GATTCCharacteristics.write('value') doesn't work!



  • Re: BLE connects but connection is lost immediately

    Hi,

    I notice that with firmware 1.7.6.b1 now the BLE connection function works fine. Now it is possible discover all services and characteristics, but the write function on a characteristic does not work. In my code example chars[0] is a PROP_WRITE charateristic, but when I write something on it, anything happen.

    from network import Bluetooth
    import ubinascii
    import machine
    import uos
    import utime
    
    bt = Bluetooth()
    bt.start_scan(-1)
    while True:
        adv = bt.get_adv()
        try:
            if adv and bt.resolve_adv_data(adv.data, Bluetooth.ADV_NAME_CMPL) == 'X-DOM-NC':
                print(adv.mac)
                conn = bt.connect(adv.mac)
                while not conn.isconnected():
                    machine.idle()
                print("connected")
                print(conn)
                services = conn.services()
                print("services")
                print(services)
                print(services[0].uuid())
                print(services[1].uuid())
                print(services[2].uuid())
                chars = services[2].characteristics()
                print(chars)
                print(chars[0].properties())
                print(chars[1].properties())
                print(chars[0].uuid())
                print(chars[1].uuid())
                chars[0].write(b'x0f')
                utime.sleep(2)
                break
        except:
            print("Error while connecting or reading from the BLE device")
            break
    while True:
        pass
    conn.disconnect()
    

  • administrators

    @kutysam Hmm ok! One of our engineers is having a look at it today so I'll keep you posted!



  • @bucknall
    Hi, I have a ble device and i can confirm that Prop_write_nr works!

    And sorry for piggy backing, cause this issue is related to BLE GATTC too.
    https://forum.pycom.io/topic/1486/reading-descriptors-of-ble-client-gattc-device

    Anyway to change the properties of a gattc manually?

    writeChar.properties() --> 22
    00010110

    00010000 Bluetooth.PROP_NOTIFY
    00000100 Bluetooth.PROP_WRITE_NR
    00000010 Bluetooth.PROP_READ

    I need this to be in.
    00100000 Bluetooth.PROP_INDICATE
    00110110 --> 54

    Android, pygatt and mrsurly fork of micropython has a way to change it as such.


  • administrators

    @Innocenzo Definitely sounds like a bug! I'll check this out later today!



  • @bucknall I notice that if the characteristic that I want write has a property = PROP_WRITE the write function doesn't work. Instead if the characteristic has a property = PROP_WRITE_NR , the function works fine.

    EDIT: I have opened a issue on GitHub


  • administrators

    Hi @Innocenzo,

    Thanks for alerting us to this problem. Would you mind creating an issue on our GitHub repo (https://github.com/pycom/pycom-micropython-sigfox/issues) regarding your concerns?

    Thanks! :)

    Alex


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