Reading data from bluetooth device

[sam_uk]

Hi I've done a search but it's a bit unclear to me what the current state of bluetooth support is.

Am I likely to have success connecting this device https://wiki.hackerspace.pl/projects:xiaomi-flora

It looks like I need
sudo apt-get install python-pip
pip install paho-mqtt
pip install gattlib

Are these supported on LoPy?

[luc hanneuse]

@seb

I write this code to be able to find where it doesn't work

from network import Bluetooth
import time
bt = Bluetooth()

print("searching")
bt.start_scan(-1)

print("connection")
conn = bt.connect('C47C8D643FAF')

print("connected")


def characteristic_callback(char):
    v = int.from_bytes(char.value(), "little")
    print("Got new value: {}".format(v))

print("before services")
services = conn.services()
print("services")
for service in services:
    print("Service: {}".format(service.uuid()))
    if service.uuid() == b'XXXXXXXXXXXXX':
        characteristics = service.characteristics()
        for characteristic in characteristics:
            print("Characteristic: {}".format(characteristic.uuid()))
            if characteristic.uuid() == b'XXXXXXXXXXXX':
                characteristic.callback(trigger=Bluetooth.CHAR_NOTIFY_EVENT,
                                        handler=characteristic_callback,
                                        arg=None)

So, in the terminal it print
searching
connection
connected
before services

So it never reach the line :

services = conn.services()

in the page https://wiki.hackerspace.pl/projects:xiaomi-flora , it's specified that "You need to write 0xA01F to the handle 0x0033 to enable real-time data reading "

How can I write the value 0xA01F in the handle 0x0033 ?

Thanks in advance for your precious help.

[seb]

Hi,

I dont have access to this specific device to test but you can do something like this:

from network import Bluetooth
import time

bluetooth = Bluetooth()
bluetooth.start_scan(10)

while True:
    adv = bluetooth.get_adv()
    if adv and binascii.hexlify(adv.mac) == 'XXXXXXXXXX':
        try:
            print('1')
            conn = bluetooth.connect(adv.mac)
        except:
            bluetooth.start_scan(5)
            continue
        break


def characteristic_callback(char):
    v = int.from_bytes(char.value(), "little")
    print("Got new value: {}".format(v))


services = conn.services()
for service in services:
    print("Service: {}".format(service.uuid()))
    if service.uuid() == b'XXXXXXXXXXXXX':
        characteristics = service.characteristics()
        for characteristic in characteristics:
            print("Characteristic: {}".format(characteristic.uuid()))
            if characteristic.uuid() == b'XXXXXXXXXXXX':
                characteristic.callback(trigger=Bluetooth.CHAR_NOTIFY_EVENT,
                                        handler=characteristic_callback,
                                        arg=None)

You will need to replace the XXX parts with values that match your sensor

[luc hanneuse]

Hi @seb ,

Can you help me with the connection and those GATT instructions ?

from network import Bluetooth
import time
bt = Bluetooth()

print("searching")
bt.start_scan(-1)

print("connection")
bt.connect('C47C8D643FAF') # Flower 
print("connected")

I just succeed in a connection.
How can I go further ?

How can I send those 0x0038 , 0xA01F , 0x0033 , 0x0035 and read the returned value ? as describe their : https://wiki.hackerspace.pl/projects:xiaomi-flora

[seb]

@sam_uk said in Reading data from bluetooth device:

gattlib

Our devices do support GATT directly in our firmware, you can find examples of this in the link I provided

[sam_uk]

@seb

Thanks, it seems like paho-mqtt exists in micropython, but not gattlib.

I've found this alternate Esp2866 route so I think I'll pursue that for now.

Thanks

Sam

[seb]

@sam_uk said in Reading data from bluetooth device:

https://wiki.hackerspace.pl/projects:xiaomi-flora

Hi,

The commands you list are for a full installation of python, not micropython, which does not have pip. Please check out our bluetooth api documentation for details about how to use the bluetooth radio in our modules: https://docs.pycom.io/chapter/firmwareapi/pycom/network/bluetooth/