BLE/PicoW: BLE advertisement fails as soon as I try to add manufacturer data

[vricosti]

Hi,
I am testing to declare a BLE uart peripheral and I am using examples/bluetooth/ble_uart_peripheral.py.

I have only modified the ble_advertising.py to add MANUFACTURER_DATA:

# Helpers for generating BLE advertising payloads.

from micropython import const
import struct
import bluetooth
import binascii

# Advertising payloads are repeated packets of the following form:
#   1 byte data length (N + 1)
#   1 byte type (see constants below)
#   N bytes type-specific data

_ADV_TYPE_FLAGS = const(0x01)
_ADV_TYPE_NAME = const(0x09)
_ADV_TYPE_UUID16_COMPLETE = const(0x3)
_ADV_TYPE_UUID32_COMPLETE = const(0x5)
_ADV_TYPE_UUID128_COMPLETE = const(0x7)
_ADV_TYPE_UUID16_MORE = const(0x2)
_ADV_TYPE_UUID32_MORE = const(0x4)
_ADV_TYPE_UUID128_MORE = const(0x6)
_ADV_TYPE_APPEARANCE = const(0x19)
_ADV_TYPE_MANUFACTURER_DATA = const(0xff)

# Generate a payload to be passed to gap_advertise(adv_data=...).
def advertising_payload(limited_disc=False, br_edr=False, name=None, services=None, manufacturerData=None, appearance=0):
    payload = bytearray()

    def _append(adv_type, value):
        nonlocal payload
        payload += struct.pack("BB", len(value) + 1, adv_type) + value

    _append(
        _ADV_TYPE_FLAGS,
        struct.pack("B", (0x01 if limited_disc else 0x02) + (0x18 if br_edr else 0x04)),
    )

    if name:
        _append(_ADV_TYPE_NAME, name)

    if services:
        for uuid in services:
            b = bytes(uuid)
            if len(b) == 2:
                _append(_ADV_TYPE_UUID16_COMPLETE, b)
            elif len(b) == 4:
                _append(_ADV_TYPE_UUID32_COMPLETE, b)
            elif len(b) == 16:
                _append(_ADV_TYPE_UUID128_COMPLETE, b)

    if manufacturerData:
        manufacturer_id, data_list = manufacturerData
        data_bytes = bytes(data_list)
        manufacturer_payload = struct.pack("<H", manufacturer_id) + data_bytes
        #_append(_ADV_TYPE_MANUFACTURER_DATA, manufacturer_payload)
        
    # See org.bluetooth.characteristic.gap.appearance.xml
    if appearance:
        _append(_ADV_TYPE_APPEARANCE, struct.pack("<h", appearance))

    return payload


def decode_field(payload, adv_type):
    i = 0
    result = []
    while i + 1 < len(payload):
        if payload[i + 1] == adv_type:
            result.append(payload[i + 2 : i + payload[i] + 1])
        i += 1 + payload[i]
    return result


def decode_name(payload):
    n = decode_field(payload, _ADV_TYPE_NAME)
    return str(n[0], "utf-8") if n else ""


def decode_services(payload):
    services = []
    for u in decode_field(payload, _ADV_TYPE_UUID16_COMPLETE):
        services.append(bluetooth.UUID(struct.unpack("<h", u)[0]))
    for u in decode_field(payload, _ADV_TYPE_UUID32_COMPLETE):
        services.append(bluetooth.UUID(struct.unpack("<d", u)[0]))
    for u in decode_field(payload, _ADV_TYPE_UUID128_COMPLETE):
        services.append(bluetooth.UUID(u))
    return services

def debug_adv(payload):
    #payload_hex = ''.join(format(x, '02x') for x in payload)
    payload_hex = binascii.hexlify(payload).decode('utf-8')
    print(payload_hex)
    print(decode_name(payload))
    print(decode_services(payload))
    
def demo():
    payload = advertising_payload(
        name="micropython",
        services=[bluetooth.UUID(0x180A),
                  bluetooth.UUID("6E400001-B5A3-F393-E0A9-E50E24DCCA9E")],
    )
    print(payload)
    print(decode_name(payload))
    print(decode_services(payload))


if __name__ == "__main__":
    demo()

and inside ble_uart_peripheral.py I am passing the data like this:

_MANUFACTURER_ID = 0x0D9D
_MANUFACTURER_DATA = [0x00, 0x01]
...

self._payload = advertising_payload(
            name=name,
            services=[_UART_UUID], 
            manufacturerData=(_MANUFACTURER_ID, _MANUFACTURER_DATA),
            appearance=None)

If I don't pass manufacturerData (manufacturerData=None) it works but it doesn't as soon as I assign my data.
What am I doing wrong ?

I have also tested to only advertise the _MANUFACTURER_ID without the associated data like that:

if manufacturerData:
        manufacturer_id, _ = manufacturerData
        manufacturer_payload = struct.pack("<H", manufacturer_id)
        _append(_ADV_TYPE_MANUFACTURER_DATA, manufacturer_payload)

but same problem

[vricosti]

nobody knows ?

[andrewleech]

It's been a few years since I worked with this stuff so I don't remember too clearly.

Why is this commented out?
#_append(_ADV_TYPE_MANUFACTURER_DATA, manufacturer_payload)

And when you say it stops working, what do you mean by that?

I think adding more to advertising usually means you need to go into the scan result packet, not much fits in the advertising packet alone

[vricosti]

yes I commented out to make it work temporarly, and when I say it doesnt work I mean I cannot detect the bluetooth device.
I am surprised about the size of allowed advertising data because on raspberry pi I can advertise this manufacturer data...