static_i2c.h

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// Copyright 2012-2023 <>< Charles Lohr
// This file may be used for any purposes (commercial or private) just please leave this copyright notice in there
// somewhere.
 
// Generic I2C static library for AVRs (ATMega and ATTinys) (Commented out portion)
// Now, generic I2C library for any GPIO-based system.
 
// Include this in your .c file only!!!
// Include it after the following are defined:
 
// I2CDELAY_FUNC -> If you wish to override the internal delay functions.
// I2CSPEEDBASE -> define speed base multiplier 1 = normal, 10 = slow, .1 = fast; failure to define this will result in
// the clock being as fast as possible. I2CNEEDGETBYTE -> Do we need to be able to read data?
//
// I2CPREFIX   -> #define to be the prefix, i.e. BOB will cause  BOBConfigI2C to be generated.
// I2CNOSTATIC -> #define if you want the functions to be generated as not-static code.
//
// NOTE: You must initially configure the port to be outputs on both DSDA and DSCL and set them both to be driven high.
 
#ifndef I2CPREFIX
    #define I2CPREFIX
#endif
 
#ifndef I2CNOSTATIC
    #define I2CSTATICODE
#else
    #define I2CSTATICODE static
#endif
 
#ifndef I2CFNCOLLAPSE
    #define INTI2CFNCOLLAPSE(PFX, name) PFX##name
    #define I2CFNCOLLAPSE(PFX, name)    INTI2CFNCOLLAPSE(PFX, name)
#endif
 
#ifndef I2CNEEDGETBYTE
    #define I2CNEEDGETBYTE 1
#endif
 
#ifndef DSCL_IHIGH
    #define DSCL_IHIGH DSCL_INPUT
#endif
 
#ifndef DSDA_IHIGH
    #define DSDA_IHIGH DSDA_INPUT
#endif
 
I2CSTATICODE void I2CFNCOLLAPSE(I2CPREFIX, ConfigI2C)(){DSDA_IHIGH DSCL_IHIGH}
 
I2CSTATICODE void I2CFNCOLLAPSE(I2CPREFIX, SendStart)(){DELAY1 DSCL_IHIGH DELAY1 DSDA_OUTPUT DELAY1 DSCL_OUTPUT DELAY1}
 
I2CSTATICODE void I2CFNCOLLAPSE(I2CPREFIX, SendStop)(){DELAY1 DSDA_OUTPUT DELAY1 DSCL_IHIGH DELAY1 DSDA_IHIGH DELAY1}
 
// Return nonzero on failure.
I2CSTATICODE unsigned char I2CFNCOLLAPSE(I2CPREFIX, SendByte)(unsigned char data)
{
    unsigned int i;
    // Assume we are in a started state (DSCL = 0 & DSDA = 0)
 
    for (i = 0; i < 8; i++)
    {
        DELAY1
        if (data & 0x80)
        {
            DSDA_IHIGH
        }
        else
        {
            DSDA_OUTPUT
        }
        data <<= 1;
        DELAY2
        DSCL_IHIGH
        DELAY2
        DSCL_OUTPUT
    }
 
    // Immediately after sending last bit, open up DDDR for control.
    DELAY1
    DSDA_INPUT
    DELAY1
    DSCL_IHIGH
    DELAY1
    i = READ_DSDA;
    DELAY1
    DSCL_OUTPUT
    DELAY1
    return !!i;
}
 
#if I2CNEEDGETBYTE
 
I2CSTATICODE unsigned char I2CFNCOLLAPSE(I2CPREFIX, GetByte)(uint8_t send_nak)
{
    unsigned char i;
    unsigned char ret = 0;
 
    DSDA_INPUT
 
    for (i = 0; i < 8; i++)
    {
        DELAY1
        DSCL_IHIGH
        DELAY2
        ret <<= 1;
        if (READ_DSDA)
            ret |= 1;
        DSCL_OUTPUT
    }
 
    // Send ack.
    if (send_nak)
    {
    }
    else
    {
        DSDA_OUTPUT
    }
 
    DELAY1
    DSCL_IHIGH
    DELAY2
    DSCL_OUTPUT
    DELAY1
    DSDA_IHIGH
 
    return ret;
}
 
#endif