Bluetooth smartwatch

The Lightblue bluetooth app works on my iPhone with the XIAO nrf52840 Sense.
But I need to have the Lightblue properties on a smartwatch. I only need the XIAO to start and stop. Any suggestions?

Hi there and Welcome,
What kind of “properties” ?
With a Xiao Nrf52840 mounted on the Round display, You can connect to other BLE devices (or Xiao’s) monitor inputs and outputs, record data. SO what is it you NEED?
Go For it , what are you trying to achive in this endevor, be specific. The real AI here can help if you explain what your doing.
GL :slight_smile: PJ :christmas_tree:

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i just heard about lightblue the oter day, i was watching a Youtube about MIT App inventor and went thru the process, only to find out that MIT App Inventor BLE does not suppert iphone… I think PC is on the right track, let us know what you are doing with your project and we love to help

Hello PJ,
the property I need is to send a starting signal to a remote Seeed XIAO Sense µC. This µC is the core of my timer (generates pulses between 1 and 2 ms).
The timer is mounted in my controline model airplane, at 20 m distance.
Holding the controline handle in my right hand, I would like to give a start signal to the timer, using my left hand.
Wie an iPhone, using the Lightblue app, it would work, but I cannot handle an iPhone with only my left hand. Simple solution would be a smartwatch, on my right wrist, with an app like Lightblue. But Lightblue is only available for iPhone and iPad.
So my question is, has anybody used a smartwatch to control a bluetooth Seeed? Or is there another option?
Best regards,


Hi there, wnieuwkamp

Seasons Greetings, So If I’m hearing and understanding you correctly then it is possible, You can use a Xiao Nrf52840 BLE on Round touch display to Send a BLE “Start or Stop” command with feedback, to the Remote BLE Device. EASY cake. Do you Know the Service name and Characteristic or descriptor UUID ? It’s like control of an BLE LED On/Off type control or Start/Stop in your scenario.
There are many Examples for doing this but no apps specifically for a smart watch AFAIK.

If your coding chops are up to it, the round display has touch screen and doing the BLE portion is already done for you in Examples if you know the BLE necessary Items above, otherwise post up what you know and I’m certain you can get it done.

Check out the WIKI for the round display to get an idea. You could probably tweak the Hardware test example to do it (i.e. select slider on screen or the switch for the SD card display) to a touch push button “Start/Stop” easily. The connection can be automatic or via SCAN, if there 's more than one. or Connect ,Select(service),send boolean parameter to remote and/or receive confirmation or something along those lines. YMMV :wink: :v:

GL :slight_smile: PJ :christmas_tree:

Sounds like a fun project I would be happy to help with it… currently I am going to have to reformat my whole arduino setup because it takes like literally an hour to open and compile a simple sketch… I
May try to learn platform io

For the time being, I will start with my iPhone strapped to my arm. Then I will dig into programming bluetooth on a smartwatch.
Thanks anyway,

Take a look at this , I believe this is close the code is easy stuff.

GL :-p PJ :santa:

The Arduino software for Bluetooth consists of a setup routine and a void loop (). Sending a value to the Seeed works. But I need that value for following routines to control my timer. How do I get that value ,deeply nested in the loop, available for successive routines? “Goto” or “break” only works within the loop…

you mean like a global variable?

Exactly!! Thanks for your quick reaction.

Changed to global variable (above setup) worked. Thanks. But how do I stop the void loop after the value is found?

you need to structure your program so the void loop always runs… else you stop the running of the entire processor by putting it to sleep…
so for example you want the void loop to check and see what is going on… handle timing and executing sub routines

in the very simplest think of it as a interupt… so the void loop wonders if it needs to do anything… if it does it does… else it does nothing… by doing things i mean executing funtions (sub routines)

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Ah, I was afraid that you could not call external subroutines from the middle of the void loop. Now it works, thanks cgwaltney.