LoPy stops detecting BLE advertisements

[papasmurph]

Product: LoPy
Firmware: 1.6 something (updated a few days ago)

My test code logs all detected iBeacons (that use BLE). After a seemingly arbitrary time, but after maybe around an hour or so, it no longer detects any beacons. After a reset it works again.

get_adv returns, yet with nothing, so it doesn't hang. I'm aware of the max length of 8 for the buffer, but there's plenty of slack, so it doesn't fill up.

It also seems it misses detections while it works: If I use a beacon that pings each second, it will detect such pings for a while, then stop for a few seconds, then do it again. Hopefully there's no filtering or time window used. The beacon is very close, so it's always well within -60 dBm. At the same time I have many beacons out of range.

I've just added a timeout for silence, that calls start_scan again (if now that will work), but at that time I might have missed out on several detections already.

I don't believe it's hardware related, considering it immediately works again after reboot, but who am I to say.

from network import Bluetooth
import pycom
import time

pycom.heartbeat(False)

bluetooth = Bluetooth()
bluetooth.start_scan(-1)

timeSleep = 0.05
timeout = 0

while True:
    pycom.rgbled(0x202020)
    time.sleep(timeSleep)
    device = bluetooth.get_adv()
    if device != None:
        timeout = 0
        d = [b for b in device.data]
        rssi = device.rssi
        if rssi > -60 and d[5] == 0x4c and d[6] == 0x00 and d[7] == 0x02 and d[8] == 0x15:
            majorid = d[25] * 256 + d[26]
            minorid = d[27] * 256 + d[28]
            power = d[29]

            pycom.rgbled(0x008000)
            time.sleep(0.10)
            print(str(rssi) + '/' + str(majorid) + '/' + str(minorid) + '/' + str(power))            
        else:
            pycom.rgbled(0x000020)
            print('!')
    else:
        pycom.rgbled(0x200000)
        print('?')

        timeout += timeSleep + timeSleep
        if timeout > 10:
            bluetooth.start_scan(-1)
            timeout = 0

    time.sleep(timeSleep)

[livius]

@papasmurph
any change when you add in the loop

gc.collect()

above line? (add also import gc)

[papasmurph]

@livius So collect will not kick in anyway? I'll try it, but it seems like brute force considering the amount of calls and possible effects on timing.

[livius]

@papasmurph
Yes, but without you after some time get automatic call to gc.collect with longer wait time

then stop for a few seconds

and this can be the case

[papasmurph]

@livius Agreed, that could be the case for the short stops, even though garbage collection taking several seconds for such simple code seems strange. In any case, it doesn't explain the complete stop after a while. collect is added now for each loop and I removed the timeout. Let's see what happens.

[papasmurph]

@livius As far as I can see it's a real problem. After some time get_adv stops returning any data back, despite multiple beacons in close proximity. I tried calling start_scan again, but then the code stopped. I changed the code so it sleeps for a much shorter time. That way it keeps up with a huge margin. The gc.collect() is still there, but I hope I will not need it down the road. It also generally misses a lot of BLE advertisements, while a nearby phone doesn't.

[livius]

@papasmurph
Please report your findings here
https://github.com/pycom/pycom-micropython-sigfox/issues

[stef]

Same problem here , but solved it by perfoming a deepsleep beetween scans ( as deepsleep is acting like a reset).
I just finishing coding the same loop in C using ESP-IDF . will try it tomorow on a Generic ESP32 Board , will report here if i got the same bug . ( if not maybe that 's mean it's a Python Bug )

[Duane Kaufman]

Hello,

I recently started playing with my LoPy, and have a similar issue trying to harvest multiple advertisements at the same time.

Using other BLE tools, I know I have three devices advertising within range, yet I only get data from one of them when using code like in the Example for 'bluetooth.resolve_adv_data(data, data_type)' in the PyCom documentation.

In the Example code, how does one get a different advertising packet when calling bluetooth.get_adv()? Is it supposed to be simply chance timing that uncovers all of the device advertising that can be seen?

As you can probably tell, I am also a BLE newbie!

