BluetoothLE with Arduino UNO R4 WiFi

[s-light]

Hello community,
there is Bluetooth LE support already here 🥳

and i got the Bluetooth Classic working with some simple modules.

now i have a new Arduino UNO R4 WiFi sitting on my Desk -
and i tried to come up with an minimal example to control the onboard LED with DroidPad - and failed..

the App is giving the info on what UUID the U4 has to scann for.
(you can also find it in the code

my sketch is mostly based on these sketches:

• https://github.com/arduino-libraries/ArduinoBLE/blob/master/examples/Central/PeripheralExplorer/PeripheralExplorer.ino
• https://docs.arduino.cc/learn/communication/bluetooth/#control-an-arduino-with-a-smartphone-app

and the examples are all working.

as fare as i have understand - DroidPad is advertising a service with one characteristics.
i can connect and list successfully the characteristics -
but as fare as the scanner sketch tells me - they are all not read write or subcribalbe.
so no way to interact with them..

with the Bluetooth_LE_scann.ino i get this output:

Bluetooth® Low Energy Central - Peripheral Explorer
Found 10:51:5d:49:d0:28 '' 
Found 10:55:44:33:22:27 'NWJ20210709010034�' ffe0
Found 49:41:16:49:28:01 'FP4' 4fbfc1d7-f509-44ab-afe1-62ea40a4b111
Connecting ...
Connected
Discovering attributes ...
Attributes discovered

Device name: FP4
Appearance: 0x0

Service 0 :1801
	Characteristic 2a05, properties 0x20, canSubscribe
		Descriptor 2803, value 0x0205003A2B
		Descriptor 2b3a, value 0x01
	Characteristic 2b3a, properties 0x2, canRead, value 0x01
		Descriptor 2803, value 0x0A0700292B
		Descriptor 2b29, value 0x00
	Characteristic 2b29, properties 0xA, canRead, value 0x00, canWrite
		Descriptor 2803, value 0x0209002A2B
		Descriptor 2b2a, value 0x1A22311CB1EEA982039B84CB0F95A049
	Characteristic 2b2a, properties 0x2, canRead, value 0x1A22311CB1EEA982039B84CB0F95A049
Service 1 :1800
	Characteristic 2a00, properties 0x2, canRead, value 0x465034
		Descriptor 2803, value 0x021800012A
		Descriptor 2a01, value 0x0000
	Characteristic 2a01, properties 0x2, canRead, value 0x0000
		Descriptor 2803, value 0x021A00A62A
		Descriptor 2aa6, value 0x01
	Characteristic 2aa6, properties 0x2, canRead, value 0x01
		Descriptor 2803, value 0x221C00882B
		Descriptor 2b88, value 0x
	Characteristic 2b88, properties 0x22, canRead, canSubscribe
		Descriptor 2902, value 0x
Service 2 :4fbfc1d7-f509-44ab-afe1-62ea40a4b111
	Characteristic dc3f5274-33ba-48de-8246-43bf8985b323, properties 0x10, canSubscribe
		Descriptor 2902, value 0x
Service 3 :4fbfc1d7-f509-44ab-afe1-62ea40a4b111
	Characteristic dc3f5274-33ba-48de-8246-43bf8985b323, properties 0x10, canSubscribe
		Descriptor 2902, value 0x
		Descriptor 2902, value 0x
Service 4 :4fbfc1d7-f509-44ab-afe1-62ea40a4b111
	Characteristic dc3f5274-33ba-48de-8246-43bf8985b323, properties 0x10, canSubscribe
		Descriptor 2902, value 0x
Service 5 :4fbfc1d7-f509-44ab-afe1-62ea40a4b111
	Characteristic dc3f5274-33ba-48de-8246-43bf8985b323, properties 0x10, canSubscribe
		Descriptor 2902, value 0x

Disconnecting ...
Disconnected

with my example i get this output:

00:36:22.101 -> UNO_R4_WiFi-Bluetooth_DroidPad.ino
00:36:22.358 -> Bluethooth Device namens 'HackBLE' fertig initialisiert.
00:36:22.487 -> Gefunden: 'FP4' Service UUID '4fbfc1d7-f509-44ab-afe1-62ea40a4b111'
00:36:22.519 -> Verbinden ...
00:36:22.905 -> Verbunden
00:36:22.905 -> suche Attribute ...
00:36:28.205 -> Attribute gefunden
00:36:28.205 -> DroidPad characteristic nicht lesbar!
00:36:28.205 -> DroidPad characteristic nicht schreibbar!
00:36:28.205 -> DroidPad characteristic abonnierbar..
00:36:33.250 -> subscription failed!

so i thought i have to do a subscription - as it is the only thing the characteristics offer(read is not allowed and write also not..)
but that too fails..

seems i miss something entirely here 🤣

any tips / hints / links to a known working example are welcome :-)

[UmerCodez]

as fare as i have understand - DroidPad is advertising a service with one characteristics.
i can connect and list successfully the characteristics -
but as fare as the scanner sketch tells me - they are all not read write or subcribalbe.
so no way to interact with them..

Thats actually intendend behaviour, I explicitly mentioned in the README section Sending Json Message to DroidPad that:-

You can send JSON messages to DroidPad to update the UI. All connection types are supported except for BLE.

Therefore right now you can't send data to DroidPad with BLE as a connection type. DroidPad only notifies interaction over BLE via notification. Just make sure you writing 0x0001 to the CCCD which is required to enable notification for the characteristic (If the library is not doing this implicitly)

[s-light]

thanks for your reply!
i missed that point in the readme -
and i am fine with this :-)
i just found that - at least - the way i tried - i did not get the notification api to work..

i thought that in the lib it is the characteristic.subscribe() call that enables this..
and that exactly fails:
00:36:33.250 -> subscription failed!
i get the canSubscribe as True - so that part seems to work..
i will ask for this in the arduino forum / BLE library repository as it seems to be partly maybe not an DroidPad thing:

arduino-libraries/ArduinoBLE#71

https://forum.arduino.cc/t/arduinoble-subscribe-fails/1429630
(https://forum.arduino.cc/t/subscribing-to-bluefruit-le-friend-with-arduinoble-not-working/652211/9)

[UmerCodez]

Have you tried connecting your program and subscribing to a custom, notifiable characteristic using the nRF Connect app for testing purpose?