[En-Nut-Discussion] TwMasterTransact is blocked

[CAMBON, Olivier]

Dear all,

I am a new user of the board Ethernut 2.1 ver C with Nut/OS 4.10.1.
In my system, the ethernut board drives some slave electronic using TWI
/ I2C bus.

I found in the documentation the API TwMasterRegRead and
TwMasterRegWrite but it seems that they are not implemented for AVR.
So, a wrote my own "i2c_get" and "i2c_set" API.

The problem is that sometimes, in the function "i2c_set", the call to
"TwMasterTransact" is blocked.
I tried with or without timeout. The result is the same. The
TwMasterTransact does NOT return.

I copy the source code of "i2c_get" and i2c_set".

Best regards,

Olivier.

/********************** I2C INIT **********************/
uint8_t i2c_init(void)
{
  uint32_t val = 0;

  /* Set the pin as input with pull-up */
  cbi(DDRD,0);
  cbi(DDRD,1);
  sbi(PORTD,0);
  sbi(PORTD,1);

  /* Set as I2C master */
  TwInit(1);
  /* Set the bus speed */
  val = 50000;
  TwIOCtl(TWI_SETSPEED, &val);

  return 0;
}

/********************** I2C GET **********************/
uint8_t i2c_get(uint8_t sla, uint8_t addr, uint8_t nb, uint8_t* data)
{
  int nb_rec = 0;
  int ret = 0;

  /* Check the pointer on data area */
  if(data==NULL) { return 6; }

  /* Do the exchange and check the returned number of data */
  nb_rec = TwMasterTransact(sla, &addr, (uint16_t) 1, data, (uint16_t)
nb, (uint32_t) 500);
  /* Check the error occurred */
  ret = TwMasterError();
  /* If an error is detected */
  if((nb_rec != nb) || (ret != 0))
  {
    /* If no error on transmission, set the returned value to indicate
that the error occurred on the number of data */
    if(ret == 0) { ret = 8; }
  }

  /* Clear the data if not received */
  if(nb_rec < 0) { nb_rec = 0; }
  while(nb_rec < nb ) { data[nb_rec] = 0; nb_rec++; }

  return ret;
}

/********************** I2C SET **********************/
uint8_t i2c_set(uint8_t sla, uint8_t addr, uint8_t nb, uint8_t* data)
{
  uint16_t i = 0;
  uint8_t* buff=NULL;
  int nb_rec = 0;
  int ret = 0;

  /* Check the pointer on the data area */
  if(data == NULL) { return 9; }
  /* Allocate a new area in order to build the frame */
  buff = malloc(nb+1);
  /* Check the allocation */
  if(buff == NULL) { return 10; }
  /* Copy the data to the new area */
  if(nb > 0) { for(i=0; i<nb; i++) { buff[i+1] = data[i]; } }
  /* But the first data is the destination address */
  buff[0] = addr;

  /* Execute the transmission */
  nb_rec = TwMasterTransact(sla, buff, (uint16_t) (((uint16_t)nb)+1),
NULL, (uint16_t) 0, (uint32_t) 100);
  /* Check the error occurred */
  ret = TwMasterError();
  /* If an error is detected */
  if((nb_rec != 0) || (ret != 0))
  {
    /* If no error on transmission, set the returned value to indicate
that the error occurred on the number of data */
    if(ret == 0) { ret = 11; }
  }

  /* Before to exit, free the allocated area */
  free(buff);

  return ret;
}


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