Method grove_i2c_start

Software/C/GoPiGo3.cpp:437–486

}

int GoPiGo3::grove_i2c_start(uint8_t port, i2c_struct_t *i2c_struct){
  uint8_t msg_type;
  uint8_t port_index;
  switch(port){
    case GROVE_1:
      msg_type = GPGSPI_MESSAGE_START_GROVE_I2C_1;
      port_index = 0;
    break;
    case GROVE_2:
      msg_type = GPGSPI_MESSAGE_START_GROVE_I2C_2;
      port_index = 1;
    break;
    default:
      fatal_error("grove_i2c_start error. Must be one grove port at a time. GROVE_1 or GROVE_2.");
  }
  spi_array_out[0] = Address;
  spi_array_out[1] = msg_type;
  spi_array_out[2] = ((i2c_struct->address & 0x7F) << 1);

  if(i2c_struct->length_read > LONGEST_I2C_TRANSFER){
    i2c_struct->length_read = LONGEST_I2C_TRANSFER;
  }
  spi_array_out[3] = i2c_struct->length_read;
  GroveI2CInBytes[port_index] = i2c_struct->length_read;

  if(i2c_struct->length_write > LONGEST_I2C_TRANSFER){
    i2c_struct->length_write = LONGEST_I2C_TRANSFER;
  }
  spi_array_out[4] = i2c_struct->length_write;

  for(uint8_t i = 0; i < i2c_struct->length_write; i++){
    spi_array_out[5 + i] = i2c_struct->buffer_write[i];
  }

  // assign error to the value returned by spi_transfer_array, and if not 0:
  if(int error = spi_transfer_array((5 + i2c_struct->length_write), spi_array_out, spi_array_in)){
    return error;
  }

  // If the fourth byte received is not 0xA5
  if(spi_array_in[3] != 0xA5){
    return ERROR_SPI_RESPONSE;
  }
  // If the fifth byte received is not GROVE_STATUS_VALID_DATA
  if(spi_array_in[4] != GROVE_STATUS_VALID_DATA){
    return spi_array_in[4];
  }

  return ERROR_NONE;
}

int GoPiGo3::get_grove_value(uint8_t port, void *value_ptr){
  uint8_t msg_type;