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

[Innocenzo]

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()

[bucknall]

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

[Innocenzo]

@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

[bucknall]

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

[kutysam]

@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.

[bucknall]

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