scanning while advertising causes NRF_ERROR_BUSY: _bleio.BluetoothError: Unknown system firmware error: 0011

[awgrover]

Several examples are available that show scanning while advertising (i.e. no stop_advertising). E.g. Clue rock-paper-scissors, and some non circuitpython examples for the nRF52840 (e.g. https://learn.adafruit.com/introducing-the-adafruit-nrf52840-feather/dual-roles-bleuart).

On the bluefruit at .start_scan(), I get "_bleio.BluetoothError: Unknown system firmware error: 0011", which is NRF_ERROR_BUSY, implying scanning can't occur during advertising. I can find no other report of this error (which seems odd). Code works under circuitpython 6.3.0.

This appears to be some change in _bleio in 7.x.x (since 6.3.0).

Hardware, as reported in boot_out.txt:
Adafruit Circuit Playground Bluefruit with nRF52840
Board ID:circuitplayground_bluefruit

circuitpython, as reported in boot_out.txt and repl:
Adafruit CircuitPython 7.1.1 on 2022-01-14; Adafruit Circuit Playground Bluefruit with nRF52840

only 1 library in lib/ folder:
adafruit-circuitpython-ble-7.x-mpy-8.2.0/lib/adafruit_ble
reported by repl:

>>> import adafruit_ble
>>> print( adafruit_ble.__version__ )
8.2.0

(I tried the "simple game" of Clue rock-paper-scissors, same error.)
Circuitpython vs adafruit_ble matrix:

                        adafruit_ble
                        8.2.0   8.1.0   7.3.4
circuitpython
7.1.1                   fail    fail    fail
en_US-20220210-c234d92  fail            fail
6.3.0                   works           works

example code

import traceback # remove for circuitpython 6.3.0
import time

import _bleio # for the exception
from adafruit_ble import BLERadio
from adafruit_ble.advertising import Advertisement

print("\nstart")

MAX_SEND_TIME_S = 5

# 20ms is the minimum delay between advertising packets
# in Bluetooth Low Energy
# extra 10us deals with API floating point rounding issues
MIN_AD_INTERVAL = 0.02001 # changing has no effect

ble = BLERadio()

advertisement = Advertisement()
advertisement.short_name = "HELLO"
advertisement.connectable = False # True has no effect

print("loop")

# related to the previous bonding? no
# ble._adapter.erase_bonding()

# advertise while scanning:
ble.start_advertising(advertisement, interval= MIN_AD_INTERVAL)

while True:
    # does waiting have any effect? no
    # time.sleep(0.2)

    # Timeout value is in seconds
    # window and interval are 0.1 by default - same value means
    # continuous scanning (sending Advertisement will interrupt this)
    gotit = 10
    while(gotit > 0):
        try:
            # the .start_scan() will throw:
            # Traceback (most recent call last):
            #   File "code.py", line 47, in <module>
            #   File "adafruit_ble/__init__.py", line 250, in start_scan
            # _bleio.BluetoothError: Unknown system firmware error: 0011

            for adv in ble.start_scan(
                                      Advertisement,
                                      # does non-continuous have any effect? no
                                      #window=0.1,
                                      #interval=0.2,
                                      #minimum_rssi=-90,
                                      # does a buffer have any effect? no
                                      #buffer=256,
                                      # does a timeout have any effect? no
                                      # timeout=MAX_SEND_TIME_S
                                      ):
                gotit = 0
                print("received: ", adv.short_name)

                ble.stop_scan()

                break
        except _bleio.BluetoothError as e:
            # does retrying have any effect? no

            # should we have done a stop_scan for retry? no
            #ble.stop_scan()
            gotit -= 1
            time.sleep(0.03)
            if (gotit==9): # we don't need to see it 10 times
                print( traceback.format_exception( None, e, e.__traceback__) )
            print("fail...",gotit, e) # fails 0..9
    if gotit == 0:
        print("Failed")
        break

[tannewt]

This seems like a core issue. Moving it to the core repo.

[tannewt]

I think this is due to 7.0 loading the peer keys for resolving addresses. IIRC the soft device only has one key store and we load different keys depending on whether we are a central or peripheral. Maybe we can load both sets at once to allow concurrent scanning and advertising.

@awgrover Do you have devices bonded to you when you are doing both scanning and advertising?

[awgrover]

@tannewt No devices are bonded. I tried ble._adapter.erase_bonding() which had no effect.

[tannewt]

Thanks! I'll try to look into this in the next few weeks.

[dhalbert]

Could have key store load everything, or check that there is no bonding.

[kevinjwalters]

I've just noticed this on 7.2.0, I tried break on a start_scan() for loop and got this, thought I could work around it by waiting for the timeout to drop out of the for loop but that doesn't work either.

[kevinjwalters]

I think it does it all the time:

Press any key to enter the REPL. Use CTRL-D to reload.

Adafruit CircuitPython 7.2.0 on 2022-02-24; Adafruit CLUE nRF52840 Express with nRF52840
>>>
>>> from adafruit_ble import BLERadio
>>> from adafruit_ble.advertising.adafruit import AdafruitColor
>>> ca = AdafruitColor()
>>> ca.color = 0x778899
>>> radio = BLERadio()
>>> for adv in radio.start_scan(timeout=3.0):
...     pass
...
...
...
>>> radio.start_advertising(ca)
>>> for adv in radio.start_scan(timeout=3.0):
...     pass
...
...
...
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "adafruit_ble/__init__.py", line 250, in start_scan
_bleio.BluetoothError: Unknown system firmware error: 0011