Xmega Application Note

twi_example.c

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//_____ I N C L U D E S ____________________________________________________

#include "avr_compiler.h"
#include "twi_slave_driver.h"

//_____ M A C R O S ________________________________________________________

//_____ D E F I N I T I O N ________________________________________________

extern void TWI_process(TWI_Slave_t* twi);

uint8_t twic_status_reg;
uint8_t twic_ctrla_reg;
uint8_t twic_ctrlb_reg;
uint8_t twic_data_reg;

#define SLAVE_ADDRESS    0x51

#define NUM_BYTES        8

/* Global variables */
TWI_Slave_t twiSlave;      
void TWIC_SlaveProcessData(void)
{
   PORTF.OUT=twiSlave.receivedData[twiSlave.bytesReceived];
   uint8_t recvData = twiSlave.receivedData[twiSlave.bytesReceived];
   twiSlave.sendData[twiSlave.bytesReceived] = recvData;

   //init first byte to write
   twic_data_reg =  twiSlave.sendData[0];
}

int main(void)
{
   /* Initialize PORTF for debug on STK600 */
   PORTF.DIRSET = 0xFF;
        
   // Configure LEDs for STK600
   PORTCFG.MPCMASK = 0xFF; // Configure several PINxCTRL registers at the same time
   PORTF.PIN0CTRL = PORT_INVEN_bm; // Invert input to turn the leds on when port output value is 1
   PORTF.OUT = 0x00;
   
   /* Set up interrupt mask on SCL pin */
   PORTC.INT0MASK = PIN1_bm;
        
   /* Initialize TWI slave. */
   TWI_SlaveInitializeDriver(&twiSlave, &TWIC, TWIC_SlaveProcessData);
   TWI_SlaveInitializeModule(&twiSlave,
                             SLAVE_ADDRESS,
                             TWI_SLAVE_INTLVL_HI_gc);   
   TWIC.SLAVE.CTRLA |= TWI_SLAVE_SMEN_bm;
        
   /* interrupt level. */
   PMIC.CTRL |= PMIC_HILVLEN_bm | PMIC_MEDLVLEN_bm;
   sei();
        
   do{
      //User application        
   }while (1);  
}

ISR(PORTC_INT0_vect)
{
   PORTC.INTFLAGS |= PORT_INT0IF_bm;
   PORTC.INTCTRL = PORT_INT0LVL_OFF_gc;

   TWI_process(&twiSlave);
}