT );\
        I2C_PORT |= ( 1 << I2C_DAT );
#define I2C_DATA_LO() \
        I2C_DDR |= ( 1 << I2C_DAT );\
        I2C_PORT  &=~ ( 1 << I2C_DAT );

#define I2C_CLOCK_HI() \
        I2C_DDR &= ~( 1 << I2C_CLK );\
        I2C_PORT |= ( 1 << I2C_CLK );
#define I2C_CLOCK_LO() \
        I2C_DDR |= ( 1 << I2C_CLK );\
        I2C_PORT  &=~ ( 1 << I2C_CLK );

int i = 0;
int g = 0;

void setup()
{
  I2C_Init();
  Serial.begin(9600);
}

void loop()
{
  
  while(i == 0)
  {
  I2C_Start();
  I2C_Write(0x01);
  g = I2C_Read(1);
  I2C_Read(1);
  I2C_Read(1);
  I2C_Read(1);
  I2C_Read(0);
  I2C_Stop();
  i++;
  }
  Serial.print(g);
  delay(500);
  
}

void I2C_WriteBit( unsigned char c )
{
if ( c > 0 )
{
I2C_DATA_HI();
}
else
{
I2C_DATA_LO();
}

I2C_CLOCK_HI();
delay(1);

I2C_CLOCK_LO();
delay(1);

if ( c > 0 )
{
I2C_DATA_LO();
}

delay(1);

}

unsigned char I2C_ReadBit()
{
I2C_DATA_HI();

I2C_CLOCK_HI();
delay(1);

unsigned char c = I2C_PIN;

I2C_CLOCK_LO();
delay(1);

return ( c >> I2C_DAT ) & 1;
}

// Inits bitbanging port, must be called before using the functions below
//
void I2C_Init()
{
I2C_PORT &= ~( ( 1 << I2C_DAT ) | ( 1 << I2C_CLK ) );

I2C_CLOCK_HI();
I2C_DATA_HI();

delay(1);
}

// Send a START Condition
//
void I2C_Start()
{
// set both to high at the same time
I2C_DDR &= ~( ( 1 << I2C_DAT ) | ( 1 << I2C_CLK ) );
delay(1);

I2C_DATA_LO();
delay(1);

I2C_CLOCK_LO();
delay(1);
}

// Send a STOP Condition
//
void I2C_Stop()
{
I2C_CLOCK_HI();
delay(1);

I2C_DATA_HI();
delay(1);
}

// write a byte to the I2C slave device
//
unsigned char I2C_Write( unsigned char c )
{
for ( char i=0;i<8;i++)
{
I2C_WriteBit( c & 128 );

c<<=1;
}

//return I2C_ReadBit();
return 0;
}


// read a byte from the I2C slave device
//
unsigned char I2C_Read( unsigned char ack )
{
unsigned char res = 0;

for ( char i=0;i<8;i++)
{
res <<= 1;
res |= I2C_ReadBit();
}

if ( ack > 0)
{
I2C_WriteBit( 0 );
}
else
{
I2C_WriteBit( 1 );
}

delay(1);

return res;
}

For those who want to use this on normal I2C devices, switch the commented lines in the I2C_Write function. I've tested it with an normal I2C slave and the library works for that. This code uses the internal pullups for both the SCL and SDA line. WARNING: don't use port 0 and 1 on non-Leonardo Arduinos. Those are used for serial communication.

With this code I can send the right waveforms (checked with an oscilloscope). However, I can't get a response from the device yet. I begin to suspect the device is broken.. But I suppose my programming question is solved now. Thanks for the help.