twi.c

This fat 16 can be used for logging function. The user can use it for logger device.

****************************************************************************/
int8 rtc_set_date(int8 date, int8 month, int16 year)
{
    int8 date_array[4];
    int8 ret_val;
    date_array[0] = _FF_bin2bcd(date);
    date_array[1] = 0;
    date_array[2] = _FF_bin2bcd(month);
    if(year > 1999)
    {
        date_array[2] |= 0x80;
        year -= 2000;
    }
    else if(year > 1900)
        year -= 1900;
    date_array[3] = _FF_bin2bcd((uint8) year);
    _FF_cli();
    ret_val = twi_write(0x05, 4, date_array);
    _FF_sei();

    return(ret_val);
}

/****************************************************************************
**
** Gets the time and date from a Philips PCF8563 real-time clock 
**
** Parameters:  *hour, Pointer to where the RTC's hour will be stored
**              *min, Pointer to where the RTC's minute will be stored
**              *sec, Pointer to where the RTC's seconds value will be stored
**              *date, Pointer to where the RTC's day value will be stored
**              *month, Pointer to where the RTC's month value will be stored
**              *year, Pointer to where the RTC's year value will be stored
**
** Returns: 0 - Time/Date received successfully
**          1 - An error occurred
**
****************************************************************************/
int8 rtc_get_timeNdate(int8 *hour, int8 *min, int8 *sec, int8 *date, int8 *month, int16 *year)
{
    int8 time_array[8];
    int8 ret_val;

    ret_val = twi_read(0x02, 7, time_array);

    if(ret_val != TWI_SUCCESS)
        return(TWI_ERROR);

    twi_read(0x02, 7, time_array);

    *sec = _FF_bcd2bin(time_array[0] & 0x7F);
    *min = _FF_bcd2bin(time_array[1] & 0x7F);
    *hour = _FF_bcd2bin(time_array[2] & 0x3F);
    *date = _FF_bcd2bin(time_array[3] & 0x3F);
    *month = _FF_bcd2bin(time_array[5] & 0x1F);

    *year = _FF_bcd2bin(time_array[6]);
    if(time_array[5] & 0x80)
        *year += 2000;
    else
        *year += 1900;

    return(ret_val);
}


/*****************************************************************************
**
** LOCAL FUNCTIONS 
**
*****************************************************************************/

/****************************************************************************
**
** Sends a two wire interface command
**
** Parameters:  twcr_mask, Command to be sent
**              status, Flag to see if we need to wait for the status
**
** Returns: 0 - Command sent successfully
**          1 - An error occurred
**
****************************************************************************/
int8 twi_step(uint8 twcr_mask, uint8 status)
{
    uint8 twi_status;

    TWCR = twcr_mask | TWI_ENABLE;
    if(status != TWI_NO_WAIT)
    {
        TWITimer = 0;
        while(((TWCR & 0x80) == 0) && (TWITimer < 100))
            ;

        twi_status = (TWSR & 0xFC);

        if((status != TWI_IGNORE_STATUS) && ((twi_status != status) || ((TWCR & 0x80) == 0)))
        {
            TWCR = TWI_SEND_STOP | TWI_ENABLE;
            TWITimer = 0;
            while(((TWCR & 0x80) == 0) && (TWITimer < 100))
                ;
            return(TWI_ERROR);
        }
    }
    return(TWI_SUCCESS);
}

/****************************************************************************
**
** Reads the input number of bytes from the two wire interface
**
** Parameters:  addr, Address on the TWI bus the data will be read from
**              num_bytes, Number of bytes to read
**              *pntr, Pointer to the buffer that the data will be stored to
**
** Returns: 0 - Data read successfully
**          1 - An error occurred
**
****************************************************************************/
int8 twi_read(int8 addr, int8 num_bytes, int8 *pntr)
{
    int8 cnt;
    if(twi_step(TWI_SEND_START,0x08) != TWI_SUCCESS)
        return(TWI_ERROR);

