how to bt_scan_filter_add by short name ?

[stevenlin]

hi all

how to bt scan filter by short name ?

i have been set "#define CONFIG_BT_SCAN_SHORT_NAME_CNT 1"

it get bus fault error:

"Bluetooth ready
***** BUS FAULT *****
  Precise data bus error
  BFAR Address: 0x72616d53
***** Hardware exception *****"

bt_scan_filter_add

const char bleDeviceName[]="myBLEdevice";

err = bt_scan_filter_add(BT_SCAN_FILTER_TYPE_SHORT_NAME, bleDeviceName);
    if (err) {
                printk("error = %d\n",err);
        printk("Scanning filters cannot be set\n");
        return;
    }

autoconfig.h

#define CONFIG_BT_GATT_DM 1
#define CONFIG_BT_GATT_DM_MAX_ATTRS 35
#define CONFIG_BT_GATT_DM_MAX_MEM_CHUNKS 6
#define CONFIG_BT_SCAN 1
#define CONFIG_BT_SCAN_NAME_MAX_LEN 32
#define CONFIG_BT_SCAN_SHORT_NAME_MAX_LEN 32
#define CONFIG_BT_SCAN_FILTER_ENABLE 1
#define CONFIG_BT_SCAN_MANUFACTURER_DATA_MAX_LEN 32
#define CONFIG_BT_SCAN_UUID_CNT 0
#define CONFIG_BT_SCAN_NAME_CNT 0
#define CONFIG_BT_SCAN_SHORT_NAME_CNT 1
#define CONFIG_BT_SCAN_ADDRESS_CNT 0
#define CONFIG_BT_SCAN_APPEARANCE_CNT 0
#define CONFIG_BT_SCAN_MANUFACTURER_DATA_CNT 0

[Jackson Wilson]

Any answer?  I have exactly the same question!

[scath]

Hoping we can get some help on this.

The "documentation" on this feature (such as it is) can be found here. However, it doesn't describe how to pass a short name as a filter.

Worse, the filter doesn't appear to work at all. Not really surprised - A LOT of their code doesn't work as documented (when it's even documented at all).

If you dig into the actual header file, you'll note that `bt_scan_filter_add()` takes a void pointer for the value to filter on, which is cast on execution.

int bt_scan_filter_add(enum bt_scan_filter_type type,
		       const void *data)
{
	char *name;
	struct bt_scan_short_name *short_name;
	bt_addr_le_t *addr;
	struct bt_uuid *uuid;
	uint16_t appearance;
	struct bt_scan_manufacturer_data *manufacturer_data;
	int err = 0;

	if (!data) {
		return -EINVAL;
	}

	k_mutex_lock(&scan_mutex, K_FOREVER);

	switch (type) {
	case BT_SCAN_FILTER_TYPE_NAME:
		name = (char *)data;
		err = scan_name_filter_add(name);
		break;

	case BT_SCAN_FILTER_TYPE_SHORT_NAME:
		short_name = (struct bt_scan_short_name *)data;
		err = scan_short_name_filter_add(short_name);
		break;

	case BT_SCAN_FILTER_TYPE_ADDR:
		addr = (bt_addr_le_t *)data;
		err = scan_addr_filter_add(addr);
		break;

	case BT_SCAN_FILTER_TYPE_UUID:
		uuid = (struct bt_uuid *)data;
		err = scan_uuid_filter_add(uuid);
		break;

	case BT_SCAN_FILTER_TYPE_APPEARANCE:
		appearance = *((uint16_t *)data);
		err = scan_appearance_filter_add(appearance);
		break;

	case BT_SCAN_FILTER_TYPE_MANUFACTURER_DATA:
		manufacturer_data = (struct bt_scan_manufacturer_data *)data;
		err = scan_manufacturer_data_filter_add(manufacturer_data);
		break;

	default:
		err = -EINVAL;
		break;
	}

	k_mutex_unlock(&scan_mutex);

	return err;
}

The important line is `case BT_SCAN_FILTER_TYPE_SHORT_NAME:`

You'll see that `short_name` is cast to `struct bt_scan_short_name`. That struct is as follows:

/**@brief A helper structure to set filters for the name.
 */
struct bt_scan_short_name {
	/** Pointer to the short name. */
	const char *name;

	/** Minimum length of the short name. */
	uint8_t min_len;
};

Putting that all together, you *should* be able to set a short name filter with _something_ like:

    struct bt_scan_short_name ble_shrt_name;
	ble_shrt_name.name = "shrtname";
	ble_shrt_name.min_len = 8;
	err = bt_scan_filter_add(BT_SCAN_FILTER_TYPE_SHORT_NAME, &ble_shrt_name );
	if (err) {
		printk("\nScanning filters cannot be set (err %d)\n", err);
		return err;
	}

	err = bt_scan_filter_enable(BT_SCAN_SHORT_NAME_FILTER, false);
	if (err) {
		printk("\nFilters cannot be turned on (err %d)\n", err);
		return err;
	}

Edit: This still requires you to set the number of Short Name Filters in the `guiconfig` or `menuconfig` via `BT_SCAN_SHORT_NAME_CNT`.

Very sad that Nordic hasn't really documented this very well, and doesn't appear to be listening to people asking for guidance.

I wonder if they'll step up now.