twi_example.c

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#include "twi.h"

/*
   NOTE: This example communicates with an external twi device with address 0x42.
   Keep in mind that external pull-ups on the twi data and clock lines are needed.
   Values around 5k should do nicely.
*/

#define CPU_HZ  20000000

/* This is a work around for the IAR EWAVR32, version 2.10B */
#ifdef __ICCAVR32__
        #define AVR32_TWI_SCL_0_PIN      7
        #define AVR32_TWI_SCL_0_FUNCTION 0
        #define AVR32_TWI_SDA_0_PIN      6
        #define AVR32_TWI_SDA_0_FUNCTION 0
#endif

#define WRITE 0 /* set to 1 for writing */
#define READ  0 /* set to 1 for reading */
#define SUCCESS  0
#define ERROR -1

typedef unsigned char avr32_piomap_t[][2];

/* prototype */
int pio_enable_module(avr32_piomap_t piomap, unsigned int size);


int main ( void )
{
  struct twi_options_t opt;
  struct twi_package_t package;
  
  int bytes;
  char buf_out[32] = "testing_testing\0";
  char buf_in[32];
  
  
  avr32_piomap_t twi_piomap = {                                 \
    {AVR32_TWI_SCL_0_PIN, AVR32_TWI_SCL_0_FUNCTION},            \
    {AVR32_TWI_SDA_0_PIN, AVR32_TWI_SDA_0_FUNCTION}             \
  };
  
  pio_enable_module(twi_piomap, 2);
  
  // TWI - 200kpbs, own address 0x42 (NOT USED)
  opt.cpu_hz = CPU_HZ;
  opt.speed = 200000;
  opt.twi_addr = 0x42;
  
  if( twi_init(&opt) != TWI_SUCCESS )
    return ERROR;
  
  /* master write */
  if (WRITE){
    package.chip = 0x34;                // Chip address for receiver
    package.addr = package.chip; // Address/command within the remote device
    package.addr_length = 0;         // Address/command length in bytes
    package.length = 4;     // Number of bytes in the data package
    package.buffer = buf_out;       // The data package itself
    
    bytes = twi_write(&package);
    if(bytes != package.length)
      return ERROR;
  }
  
  /* master read */
  if (READ){
    package.chip = 0x34;    // Chip address for receiver
    package.addr = package.chip; // Address/command within the remote device
    package.addr_length = 0;        // Address/command length in bytes
    package.length = 13;    // Number of bytes in the data package
    package.buffer = buf_in;        // The data package itself
    
    bytes = twi_read(&package);
    if(bytes != package.length)
      return ERROR;
  }
  
  return SUCCESS;
}


int pio_enable_module(avr32_piomap_t piomap, unsigned int size)
{
  int i;
  volatile struct avr32_pio_t *pio;

  /* get the base address for the port */
  switch (**piomap/32) {

  case 0:
    pio = &AVR32_PIOA;
    break;
  case 1:
    pio = &AVR32_PIOB;
    break;
  case 2:
    pio = &AVR32_PIOC;
    break;
  case 3:
    pio = &AVR32_PIOD;
    break;
  case 4:
    pio = &AVR32_PIOE;
    break;
  default :
    return ERROR;

  }

  for(i=0; i<size; i++){

    pio->pdr |= ( 1<<( (**piomap) % 32) );
    pio->pudr |= ( 1<<( (**piomap) % 32) );

    switch( *(*piomap+1) ){    
    case 0:
      pio->asr |= ( 1<<( (**piomap) % 32) );
      break;
    case 1:
      pio->bsr |= ( 1<<( (**piomap) % 32) );
      break;
    default:
      return ERROR;
    }

    ++piomap;

  }
  
  return SUCCESS;
}

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