LoPy stops detecting BLE advertisements

[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')

[Duane Kaufman]

@papasmurph Thanks for looking this over. Changed code to this, but still no response:

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 = bluetooth.get_adv()
	if adv_list != None:
		print("Time: {0} adv.rssi: {1}".format(time.time(), adv.rssi))
	else:
		print("Time: {0} adv.mac: {1}".format(time.time(), "None"))```

and I still get nothing :( as before

Duane

[papasmurph]

@Duane-Kaufman It works fine if you fix a few bugs. Well, at least it did for me.

from network import Bluetooth
import time

bluetooth = Bluetooth()
bluetooth.init()
bluetooth.start_scan(20)

while bluetooth.isscanning():
    adv_list = bluetooth.get_adv()
    if adv_list != None:
        print("Time: {0} adv.rssi: {1}".format(time.time(), adv_list.rssi))

    time.sleep(0.05)

print("I give up!")

[Duane Kaufman]

@papasmurph Using your code (modified a little :):

import time

bluetooth = Bluetooth()
bluetooth.init()
bluetooth.start_scan(20)

while bluetooth.isscanning():
    adv_list = bluetooth.get_adv()
    if adv_list != None:
        print("Time: {0} adv.rssi: {1}".format(time.time(), adv_list))

    time.sleep(1.0)

print("I give up!")```

I do not get anything (generally). Once in a great while, I will pick up one of the three BLE devices nearby, but probably only 1 in ten times I run the script.

Duane

[papasmurph]

@Duane-Kaufman I don't strictly see all advertisements either and after some time (randomly, but usually after an hour or so) it stops entirely, so something is wrong. In my own code I now use the event callback, which enables it to do other things in parallel, but it still happens though.

[RichardTXD]

@papasmurph
Hi.
I've been working on this, following your progress and the great community support - thanks. This is a show stopper for me if it can't be made to scan reliably 24/7.

Have you made progress?

I found that it just stops scanning early without an error message. I told it to scan for "-1" seconds = forever. I thought it was broken packets but I (currently) think that is wrong.

I've been tinkering with your code. I found it sensitive to putting in a gc.collect() just before fetching a packet (device = bluetooth.get etc) - that made the difference between scanning for approx 1 minute to many minutes (still going after 10 and I must leave the office).
Much more testing required.

[papasmurph]

@RichardTXD With callback to an event handler it can work for an hour or so, but still eventually stops. It's time Pycom takes a look at it.

[stef]

@papasmurph ,
I confirm that , still stoping after time . nothing to do but reset.
New firmware doesn't matter .

[RichardTXD]

@papasmurph
I am Running WiPy 2.0 with latest firmware flashed yesterday.
Windows 7 and Atom. I'm using an expansion board.
I set my PC to not shutdown/go to sleep etc.

Hi. There is also a concern with callback. I tried it also. Then I went back to a non-call back program. The callback was still triggering.
It would appear that unless you press reset of the board, the callback lingers in memory.
I would not be surprised at a difference. I'm guessing memory is deallocated when the callback is terminated and that may be at the heart of it all.

@stef
Hi. You are quite correct. It is unstable.
I've seen different crashes depending on if garbage collection is done. If I don't garbage collect it seems to crash quicker - I will go back to testing that later.

I'm still trying to get a feel for how and where it crashes but so far it seems random - a few hours to tens of minutes.

I modded the program to tell me how many beacons were received. I have a lot of beacons in the office. I empty the queue on each iteration.

I did 3 tests late yesterday.
I set it to scan for -1 seconds = infinitely
There is a garbage collection before each read of bluetooth into its variable.
I press reset between each program run
Test-1. It received 103,139 beacons and failed after about 2.5 hours
Test-2. It received 17,094 beacons and failed - not all that long.
Test-3. It received 31,945 beacons and failed.
Each fail was the code hanging up. Stopped.
I just now put in an elapsed seconds on the end of each result.
The outer while loop repeats till it is not scanning. An inner loop empties the queue. I assume it was still scanning, yet nothing was received.

Until we get past this issue, I can't ship product of course, same as others I suppose. I'm trying to think of a workaround.