22.6.1 Host Transmission (7-bit Address)

Host Transmission (7-bit Address)

#include <xc.h>

#define mCLIENT_ADDRESS 0x4C
#define INIT 0
#define ADDRESS_PHASE 1
#define DATA_WRITE 2

#define PACKET_SIZE 10

unsigned char phase = INIT;

unsigned char hostTransmit[PACKET_SIZE] = {0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 0x88, 0x99, 0xAA};
unsigned char transmittedCount = 0;

int main(void) {
    
    /*Configure I2C pins as digital*/
    
    //I2C module has Host and Client functionality which may both be active at the same time.
    //In this example, Host functionality will be configured and used.
    
    //Configure baud rate for SCL @ 100kHz from 1/2 bus UPB clock @ 4MHz
    I2C2LBRG = 16; //Set low-time baud rate
    I2C2HBRG = 16; //Set high-time baud rate
    
    /* Configure Bus IDle timeout*/
    I2C2CON2bits.BITE = 1;
    I2C2BITObits.BITOTMR = 76;
    
    /* Configured interrupt enable bits*/
    I2C2INTCbits.HACKSIE = 1;       // Assert HSTIF on ACK seq
    I2C2INTCbits.HDTXIE = 1;        // Assert HSTIF on TX
    I2C2INTCbits.HSCIE = 1;         // Assert HSTIF on start
    I2C2INTCbits.HSTIE = 1;         // Assert I2CxIF when HSTIF is set
    I2C2CON2bits.PSZ = PACKET_SIZE; // Packet size
    I2C2CON2bits.EOPSC = 0b01;      // End of packet will be set after data bytes
    I2C2CON1bits.ON = 1;            // Enable I2C
    IFS2bits.I2C2IF = 0;            // Clear I2C general interrupt 
    IEC2bits.I2C2IE = 1;            // Enable I2C general interrupt

    /*wait for bus idle */
    while (!I2C2STAT2bits.BITO);
    phase = ADDRESS_PHASE;
    I2C2CON1bits.SEN = 1;          // Send Start bit

    while (1) {
        
        //Once data transmission is complete, repeat the operation.        
        if ((transmittedCount >= PACKET_SIZE) && (I2C2STAT2bits.STOPE)) {
            
            I2C2STAT2bits.STOPE = 0;    //Clear STOPE flag to detect next STOP
            I2C2STAT2bits.STARTE = 0;   //Clear STARTE flag since last START condition
            
            transmittedCount = 0;      //Start transmitting from start of data buffer
            
            I2C2CON2bits.NDA = 0;      //Will send address first, next byte is not data
            I2C2STAT2bits.EOP = 0;     //Clear end of packet bit
            I2C2CON2bits.PSZ = 10;     //Re-initialize packet size
            
            //Wait for bus idle
            while (!I2C2STAT2bits.BITO);
            phase = ADDRESS_PHASE;
            I2C2CON1bits.SEN = 1;     // Send Start bit
            
        }
    }
}

void __attribute__((interrupt, no_auto_psv)) _I2C2Interrupt(void) {
    IFS2bits.I2C2IF = 0;
    
    switch (phase) {
        case ADDRESS_PHASE: {
            /*Verify if start has been sent*/
            if (I2C2STAT2bits.STARTE) {
                /* Transmit client address with RW =0 , writing to client*/
                I2C2TRN = (mCLIENT_ADDRESS << 1) | 0;
                phase = DATA_WRITE;
            }
            break;
        }
        case DATA_WRITE: {
            /* Set NDA to indicate next byte is data */
            if (I2C2CON2bits.NDA != 1) {
                I2C2CON2bits.NDA = 1;
            }
            /* If Packet size is 0, EOP will be asserted,send STOP on EOP*/
            if (I2C2STAT2bits.EOP) {
                I2C2CON1bits.PEN = 1;
            } 
            else {
                if ((I2C2STAT1bits.ACKSTAT == 0) && (!I2C2STAT1bits.TBF) && (!I2C2STAT1bits.TRSTAT)) {
                    I2C2TRN = hostTransmit[transmittedCount++]; // Send data to client
                }
            }
            break;
        }
    }
}