nRf52832 bluetooth extended advertisement using nrf connect for vscode

[ShahzaibShamim]

I am exploring the 'central_and_peripheral_hr' example in nRF Connect for VS code. By modifying the given example slightly, I am able to advertise 16 bytes of data in the 'ManufacturerSpecificData' field. I have read on DevZone that the limit for a standard packet is 31 bytes and up to 255 bytes in extended packet type. I also observed that when I change the number of bytes to 24 then no BT device is found. However, I could not find any helpful examples related to this. I have also checked the periodic advertising example, but I have not been able to find any devices using that example.
I am using the nRF52-52832dk as a scanner with the Bluetooth LE app in nRF Connect for Desktop, and another nRF52-52832dk as my main board to advertise data. Here is a part of my code:

int res;

res = bt_le_adv_stop();
if(res)
{
	printk("************ADV STOP failed!************\n");
	return;
}
printk("************ADV STOP successful!************\n");

struct bt_data dt_bt_ad[] = {
	BT_DATA_BYTES(BT_DATA_GAP_APPEARANCE),
	BT_DATA_BYTES(BT_DATA_FLAGS, (BT_LE_AD_GENERAL | BT_LE_AD_NO_BREDR)),
	BT_DATA(BT_DATA_MANUFACTURER_DATA, myDataBytes, sizeof(myDataBytes)),
};

res = bt_le_adv_start(BT_LE_ADV_CONN, dt_bt_ad, ARRAY_SIZE(dt_bt_ad), sd, ARRAY_SIZE(sd));
if (res) {
	printk("Advertising failed to start (err %d)\n", res);
	return;
}
printk("Advertising started\n");

[Sigurd]

Hi,

I also observed that when I change the number of bytes to 24 then no BT device is found

Did you get any error codes when this happened? Likely you are hitting the 31 byte limit. Note that also have BT_DATA_FLAGS and BT_DATA_GAP_APPEARANCE in your advertising packet, and that this also takes some bytes.

[ShahzaibShamim]

How can I advertise more data bytes like up to 250 using the Manufacturer Specific Data type in extended form. Any code nrf connect for vscode example would be very helpful.

Thanks

[Sigurd]

Hi,

ShahzaibShamim said:

. Any code nrf connect for vscode example would be very helpful.

Take a look at this sample: https://github.com/nrfconnect/sdk-zephyr/tree/main/samples/bluetooth/broadcaster_multiple

[ShahzaibShamim]

I tried the example you mentioned. In the code, I am adding some bytes in array.

static uint8_t mfg_data[BT_MFG_DATA_LEN] = { 0xFF, 0xFF };  // original
static uint8_t mfg_data[BT_MFG_DATA_LEN] = { 0xFF, 0xFF, 0x01, 0x02, 0x03, 0x04};   // bytes added

And for scanning, I am using another nrf52dk with an observer example. On serial terminal, I can see various parameters but where can I see the data that I have added? Because I also want to update this data at runtime and on central side I want to extract this data after scanning and do some tasks depending on what the peripheral is advertising.

[Sigurd]

In the scan_recv callback, you need to call bt_data_parse(), where you have a data_cb(). In the data_cb() you can check the data. See https://github.com/nrfconnect/sdk-zephyr/blob/main/samples/bluetooth/observer/src/observer.c#L25

Maybe the code here can help you to parse the manufacturer data : https://github.com/nrfconnect/sdk-nrf/blob/v2.2.0/samples/bluetooth/nrf_dm/src/main.c#L94