Bluepy BLE Disconnecting after receiving several packets from Bluno Beetle

Question

I am required to connect 6 bluno beetles to my Raspi 3B+ to receive some data concurrently. However, with only 1 connection to one bluno beetle, I am already having constant disconnection after receiving a few packets. Sometimes I am able to receive 20 packets before disconnecting, while sometimes I am able to receive 5 packets before disconnecting. The number of packets received fluctuates.

Is this suppose to be normal?

My raspi 3B+ is installed with Raspbian GNU/Linux 10 (buster). I have python3 installed with bluepy version 1.3.0 installed.

The Bluno Beetle is an Arduino Uno based board with bluetooth 4.0 The Raspi 3B+ has a Bluetooth HCI Version: 5.0 (0x9)

I have tried to handle disconnection by reconnecting and it works fine. But the time taken to reconnect takes a while (4-5 seconds) which I would have data from Bluno beetle side.

How can I further enhance the robustness of BLE? This is my python code below where I am only listening to data sent from the Bluno Beetle.

from bluepy import btle
from bluepy.btle import BTLEException, Scanner, BTLEDisconnectError
import threading

# Global Vars
connectionObjects = []      # Total of 6 Connections expected
connectedThreads = []       # Total of 6 Connections expected

threads = list()

class MyDelegate(btle. DefaultDelegate):
    def __init__(self, connection_index):
        btle.DefaultDelegate.__init__(self)

    def handleNotification(self, cHandle, data):
        print("handling notification...")
        data_string = str(data)
        print(data_string)

class ConnectionHandlerThread (threading.Thread):

    def __init__(self, connection_index, BTAddress):
        threading.Thread.__init__(self)
        self.connection_index = connection_index
        self.BTAddress = BTAddress
        self.connection = connectionObjects[self.connection_index]

    def connect(self):
        self.connection.setDelegate(MyDelegate(self.connection_index))

    def run(self):
        self.connect()
        while True:
            try:
                if self.connection.waitForNotifications(1.0):
                    continue
                print("Waiting...")
            except:
                try:
                    self.connection.disconnect()
                except:
                    pass
                finally:
                    reestablish_connection(self.connection, self.BTAddress, self.connection_index)

def reestablish_connection (connection, BTAddr, index):
    while True:
        try:
            print("trying to reconnect with " + str(BTAddr) )
            connection.connect(str(BTAddr))
            print("re-connected to "+ str(BTAddr) +", index = " + str(index))
            return
        except:
            continue

BTAddress = ['1c:ba:8c:1d:3a:c1']

for index in range(len(BTAddress)):
    while True:
        try:
            p = btle.Peripheral()
            p.connect(BTAddress[index], btle.ADDR_TYPE_PUBLIC)
            break
        except btle.BTLEException as e:
            print("Connection Fail. Retrying now...")
            continue

    print ("Successful Connection to BLE " + str(BTAddress[index]))
    connectionObjects.append(p) # first index is 0, first connected is beetle num 1
    thread = ConnectionHandlerThread(len(connectionObjects)-1, BTAddress[index])
    thread.setName("BLE-Thread-" + str(len(connectionObjects)-1))
    thread.start()
    connectedThreads.append(thread)

My hciconfig:

hci0:   Type: Primary  Bus: UART
        BD Address: B8:27:EB:D4:EC:5D  ACL MTU: 1021:8  SCO MTU: 64:1
        UP RUNNING
        RX bytes:204543 acl:2383 sco:0 events:8342 errors:0
        TX bytes:49523 acl:152 sco:0 commands:4072 errors:0

Connecting via bluetoothctl seems fine:

root@raspberrypi:~# bluetoothctl
Agent registered
[bluetooth]# connect 1c:ba:8c:1d:3a:c1
Attempting to connect to 1c:ba:8c:1d:3a:c1
[CHG] Device 1C:BA:8C:1D:3A:C1 Connected: yes
Connection successful

I have been searching around the net for a robust solution but could not find a way to prevent disconnection or increase the reconnection time. Would appreciate if you could help me with this!

Could the reason be RPI firmaware makes BLE unstable?? https://github.com/IanHarvey/bluepy/issues/396

Answer 1

I can conclude that RPI firmware has issue after testing with another board.

Could the reason be RPI firmaware makes BLE unstable?? https://github.com/IanHarvey/bluepy/issues/396

Works without disconnection when tested the same setup with Ultra96 v2 running on Ubuntu 18.04 bionic. I am able to read/write to bluno device every 1ms and the connection is robust.

Hence, it seems like the problem was with RPI firmware. I was using Rasbian Buster on Raspberry pi 3b+.