    TWDR = 0xA2;    /* put in the address of the pfc */
    if(twi_step(TWI_CLOCK_DATA, 0x18) != TWI_SUCCESS)
        return(TWI_ERROR);

    TWDR = addr;    /* put in word address */
    if(twi_step(TWI_CLOCK_DATA,0x28) != TWI_SUCCESS)
        return(TWI_ERROR);

    if(twi_step(TWI_SEND_START,0x10) != TWI_SUCCESS)       /* send start...... */
        return(TWI_ERROR);

    TWDR = 0xA3;    /* put in the address of the pfc for read */
    if(twi_step(TWI_CLOCK_DATA,0x40) != TWI_SUCCESS)
        return(TWI_ERROR);

    for(cnt = 0; cnt < num_bytes; cnt++)
    {
        if(cnt != (num_bytes - 1))
        {
            if(twi_step(TWI_ACK_DATA, TWI_IGNORE_STATUS) != TWI_SUCCESS)
                return(TWI_ERROR);
        }
        else
        {
            if(twi_step(TWI_CLOCK_DATA, TWI_IGNORE_STATUS) != TWI_SUCCESS)
                return(TWI_ERROR);
        }

        #ifdef _IAR_EWAVR_
            *pntr = TWDR;
            pntr++;
        #else
            *pntr++ = TWDR;
        #endif
    }

    twi_step(TWI_SEND_STOP, TWI_NO_WAIT);    /* send stop */

    return(TWI_SUCCESS);
}


/****************************************************************************
**
** Writes the input number of bytes to the two wire interface
**
** Parameters:  addr, Address on the TWI bus the data will be written to
**              num_bytes, Number of bytes to write
**              *pntr, Pointer to the buffer that the data will be written
**                  from
**
** Returns: 0 - Data written successfully
**          1 - An error occurred
**
****************************************************************************/
int8 twi_write(int8 addr, int8 num_bytes, int8 *pntr)
{
    int8 cnt;

    if(twi_step(TWI_SEND_START, 0x08) != TWI_SUCCESS)
        return(TWI_ERROR);

    TWDR = 0xA2;    /* put in the address of the pfc */
    if(twi_step(TWI_CLOCK_DATA, 0x18) != TWI_SUCCESS)
        return(TWI_ERROR);

    TWDR = addr;    /* put in word address */
    if(twi_step(TWI_CLOCK_DATA, 0x28) != TWI_SUCCESS)
        return(TWI_ERROR);

    for(cnt = 0; cnt < num_bytes; cnt++)
    {
        #ifdef _IAR_EWAVR_
            TWDR = *pntr;
            pntr++;
        #else
            TWDR = *pntr++;
        #endif
        if(twi_step(TWI_CLOCK_DATA, 0x28) != TWI_SUCCESS)
            return(TWI_ERROR);
    }
    twi_step(TWI_SEND_STOP, TWI_NO_WAIT);

    return(TWI_SUCCESS);
}

/****************************************************************************
**
** Changes a binary value to a BCD value
**
** Parameters: binval, The input binary valued byte
**
** Returns: The BCD equivalent to the binary input
**
****************************************************************************/
int8 _FF_bin2bcd(uint8 binval)
{
    int8 temp_val;

    if(binval > 99)
       return((int8) EOF);

    temp_val = binval / 10;
    temp_val <<= 4;
    temp_val |= (binval % 10) & 0x0F;

    return(temp_val);
}

/****************************************************************************
**
** Changes a BCD value to a binary value
**
** Parameters: bcdval, The input BCD valued byte
**
** Returns: The binary equivalent to the BCD input
**
****************************************************************************/
uint8 _FF_bcd2bin(uint8 bcdval)
{
    uint8 temp_val;

    temp_val = ((bcdval >> 4) & 0x0F) * 10;
    temp_val += (bcdval & 0x0F);

    return(temp_val);
}

/*****************************************************************************
**
** EOF 
**
*****************************************************************************/