Thanks in advance!
Duane

[papasmurph]

@Duane-Kaufman I could detect multiple beacons. Note that they have to be kept apart to not interfere with each other. For each call to get_adv you get another advertisement from the queue, but the queue can only keep up to 8 values. Without any time.sleep (or at least very short), Python easily keeps up.

[Duane Kaufman]

@papasmurph Thanks for replying!

I'll keep in mind the physical separation issue. a couple of mine were pretty close together (but their advertisements should have been pretty asynchronous)

So, I should loop on get_adv until it returns None to exhaust it? I guess I never thought of that, but then again, the Example code should loop pretty fast on the get_adv call anyway?:

link to Example code

Sincerely,
Duane

[papasmurph]

@Duane-Kaufman I've noted that they can still completely "scramble" the communication. Yes, wait for None, and you should capture all if only the loop is fast enough.

[papasmurph]

@Duane-Kaufman I note that 1.7 works better in detecting pings, even though no enhancement was listed for this specifically. It remains to see if it ever stops scanning.

[stef]

@papasmurph
Some BT enhancement have been listed on the official ESP32 board for the last framework version .
My test with the last ESP Framework in C see no bug for BT detection even with more than 12h of scanning.
Will flash one of my lopy with 1.7 and report here the result.
Stéphane A.

[papasmurph]

@stef That sounds promising. I'm now testing it continuously.

[jmarcelino]

@papasmurph
Yes, BLE scan type has been changed to BLE_SCAN_TYPE_PASSIVE in the latest build which should help with beacons (at the cost of losing the device name for devices which only return it after a SCAN_REQ query from an active scan)

[papasmurph]

@jmarcelino Sadly, scanning (or detection) still stops though. After an hour or so get_adv stopped returning data, despite there being beacons close by that I hadn't moved. A hard reset got it started again.

[papasmurph]

@papasmurph When this happens, neither is it possible to attach to the LoPy's WiFi access point. My code still runs though.

[Duane Kaufman]

@papasmurph I think I might have a bad board, as I have not been able to get BLE to see devices I can detect with my phone around me. My code:

`from network import Bluetooth
import time
import binascii

bluetooth = Bluetooth()
bluetooth.init()

bluetooth.start_scan(20) # start scanning with 10s timeout
while bluetooth.isscanning():
time.sleep(1)
adv_list = []
adv_list = bluetooth.get_adv()
if adv_list != None:
for adv in adv_list:
print("Time: {0} adv.mac: {1}".format(time.time(), binascii.hexlify(adv.mac)))
else:
print("Time: {0} adv.mac: {1}".format(time.time(), "None"))
`
and I get:
MicroPython v1.8.6-607-g9c8a0e9e on 2017-05-01; LoPy with ESP32
Login as: micro
Password:
Login succeeded!
Type "help()" for more information.

import BLE_Raw
Time: 229 adv.mac: None
Time: 230 adv.mac: None
Time: 231 adv.mac: None
Time: 232 adv.mac: None
Time: 233 adv.mac: None
Time: 234 adv.mac: None
Time: 235 adv.mac: None
Time: 236 adv.mac: None
Time: 237 adv.mac: None
Time: 238 adv.mac: None
Time: 239 adv.mac: None
Time: 240 adv.mac: None
Time: 241 adv.mac: None
Time: 242 adv.mac: None
Time: 243 adv.mac: None
Time: 244 adv.mac: None
Time: 245 adv.mac: None
Time: 246 adv.mac: None
Time: 247 adv.mac: None
Time: 248 adv.mac: None`

Thanks for your review,
Duane
`

[papasmurph]

@Duane-Kaufman get_adv returns a single tuple, not an array, so "for" doesn't make sense here. See the code I posted initially.

Example: (mac=b'\xb4\x99Lm\x80\xcd', addr_type=0, adv_type=0, rssi=-87, data=b'\x02\x01\x06\x03\x02\xf0\xff\x15\xffBH\xcd\x80mL\x99\xb4\xa2@\x10\x01\x00\x00\xff\xff\x0f\xff\xff\xff\x00\x00')