Creating fields <= hook_install()

  // Create fields.
  $fields = array();

  $fields['example_unit_count'] = array(
    'field_name' => 'example_unit_count',
    'type' => 'number_integer',
    // Optional.
    'cardinality' => 1,
    'settings' => array(
      'max_length' => 5,
    ),
  );

  $fields['example_latitude'] = array(
    'field_name' => 'example_latitude',
    'type' => 'number_float',
    'settings' => array(
      'max_length' => 20,
    ),
  );

  $fields['example_longitude'] = array(
    'field_name' => 'example_longitude',
    'type' => 'number_float',
    'settings' => array(
      'max_length' => 20,
    ),
  );

  $fields['example_turbine_manufacturer'] = array(
    'field_name' => 'example_turbine_manufacturer',
    'type' => 'text',
    'settings' => array(
      'max_length' => 60,
    ),
  );

  foreach ($fields as $field) {
    field_create_field($field);
  }

  // Create Field Instances.
  $instances = array();

  $instances['example_unit_count'] = array(
    'field_name' => 'example_unit_count',
    'label' => $t('Number of Units'),
    'description' => $t('Number of individual units at a given Facility'),
    'widget' => array(
      'type' => 'text_textfield',
    ),
    'required' => TRUE,
    'settings' => array(
      'text_processing' => 0,
    ),
  );

  $instances['example_latitude'] = array(
    'field_name' => 'example_latitude',
    'label' => $t('Latitude'),
    'description' => $t('Signed degrees format (DDD.dddd)'),
    'widget' => array(
      'type' => 'text_textfield',
    ),
    'settings' => array(
      'text_processing' => 0,
    ),
    'display' => array(
      'default' => array(
        'type' => 'hidden',
      ),
    ),
  );

  $instances['example_longitude'] = array(
    'field_name' => 'example_longitude',
    'label' => $t('Longitude'),
    'description' => $t('Signed degrees format (DDD.dddd)'),
    'widget' => array(
      'type' => 'text_textfield',
    ),
    'settings' => array(
      'text_processing' => 0,
    ),
    'display' => array(
      'default' => array(
        'type' => 'hidden',
      ),
    ),
  );

  $instances['example_turbine_manufacturer'] = array(
    'field_name' => 'example_turbine_manufacturer',
    'label' => $t('Turbine Manufacturer'),
    'description' => $t('The name of the turbine manufacturer'),
    'widget' => array(
      'type' => 'text_textfield',
    ),
    'display' => array(
      'default' => array(
        'label' => 'inline',
      ),
    ),
  );

  foreach ($instances as $instance) {
    $instance['entity_type'] = 'node';
    $instance['bundle'] = 'example';
    field_create_instance($instance);
  }
}