Impossible to scan extended advertising data when the data size is bigger than 31 Bytes.

[j_delsol_catie]

Hello,

I need to scan the advertising data of my peripheral wich advertise with extended advertsing and LE coded PHY.

I use zephyr 3.7, and I work if I use the BLE controller from Zephyr but that doesn't work with SoftDevice controller... I'm limited to 31 Bytes.

If my advertising data is smaller than 32 Bytes, it works.

here my scan config.

struct bt_le_scan_param scan_param = {

.type = BT_LE_SCAN_TYPE_PASSIVE,

.options = BT_LE_SCAN_OPT_CODED,

.interval = BT_GAP_SCAN_FAST_INTERVAL,

.window = BT_GAP_SCAN_FAST_WINDOW,

};

my prj.conf for my cpunet firmware:

CONFIG_HEAP_MEM_POOL_SIZE=8192

CONFIG_MAIN_STACK_SIZE=2048

CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE=2048

CONFIG_MBOX=y

CONFIG_IPC_SERVICE=y

CONFIG_BT=y

CONFIG_BT_HCI_RAW=y

CONFIG_BT_CTLR_ASSERT_HANDLER=y

CONFIG_BT_MAX_CONN=16

# Enable and adjust the below value as necessary

# CONFIG_BT_BUF_EVT_RX_COUNT=16

# CONFIG_BT_BUF_EVT_RX_SIZE=255

# CONFIG_BT_BUF_ACL_RX_SIZE=255

# CONFIG_BT_BUF_ACL_TX_SIZE=251

# CONFIG_BT_BUF_CMD_TX_SIZE=255

CONFIG_BT_EXT_ADV=y

CONFIG_BT_CTLR_ADV_EXT=y

CONFIG_BT_CTLR_PHY_CODED=y

CONFIG_BT_CTLR_ADV_DATA_LEN_MAX=250

CONFIG_BT_CTLR_SCAN_DATA_LEN_MAX=255

CONFIG_ASSERT=y

CONFIG_DEBUG_INFO=y

CONFIG_EXCEPTION_STACK_TRACE=y

CONFIG_IPC_RADIO_BT=y

CONFIG_IPC_RADIO_BT_HCI_IPC=y

and my prj.conf for my cpuapp:

CONFIG_LOG=y

CONFIG_DK_LIBRARY=y

CONFIG_NCS_SAMPLES_DEFAULTS=y

CONFIG_HEAP_MEM_POOL_SIZE=4096

CONFIG_BT=y

CONFIG_BT_CENTRAL=y

CONFIG_BT_GATT_CLIENT=n

CONFIG_BT_HRS_CLIENT=n

CONFIG_BT_GATT_DM=n

CONFIG_BT_SCAN=y

CONFIG_BT_OBSERVER=y

CONFIG_BT_SCAN_FILTER_ENABLE=y

# CONFIG_BT_SCAN_UUID_CNT=1

CONFIG_BT_SCAN_MANUFACTURER_DATA_CNT=3

CONFIG_BT_SCAN_MANUFACTURER_DATA_MAX_LEN=255

CONFIG_BT_EXT_ADV=y

CONFIG_BT_USER_PHY_UPDATE=y

Do you have an idea ?

Thanks in advance.

Best regards,

julien

[dejans]

Hi Julien,

Are you limited to 31 bytes of advertising data when using SoftDevice Controller but not limited to 31 bytes if you use Zephyr controller?

Best regards,
Dejan

[j_delsol_catie]

Hi Dejan,

I'm limited only on the scanner device.
My advertiser device send 235 Bytes on the advertising data (I use MANUFACTURER_SPECIFIC_DATA type) with extended adv but my scanner device don't see them... however if I reduce, for example, the advertising data size to 31 Bytes, I see them with my scanner device.

If I use the Zephyr BLE controller for my advertiser device, I can't increase the adv_data size more than 191 Bytes (it's limited by the Zephyr BLE controller). So I use the SoftDevice controller.


Regards,

Julien

[j_delsol_catie]

[dejans]

Hi Julien,

Does scanning with both controllers work fine up until advertisement data length of 191 bytes? 

Does the problem occur only when scanning for advertisement data of the length 192 bytes and more in case when SoftDevice Controller is used?

Best regards,
Dejan

[j_delsol_catie]

Dejan,

Yes, it works with both controllers up to a data length of 191 bytes.

Yes, the problem occurs when the data length is greater than 191Bytes with the SoftDevice controller and even with Zephyr BLE controller.

Best regards,

Julien

[dejans]

Hi Julien,

You might need to do some changes to bt_data ad[] and start extended advertising using bt_le_ext_adv_start().
You can look at the following discussions - 1650 bytes periodic adv and advertising 1650 bytes of data. From provided sample (given in the second link), you can look at advertising data structure ad[] and create_advertising_chained().

Best regards,
Dejan

[j_delsol_catie]

Hi Dejan,

For my project I can't use the chained data. I need to send only one advertising data packet.

It works if I add this config in the application prj.conf:

CONFIG_BT_EXT_SCAN_BUF_SIZE=1650

# Zephyr Bluetooth LE Controller needs 16 event buffers to generate Extended

# Advertising Report for receiving the complete 1650 bytes of data

CONFIG_BT_BUF_EVT_RX_COUNT=16

# Set maximum scan data length for Extended Scanning in Bluetooth LE Controller

CONFIG_BT_CTLR_SCAN_DATA_LEN_MAX=1650

# Increase Zephyr Bluetooth LE Controller Rx buffer to receive complete chain

# of PDUs

CONFIG_BT_CTLR_RX_BUFFERS=9

I receive all data correctly on my scanner device.

Thank you for your support.

Best regards,

Julien

[dejans]

Hi Julien,

j_delsol_catie said:

I receive all data correctly on my scanner device.

This is great to hear. Thank you for providing modified prj.conf and for the status update.

Best regards,
Dejan