mastergetsi2c.c

Microchip的官方PIC24H系列16位单片机的外设源程序库。

#include <i2c.h>
#include <p30fxxxx.h>

/************************************************************************
*    Function Name:  MastergetsI2C
*    Description:    This routine reads predetermined data string length
*                    from the I2C bus.
*    Parameters:     unsigned int    : length
*                    unsigned char * : rdptr
*    Return Value:   unsigned int
*************************************************************************/

unsigned int MastergetsI2C(unsigned int length, unsigned char * rdptr, unsigned int i2c_data_wait)
{
    int wait = 0;
    while(length)                    /* Receive the number of bytes specified by length */
    {
        I2CCONbits.RCEN = 1;
        while(!DataRdyI2C())
        {
            if(wait < i2c_data_wait)
                wait++ ;                 
            else
            return(length);          /* Time out, return number of byte/word to be read */			
        }
        wait = 0;
        *rdptr = I2CRCV;             /* save byte received */
        rdptr++;
        length--;
        if(length == 0)              /* If last char, generate NACK sequence */
        {
            I2CCONbits.ACKDT = 1;
            I2CCONbits.ACKEN = 1;
        }
        else                         /* For other chars,generate ACK sequence */
        {
            I2CCONbits.ACKDT = 0;
            I2CCONbits.ACKEN = 1;
        }
            while(I2CCONbits.ACKEN == 1);    /* Wait till ACK/NACK sequence is over */
    }
    return 0;    /* return status that number of bytes specified by length was received */
}