Android Tutorial Using B4A to develop for a Wear OS 2 watch

I just got a Skagen Falster 2 watch and logged my first experiences of trying to use B4A to develop aps for it. Here's what I did!

First of all setup the watch with the Wear OS app on a phone. Setup carries over the WiFi settings from phone so don’t need to enter a password, the phone watch should connect itself automatically after setup is complete. To develop with B4A you need to become a developer on the watch.
Settings -> System -> About Tap Build Number up to 10 times

Then setup debugging
Settings -> Developer Options

Enable Stay awake while charging and leave on charge while developing to speed up installing apps.
Enable Adb debugging.
Enable Debug over Wifi – might say unavailable – just wait and come back to it, once set it shows the IP address.
Enable Automatically enable WiFi when charging

You can also see the IP address in Setting -> Connectivity -> WiFi and tap on the WiFi access point name which should be showing ‘connected’.

On the PC open a command prompt in SDK platform tools and execute
adb connect <watchIPaddress>

You might get an authentication failure message on the computer and there should be a message on the watch to accept the connection, if you scroll down there should be an ‘always from this computer’ option. Tap it and it should be connected though there won’t be a confirmation on the computer. You need to check that the device is connected whenever you use B4A. Check the connection by executing.
adb devices

If you now start B4A you can work as normal. You don’t need any special manifest entries, a simple program should just work. Most libraries should work, for example I’ve used the GPS library for a simple GPS location finder, and my ScaleImageView library in conjunction with InputListAsync to make a simple image selector and viewer. ScaleImageView works very well on a watch. Instead of pinch zooming employing double tap and drag up or down zooming is more convenient.

You can usually debug a watch app on a phone which is a lot more convenient than on a watch.

In the Designer
Make a layout 390 x 390 scale 2 which is what my watch reports with GetLayoutDeviceValues
Set a suitable Activity title, this will only be seen on the desktop
Check Full Screen and Uncheck Show Title
Comment out AutoscaleAll in the general script

Add the controls but only use Left and Top anchors otherwise on the phone they will stretch across the Activity.

In Main
Add #BridgeLogger: True to attributes

As it is a round watch I draw a circle in Activity_Create after LoadLayout to see how the layout fits.
195 being 390/2, 2 being the Scale on the watch
Dim cv As Canvas
Dim r As Int = 195 * GetDeviceLayoutValues.Scale /2
cv.DrawCircle(r, r, r, Colors.Black, False, 3)

Installation to the device will be slow and if not on the charger with ‘stay awake’ set in developer options it may help to keep the watch awake by circling your fingers on the dial until installation is complete and the downloaded app automatically starts.

Remember that you can send apps from the Play Store on the desktop to the watch as long as the watch is connected to the Internet and you are logged into your account on the Play Store on the desktop. This is easier than typing on the watch.

My watch is displaying a couple of quirks, yours may or may not. Firstly the launcher seems to occasionally forget my sideloaded apps, though Settings -> App Info knows they are there. Reinstalling seems to be the only way to get it back(EDIT: probably my fault for inadvertently reusing pacakge names). Secondly overnight the watch switches WiFi off automatically to save battery, you can tell by the barred cloud icon on the watch face if it has. I haven’t found a way to persuade it reconnect to my router. It should restart when needed but opening the Play Store app doesn’t seem to. A restart may make it reconnect otherwise it needs a factory reset and setup again. (EDIT: It looks like you can manually reconnect by going to Settings -> Connectivity -> WiFi and tap on the network name under the Wi-Fi slider. I'm thought that I had tried this before several times without success but it seems to work now.)
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Dave G

Active Member
Licensed User
Thanks for sharing your experience with Wear OS. I developed an app several months ago and have published it on Play Store and App Store. It's call Winch Calc and in addition to Wear OS I also have a version for regular Android and iOS using B4X. The Wear OS version accounts for the small screen. Wasn't ever able to debug or release directly to the watch for watchface, so I use ADB install to move it to the watch. Wear OS was a challenge, but worth the effort.

I also tried my hand at a watchface. Caters to old eyes. I have a TicWatch E2 that I only use for development as I don't wear a watch.
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Well-Known Member
Licensed User
Longtime User
Interesting, thanks for sharing. I tried to write an app on an older Wear device and it was a nightmare to develop for as you had to develop a companion app and back then the devices didnt have their own network connection (communication was via the phone).

Based on you experience I'll have to have another go at it on my newer watch as I never bothered looking into it again.

Dave G

Active Member
Licensed User
I developed my Wear OS app without a companion phone/tablet app. It doesn't connect to network, but I'm guessing it would be able to.

BTW, I do my development using USB connection and it works great because my TicWatch has as USB connection/charger.


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Longtime User
I'm real happy to report that I've been able to build a basic B4A app and get it installed to my new TicWatch E3.
It just arrived this afternoon, and I was able to get it setup and the app installed in about 2 hours.
All with @agraham 's help here.

I've attached the app to this message.

Thank you sir.
Mark Stuart


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Next thing I want to do is create a phone app that will transfer data from the phone app to the watch, and send back data to the phone.