Issue with maximum size of ext adv data, CONFIG_BT_CTLR_ADV_DATA_LEN_MAX

[Mark G.]

Hi all,

I have an issue with achieving bigger sizes of ext adv data as 31 bytes.

My current BLE code is pretty much the same as the nrf_dm sample code:

https://github.com/nrfconnect/sdk-nrf/blob/main/samples/bluetooth/nrf_dm/src/main.c

I just want to add more data into the "sd[]" array / extended advertising data. But it seems the maximum size is 31 bytes. Although I set:

CONFIG_BT_EXT_ADV=y
CONFIG_BT_CTLR_ADV_DATA_LEN_MAX=192 

in my configuration. Following things I figured out:

The bitfield flag "BT_ADV_EXT_ADV" seems to not be set. Thus in adv.c, hci_set_adv_ext_complete() the total_data_len gets truncated to 31 bytes. The code will internally return that the advertising payload is too large. However when I force setting the flag, then the program will generate an error later on in bt_hci_cmd_send_sync with "W: opcode 0x2038 status 0x12" 

What is the correct way of increasing my advertising size?

[Hung Bui]

Hi Mark, 
Could you try to reproduce the code in one of our sample or provide a minimum sample that we can test here ? 

You can take a look at the peripheral_hr_coded (you can modify so that it uses 1Mbps instead of CODED) to see how extended advertising is used. 

[Mark G.]

Hi Hung Bui,

as mentioned It is reproducible on the nrf_dm example. I get this output from the device: (which is an nrf52833dk).

*** Booting nRF Connect SDK v3.0.1-9eb5615da66b ***
*** Using Zephyr OS v4.0.99-77f865b8f8d0 ***
Starting Distance Measurement sample
I: SoftDevice Controller build revision: 
I: 89 9a 50 8a 95 01 9c 58 |..P....X
I: fc 39 d2 c1 10 04 ee 02 |.9......
I: 64 ce 25 be             |d.%.    
I: HW Platform: Nordic Semiconductor (0x0002)
I: HW Variant: nRF52x (0x0002)
I: Firmware: Standard Bluetooth controller (0x00) Version 137.20634 Build 2617349514
I: Identity: C4:74:F6:86:20:61 (random)
I: HCI: version 6.0 (0x0e) revision 0x10f3, manufacturer 0x0059
I: LMP: version 6.0 (0x0e) subver 0x10f3
DM Bluetooth LE Synchronization initialization
E: Too big advertising data
Failed setting adv data (err -22)
Failed to start advertising (err -22)
Synchronisation init failed (err -22)

This is my diff to the nrf_dm sample on ncs 3.0.1.

git diff
diff --git a/samples/bluetooth/nrf_dm/prj.conf b/samples/bluetooth/nrf_dm/prj.conf
index 8b994dab81..24d3d51ede 100644
--- a/samples/bluetooth/nrf_dm/prj.conf
+++ b/samples/bluetooth/nrf_dm/prj.conf
@@ -36,3 +36,6 @@ CONFIG_NCS_SAMPLES_DEFAULTS=y
 CONFIG_DK_LIBRARY=y
 
 CONFIG_DM_HIGH_PRECISION_CALC=y
+
+CONFIG_BT_EXT_ADV=y
+CONFIG_BT_CTLR_ADV_DATA_LEN_MAX=192
diff --git a/samples/bluetooth/nrf_dm/src/main.c b/samples/bluetooth/nrf_dm/src/main.c
index ccb650a8e9..c8ae88a3ec 100644
--- a/samples/bluetooth/nrf_dm/src/main.c
+++ b/samples/bluetooth/nrf_dm/src/main.c
@@ -62,9 +62,12 @@ static const struct bt_data ad[] = {
        BT_DATA(BT_DATA_NAME_COMPLETE, DEVICE_NAME, DEVICE_NAME_LEN),
 };
 
+double posData[3] = {0, 1, 2};
 static const struct bt_data sd[] = {
        BT_DATA(BT_DATA_MANUFACTURER_DATA, (unsigned char *)&mfg_data, sizeof(mfg_data)),
        BT_DATA_BYTES(BT_DATA_UUID128_ALL, BT_UUID_DDFS_VAL),
+       BT_DATA(BT_DATA_INDOOR_POS, posData, sizeof(posData))
+
 };
 
 static struct bt_le_scan_param scan_param = {